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+<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
+ "http://www.w3.org/TR/html40/loose.dtd">
+<HTML>
+<!-- Created on January, 10 2005 by texi2html 1.66 -->
+<!--
+Written by: Lionel Cons <Lionel.Cons@cern.ch> (original author)
+ Karl Berry <karl@freefriends.org>
+ Olaf Bachmann <obachman@mathematik.uni-kl.de>
+ and many others.
+Maintained by: Many creative people <dev@texi2html.cvshome.org>
+Send bugs and suggestions to <users@texi2html.cvshome.org>
+
+-->
+<HEAD>
+<TITLE>SLIB: Other Packages</TITLE>
+
+<META NAME="description" CONTENT="SLIB: Other Packages">
+<META NAME="keywords" CONTENT="SLIB: Other Packages">
+<META NAME="resource-type" CONTENT="document">
+<META NAME="distribution" CONTENT="global">
+<META NAME="Generator" CONTENT="texi2html 1.66">
+
+</HEAD>
+
+<BODY LANG="en" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#800080" ALINK="#FF0000">
+
+<A NAME="SEC183"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_6.html#SEC182"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_6.html#SEC140"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H1> 7. Other Packages </H1>
+<!--docid::SEC183::-->
+<P>
+
+<TABLE BORDER="0" CELLSPACING="0">
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC184">7.1 Data Structures</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Various data structures.</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC207">7.2 Sorting and Searching</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC225">7.3 Procedures</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Miscellaneous utility procedures.</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC235">7.4 Standards Support</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Support for Scheme Standards.</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC263">7.5 Session Support</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">REPL and Debugging.</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC269">7.6 System Interface</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'system, 'getenv, and other programs.</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC276">7.7 Extra-SLIB Packages</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Outside the envelope.</TD></TR>
+</TABLE>
+<P>
+
+<A NAME="Data Structures"></A>
+<HR SIZE="6">
+<A NAME="SEC184"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC185"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H2> 7.1 Data Structures </H2>
+<!--docid::SEC184::-->
+<P>
+
+<TABLE BORDER="0" CELLSPACING="0">
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC185">7.1.1 Arrays</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'array</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC186">7.1.2 Subarrays</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'subarray</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC187">7.1.3 Array Mapping</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'array-for-each</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC188">7.1.4 Association Lists</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'alist</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC189">7.1.5 Byte</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'byte</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC190">7.1.6 Byte/Number Conversions</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'byte-number</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC192">7.1.7 MAT-File Format</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'matfile</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC193">7.1.8 Portable Image Files</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'pnm</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC194">7.1.9 Collections</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'collect</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC195">7.1.10 Dynamic Data Type</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'dynamic</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC196">7.1.11 Hash Tables</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'hash-table</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC197">7.1.12 Macroless Object System</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'object</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC204">7.1.16 Priority Queues</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'priority-queue</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC205">7.1.17 Queues</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'queue</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC206">7.1.18 Records</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'record</TD></TR>
+</TABLE>
+<P>
+
+<A NAME="Arrays"></A>
+<HR SIZE="6">
+<A NAME="SEC185"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC186"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.1.1 Arrays </H3>
+<!--docid::SEC185::-->
+<P>
+
+<CODE>(require 'array)</CODE>
+<A NAME="IDX1094"></A>
+</P>
+<P>
+
+<A NAME="IDX1095"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>array?</B> <I>obj</I>
+<DD><P>
+
+Returns <CODE>#t</CODE> if the <VAR>obj</VAR> is an array, and <CODE>#f</CODE> if not.
+</P>
+</DL>
+<EM>Note:</EM> Arrays are not disjoint from other Scheme types. Strings
+and vectors also satisfy <CODE>array?</CODE>. A disjoint array predicate can
+be written:
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define (strict-array? obj)
+ (and (array? obj) (not (string? obj)) (not (vector? obj))))
+</pre></td></tr></table><P>
+
+<A NAME="IDX1096"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>array=?</B> <I>array1 array2</I>
+<DD><P>
+
+Returns <CODE>#t</CODE> if <VAR>array1</VAR> and <VAR>array2</VAR> have the same rank and shape and the
+corresponding elements of <VAR>array1</VAR> and <VAR>array2</VAR> are <CODE>equal?</CODE>.
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(array=? (create-array '#(foo) 3 3)
+ (create-array '#(foo) '(0 2) '(0 2)))
+ => #t
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1097"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>create-array</B> <I>prototype bound1 bound2 <small>...</small></I>
+<DD><P>
+
+Creates and returns an array of type <VAR>prototype</VAR> with dimensions <VAR>bound1</VAR>, <VAR>bound2</VAR>,
+<small>...</small> and filled with elements from <VAR>prototype</VAR>. <VAR>prototype</VAR> must be an array,
+vector, or string. The implementation-dependent type of the returned
+array will be the same as the type of <VAR>prototype</VAR>; except if that would be a
+vector or string with non-zero origin, in which case some variety of
+array will be returned.
+</P>
+<P>
+
+If the <VAR>prototype</VAR> has no elements, then the initial contents of the returned
+array are unspecified. Otherwise, the returned array will be filled
+with the element at the origin of <VAR>prototype</VAR>.
+</P>
+</DL>
+These functions return a prototypical uniform-array enclosing the
+optional argument (which must be of the correct type). If the
+uniform-array type is supported by the implementation, then it is
+returned; defaulting to the next larger precision type; resorting
+finally to vector.
+<P>
+
+<A NAME="IDX1098"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>ac64</B> <I>z</I>
+<DD><P>
+
+<A NAME="IDX1099"></A>
+<DT><U>Function:</U> <B>ac64</B>
+<DD>Returns a high-precision complex uniform-array prototype.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1100"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>ac32</B> <I>z</I>
+<DD><P>
+
+<A NAME="IDX1101"></A>
+<DT><U>Function:</U> <B>ac32</B>
+<DD>Returns a complex uniform-array prototype.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1102"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>ar64</B> <I>x</I>
+<DD><P>
+
+<A NAME="IDX1103"></A>
+<DT><U>Function:</U> <B>ar64</B>
+<DD>Returns a high-precision real uniform-array prototype.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1104"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>ar32</B> <I>x</I>
+<DD><P>
+
+<A NAME="IDX1105"></A>
+<DT><U>Function:</U> <B>ar32</B>
+<DD>Returns a real uniform-array prototype.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1106"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>as64</B> <I>n</I>
+<DD><P>
+
+<A NAME="IDX1107"></A>
+<DT><U>Function:</U> <B>as64</B>
+<DD>Returns an exact signed integer uniform-array prototype with at least
+64 bits of precision.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1108"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>as32</B> <I>n</I>
+<DD><P>
+
+<A NAME="IDX1109"></A>
+<DT><U>Function:</U> <B>as32</B>
+<DD>Returns an exact signed integer uniform-array prototype with at least
+32 bits of precision.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1110"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>as16</B> <I>n</I>
+<DD><P>
+
+<A NAME="IDX1111"></A>
+<DT><U>Function:</U> <B>as16</B>
+<DD>Returns an exact signed integer uniform-array prototype with at least
+16 bits of precision.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1112"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>as8</B> <I>n</I>
+<DD><P>
+
+<A NAME="IDX1113"></A>
+<DT><U>Function:</U> <B>as8</B>
+<DD>Returns an exact signed integer uniform-array prototype with at least
+8 bits of precision.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1114"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>au64</B> <I>k</I>
+<DD><P>
+
+<A NAME="IDX1115"></A>
+<DT><U>Function:</U> <B>au64</B>
+<DD>Returns an exact non-negative integer uniform-array prototype with at
+least 64 bits of precision.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1116"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>au32</B> <I>k</I>
+<DD><P>
+
+<A NAME="IDX1117"></A>
+<DT><U>Function:</U> <B>au32</B>
+<DD>Returns an exact non-negative integer uniform-array prototype with at
+least 32 bits of precision.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1118"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>au16</B> <I>k</I>
+<DD><P>
+
+<A NAME="IDX1119"></A>
+<DT><U>Function:</U> <B>au16</B>
+<DD>Returns an exact non-negative integer uniform-array prototype with at
+least 16 bits of precision.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1120"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>au8</B> <I>k</I>
+<DD><P>
+
+<A NAME="IDX1121"></A>
+<DT><U>Function:</U> <B>au8</B>
+<DD>Returns an exact non-negative integer uniform-array prototype with at
+least 8 bits of precision.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1122"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>at1</B> <I>bool</I>
+<DD><P>
+
+<A NAME="IDX1123"></A>
+<DT><U>Function:</U> <B>at1</B>
+<DD>Returns a boolean uniform-array prototype.
+</P>
+</DL>
+When constructing an array, <VAR>bound</VAR> is either an inclusive range of
+indices expressed as a two element list, or an upper bound expressed as
+a single integer. So
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(create-array '#(foo) 3 3) == (create-array '#(foo) '(0 2) '(0 2))
+</pre></td></tr></table><P>
+
+<A NAME="IDX1124"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>make-shared-array</B> <I>array mapper bound1 bound2 <small>...</small></I>
+<DD><P>
+
+<CODE>make-shared-array</CODE> can be used to create shared subarrays of other
+arrays. The <VAR>mapper</VAR> is a function that translates coordinates in
+the new array into coordinates in the old array. A <VAR>mapper</VAR> must be
+linear, and its range must stay within the bounds of the old array, but
+it can be otherwise arbitrary. A simple example:
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define fred (create-array '#(#f) 8 8))
+(define freds-diagonal
+ (make-shared-array fred (lambda (i) (list i i)) 8))
+(array-set! freds-diagonal 'foo 3)
+(array-ref fred 3 3)
+ => FOO
+(define freds-center
+ (make-shared-array fred (lambda (i j) (list (+ 3 i) (+ 3 j)))
+ 2 2))
+(array-ref freds-center 0 0)
+ => FOO
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1125"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>array-rank</B> <I>obj</I>
+<DD><P>
+
+Returns the number of dimensions of <VAR>obj</VAR>. If <VAR>obj</VAR> is not an array, 0 is
+returned.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1126"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>array-shape</B> <I>array</I>
+<DD><P>
+
+Returns a list of inclusive bounds.
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(array-shape (create-array '#() 3 5))
+ => ((0 2) (0 4))
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1127"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>array-dimensions</B> <I>array</I>
+<DD><P>
+
+<CODE>array-dimensions</CODE> is similar to <CODE>array-shape</CODE> but replaces
+elements with a 0 minimum with one greater than the maximum.
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(array-dimensions (create-array '#() 3 5))
+ => (3 5)
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1128"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>array-in-bounds?</B> <I>array index1 index2 <small>...</small></I>
+<DD><P>
+
+Returns <CODE>#t</CODE> if its arguments would be acceptable to
+<CODE>array-ref</CODE>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1129"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>array-ref</B> <I>array index1 index2 <small>...</small></I>
+<DD><P>
+
+Returns the (<VAR>index1</VAR>, <VAR>index2</VAR>, <small>...</small>) element of <VAR>array</VAR>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1130"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>array-set!</B> <I>array obj index1 index2 <small>...</small></I>
+<DD><P>
+
+Stores <VAR>obj</VAR> in the (<VAR>index1</VAR>, <VAR>index2</VAR>, <small>...</small>) element of <VAR>array</VAR>. The value returned
+by <CODE>array-set!</CODE> is unspecified.
+</P>
+</DL>
+<P>
+
+<A NAME="Subarrays"></A>
+<HR SIZE="6">
+<A NAME="SEC186"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC185"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC187"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.1.2 Subarrays </H3>
+<!--docid::SEC186::-->
+<P>
+
+<CODE>(require 'subarray)</CODE>
+<A NAME="IDX1131"></A>
+</P>
+<P>
+
+<A NAME="IDX1132"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>subarray</B> <I>array select <small>...</small></I>
+<DD><P>
+
+selects a subset of an array. For <VAR>array</VAR> of rank n, there must be at least
+n <VAR>selects</VAR> arguments. For 0 &lt;= <I>j</I> &lt; n, <VAR>selects</VAR><I>j</I> is either an integer, a
+list of two integers within the range for the <I>j</I>th index, or #f.
+</P>
+<P>
+
+When <VAR>selects</VAR><I>j</I> is a list of two integers, then the <I>j</I>th index is
+restricted to that subrange in the returned array.
+</P>
+<P>
+
+When <VAR>selects</VAR><I>j</I> is #f, then the full range of the <I>j</I>th index is
+accessible in the returned array. An elided argument is equivalent to #f.
+</P>
+<P>
+
+When <VAR>selects</VAR><I>j</I> is an integer, then the rank of the returned array is
+less than <VAR>array</VAR>, and only elements whose <I>j</I>th index equals <VAR>selects</VAR><I>j</I> are
+shared.
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>&gt; (define ra '#2A((a b c) (d e f)))
+#&lt;unspecified&gt;
+&gt; (subarray ra 0 #f)
+#1A(a b c)
+&gt; (subarray ra 1 #f)
+#1A(d e f)
+&gt; (subarray ra #f 1)
+#1A(b e)
+&gt; (subarray ra '(0 1) #f)
+#2A((a b c) (d e f))
+&gt; (subarray ra #f '(0 1))
+#2A((a b) (d e))
+&gt; (subarray ra #f '(1 2))
+#2A((b c) (e f))
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1133"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>subarray0</B> <I>array select <small>...</small></I>
+<DD><P>
+
+Behaves like subarray, but aligns the returned array origin to
+0 <small>...</small>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1134"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>array-align</B> <I>array coord <small>...</small></I>
+<DD><P>
+
+Returns an array shared with <VAR>array</VAR> but with a different origin. The <VAR>coords</VAR>
+are the exact integer coordinates of the new origin. Indexes
+corresponding to missing or #f coordinates are not realigned.
+</P>
+<P>
+
+For example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define ra2 (create-array '#(5) '(5 9) '(-4 0)))
+(array-shape ra2) => ((5 9) (-4 0))
+(array-shape (array-align ra2 0 0)) => ((0 4) (0 4))
+(array-shape (array-align ra2 0)) => ((0 4) (-4 0))
+(array-shape (array-align ra2)) => ((5 9) (-4 0))
+(array-shape (array-align ra2 0 #f)) => ((0 4) (-4 0))
+(array-shape (array-align ra2 #f 0)) => ((5 9) (0 4))
+</pre></td></tr></table></DL>
+
+<A NAME="IDX1135"></A>
+<DL>
+<DT><U>Function:</U> <B>array-trim</B> <I>array trim <small>...</small></I>
+<DD><P>
+
+Returns a subarray sharing contents with <VAR>array</VAR> except for slices removed
+from either side of each dimension. Each of the <VAR>trims</VAR> is an exact
+integer indicating how much to trim. A positive <VAR>s</VAR> trims the
+data from the lower end and reduces the upper bound of the result; a
+negative <VAR>s</VAR> trims from the upper end and increases the lower
+bound.
+</P>
+<P>
+
+For example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(array-trim '#(0 1 2 3 4) 1) => #1A(1 2 3 4) ;; shape is ((0 3))
+(array-trim '#(0 1 2 3 4) -1) => #1A(0 1 2 3) ;; shape is ((1 4))
+
+(require 'array-for-each)
+(define (centered-difference ra)
+ (array-map - (array-trim ra 1) (array-trim ra -1)))
+(define (forward-difference ra)
+ (array-map - (array-trim ra 1) ra))
+(define (backward-difference ra)
+ (array-map - ra (array-trim ra -1)))
+
+(centered-difference '#(0 1 3 5 9 22))
+ => #1A(3 4 6 17) ;;shape is ((1 4))
+(backward-difference '#(0 1 3 5 9 22))
+ => #1A(1 2 2 4 13) ;; shape is ((1 5))
+(forward-difference '#(0 1 3 5 9 22))
+ => #(1 2 2 4 13) ;; shape is ((0 4))
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="Array Mapping"></A>
+<HR SIZE="6">
+<A NAME="SEC187"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC186"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC188"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.1.3 Array Mapping </H3>
+<!--docid::SEC187::-->
+<P>
+
+<CODE>(require 'array-for-each)</CODE>
+<A NAME="IDX1136"></A>
+</P>
+<P>
+
+<A NAME="IDX1137"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>array-map!</B> <I>array0 proc array1 <small>...</small></I>
+<DD><P>
+
+<VAR>array1</VAR>, <small>...</small> must have the same number of dimensions as
+<VAR>array0</VAR> and have a range for each index which includes the range
+for the corresponding index in <VAR>array0</VAR>. <VAR>proc</VAR> is applied to
+each tuple of elements of <VAR>array1</VAR> <small>...</small> and the result is stored
+as the corresponding element in <VAR>array0</VAR>. The value returned is
+unspecified. The order of application is unspecified.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1138"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>array-map</B> <I>prototype proc array1 array2 <small>...</small></I>
+<DD><P>
+
+<VAR>array2</VAR>, <small>...</small> must have the same number of dimensions as
+<VAR>array1</VAR> and have a range for each index which includes the
+range for the corresponding index in <VAR>array1</VAR>. <VAR>proc</VAR> is
+applied to each tuple of elements of <VAR>array1</VAR>, <VAR>array2</VAR>,
+<small>...</small> and the result is stored as the corresponding element in a
+new array of type <VAR>prototype</VAR>. The new array is returned. The
+order of application is unspecified.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1139"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>array-for-each</B> <I>proc array0 <small>...</small></I>
+<DD><P>
+
+<VAR>proc</VAR> is applied to each tuple of elements of <VAR>array0</VAR> <small>...</small>
+in row-major order. The value returned is unspecified.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1140"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>array-indexes</B> <I>array</I>
+<DD><P>
+
+Returns an array of lists of indexes for <VAR>array</VAR> such that, if
+<VAR>li</VAR> is a list of indexes for which <VAR>array</VAR> is defined,
+(equal? <VAR>li</VAR> (apply array-ref (array-indexes <VAR>array</VAR>)
+<VAR>li</VAR>)).
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1141"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>array-index-map!</B> <I>array proc</I>
+<DD><P>
+
+applies <VAR>proc</VAR> to the indices of each element of <VAR>array</VAR> in
+turn, storing the result in the corresponding element. The value
+returned and the order of application are unspecified.
+</P>
+<P>
+
+One can implement <VAR>array-indexes</VAR> as
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define (array-indexes array)
+ (let ((ra (apply create-array '#() (array-shape array))))
+ (array-index-map! ra (lambda x x))
+ ra))
+</pre></td></tr></table>Another example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define (apl:index-generator n)
+ (let ((v (make-vector n 1)))
+ (array-index-map! v (lambda (i) i))
+ v))
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1142"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>array-copy!</B> <I>source destination</I>
+<DD><P>
+
+Copies every element from vector or array <VAR>source</VAR> to the
+corresponding element of <VAR>destination</VAR>. <VAR>destination</VAR> must
+have the same rank as <VAR>source</VAR>, and be at least as large in each
+dimension. The order of copying is unspecified.
+</P>
+</DL>
+<P>
+
+<A NAME="Association Lists"></A>
+<HR SIZE="6">
+<A NAME="SEC188"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC187"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC189"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.1.4 Association Lists </H3>
+<!--docid::SEC188::-->
+<P>
+
+<CODE>(require 'alist)</CODE>
+<A NAME="IDX1143"></A>
+</P>
+<P>
+
+Alist functions provide utilities for treating a list of key-value pairs
+as an associative database. These functions take an equality predicate,
+<VAR>pred</VAR>, as an argument. This predicate should be repeatable,
+symmetric, and transitive.
+</P>
+<P>
+
+Alist functions can be used with a secondary index method such as hash
+tables for improved performance.
+</P>
+<P>
+
+<A NAME="IDX1144"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>predicate-&gt;asso</B> <I>pred</I>
+<DD><P>
+
+Returns an <EM>association function</EM> (like <CODE>assq</CODE>, <CODE>assv</CODE>, or
+<A NAME="IDX1145"></A>
+<CODE>assoc</CODE>) corresponding to <VAR>pred</VAR>. The returned function
+returns a key-value pair whose key is <CODE>pred</CODE>-equal to its first
+argument or <CODE>#f</CODE> if no key in the alist is <VAR>pred</VAR>-equal to the
+first argument.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1146"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>alist-inquirer</B> <I>pred</I>
+<DD><P>
+
+Returns a procedure of 2 arguments, <VAR>alist</VAR> and <VAR>key</VAR>, which
+returns the value associated with <VAR>key</VAR> in <VAR>alist</VAR> or <CODE>#f</CODE> if
+<VAR>key</VAR> does not appear in <VAR>alist</VAR>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1147"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>alist-associator</B> <I>pred</I>
+<DD><P>
+
+Returns a procedure of 3 arguments, <VAR>alist</VAR>, <VAR>key</VAR>, and
+<VAR>value</VAR>, which returns an alist with <VAR>key</VAR> and <VAR>value</VAR>
+associated. Any previous value associated with <VAR>key</VAR> will be
+lost. This returned procedure may or may not have side effects on its
+<VAR>alist</VAR> argument. An example of correct usage is:
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define put (alist-associator string-ci=?))
+(define alist '())
+(set! alist (put alist &quot;Foo&quot; 9))
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1148"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>alist-remover</B> <I>pred</I>
+<DD><P>
+
+Returns a procedure of 2 arguments, <VAR>alist</VAR> and <VAR>key</VAR>, which
+returns an alist with an association whose <VAR>key</VAR> is key removed.
+This returned procedure may or may not have side effects on its
+<VAR>alist</VAR> argument. An example of correct usage is:
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define rem (alist-remover string-ci=?))
+(set! alist (rem alist &quot;foo&quot;))
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1149"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>alist-map</B> <I>proc alist</I>
+<DD><P>
+
+Returns a new association list formed by mapping <VAR>proc</VAR> over the
+keys and values of <VAR>alist</VAR>. <VAR>proc</VAR> must be a function of 2
+arguments which returns the new value part.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1150"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>alist-for-each</B> <I>proc alist</I>
+<DD><P>
+
+Applies <VAR>proc</VAR> to each pair of keys and values of <VAR>alist</VAR>.
+<VAR>proc</VAR> must be a function of 2 arguments. The returned value is
+unspecified.
+</P>
+</DL>
+<P>
+
+<A NAME="Byte"></A>
+<HR SIZE="6">
+<A NAME="SEC189"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC188"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC190"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.1.5 Byte </H3>
+<!--docid::SEC189::-->
+<P>
+
+<CODE>(require 'byte)</CODE>
+<A NAME="IDX1151"></A>
+</P>
+<P>
+
+Some algorithms are expressed in terms of arrays of small integers.
+Using Scheme strings to implement these arrays is not portable vis-a-vis
+the correspondence between integers and characters and non-ascii
+character sets. These functions abstract the notion of a <EM>byte</EM>.
+<A NAME="IDX1152"></A>
+<A NAME="IDX1153"></A>
+</P>
+<P>
+
+<A NAME="IDX1154"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>byte-ref</B> <I>bytes k</I>
+<DD><P>
+
+<VAR>k</VAR> must be a valid index of <VAR>bytes</VAR>. <CODE>byte-ref</CODE> returns byte <VAR>k</VAR> of <VAR>bytes</VAR> using
+zero-origin indexing.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1155"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>byte-set!</B> <I>bytes k byte</I>
+<DD><P>
+
+<VAR>k</VAR> must be a valid index of <VAR>bytes</VAR>, and <VAR>byte</VAR> must be a small
+nonnegative integer. <CODE>byte-set!</CODE> stores <VAR>byte</VAR> in element <VAR>k</VAR> of <VAR>bytes</VAR> and
+returns an unspecified value.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1156"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>make-bytes</B> <I>k byte</I>
+<DD><P>
+
+<A NAME="IDX1157"></A>
+<DT><U>Function:</U> <B>make-bytes</B> <I>k</I>
+<DD><CODE>make-bytes</CODE> returns a newly allocated byte-array of length <VAR>k</VAR>. If <VAR>byte</VAR> is
+given, then all elements of the byte-array are initialized to <VAR>byte</VAR>,
+otherwise the contents of the byte-array are unspecified.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1158"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>bytes-length</B> <I>bytes</I>
+<DD><P>
+
+<CODE>bytes-length</CODE> returns length of byte-array <VAR>bytes</VAR>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1159"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>bytes</B> <I>byte <small>...</small></I>
+<DD><P>
+
+Returns a newly allocated byte-array composed of the small
+nonnegative arguments.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1160"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>bytes-&gt;list</B> <I>bytes</I>
+<DD><P>
+
+<CODE>bytes-&gt;list</CODE> returns a newly allocated list of the bytes that make up the
+given byte-array.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1161"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>list-&gt;bytes</B> <I>bytes</I>
+<DD><P>
+
+<CODE>list-&gt;bytes</CODE> returns a newly allocated byte-array formed from the small
+nonnegative integers in the list <VAR>bytes</VAR>.
+</P>
+</DL>
+<CODE>Bytes-&gt;list</CODE> and <CODE>list-&gt;bytes</CODE> are inverses so far as
+<CODE>equal?</CODE> is concerned.
+<A NAME="IDX1162"></A>
+<P>
+
+<A NAME="IDX1163"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>bytes-copy</B> <I>bytes</I>
+<DD><P>
+
+Returns a newly allocated copy of the given <VAR>bytes</VAR>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1164"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>bytes-reverse!</B> <I>bytes</I>
+<DD><P>
+
+Reverses the order of byte-array <VAR>bytes</VAR>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1165"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>bytes-reverse</B> <I>bytes</I>
+<DD><P>
+
+Returns a newly allocated bytes-array consisting of the elements of
+<VAR>bytes</VAR> in reverse order.
+</P>
+</DL>
+<A NAME="IDX1166"></A>
+Input and output of bytes should be with ports opened in <EM>binary</EM>
+<A NAME="IDX1167"></A>
+mode (see section <A HREF="slib_2.html#SEC16">2.3 Input/Output</A>). Calling <CODE>open-file</CODE> with 'rb or
+<A NAME="IDX1168"></A>
+'wb modes argument will return a binary port if the Scheme
+implementation supports it.
+<P>
+
+<A NAME="IDX1169"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>write-byte</B> <I>byte port</I>
+<DD><P>
+
+<A NAME="IDX1170"></A>
+<DT><U>Function:</U> <B>write-byte</B> <I>byte</I>
+<DD>Writes the byte <VAR>byte</VAR> (not an external representation of the byte) to
+the given <VAR>port</VAR> and returns an unspecified value. The <VAR>port</VAR> argument may
+be omitted, in which case it defaults to the value returned by
+<CODE>current-output-port</CODE>.
+<A NAME="IDX1171"></A>
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1172"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>read-byte</B> <I>port</I>
+<DD><P>
+
+<A NAME="IDX1173"></A>
+<DT><U>Function:</U> <B>read-byte</B>
+<DD>Returns the next byte available from the input <VAR>port</VAR>, updating the <VAR>port</VAR>
+to point to the following byte. If no more bytes are available, an
+end-of-file object is returned. <VAR>port</VAR> may be omitted, in which case it
+defaults to the value returned by <CODE>current-input-port</CODE>.
+<A NAME="IDX1174"></A>
+</P>
+</DL>
+When reading and writing binary numbers with <CODE>read-bytes</CODE> and
+<CODE>write-bytes</CODE>, the sign of the length argument determines the
+endianness (order) of bytes. Positive treats them as big-endian,
+the first byte input or output is highest order. Negative treats
+them as little-endian, the first byte input or output is the lowest
+order.
+<P>
+
+Once read in, SLIB treats byte sequences as big-endian. The
+multi-byte sequences produced and used by number conversion routines
+see section <A HREF="slib_7.html#SEC190">7.1.6 Byte/Number Conversions</A> are always big-endian.
+</P>
+<P>
+
+<A NAME="IDX1175"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>read-bytes</B> <I>n port</I>
+<DD><P>
+
+<A NAME="IDX1176"></A>
+<DT><U>Function:</U> <B>read-bytes</B> <I>n</I>
+<DD><CODE>read-bytes</CODE> returns a newly allocated bytes-array filled with
+<CODE>(abs <VAR>n</VAR>)</CODE> bytes read from <VAR>port</VAR>. If <VAR>n</VAR> is positive, then
+the first byte read is stored at index 0; otherwise the last byte
+read is stored at index 0. Note that the length of the returned
+string will be less than <CODE>(abs <VAR>n</VAR>)</CODE> if <VAR>port</VAR> reaches
+end-of-file.
+</P>
+<P>
+
+<VAR>port</VAR> may be omitted, in which case it defaults to the value returned
+by <CODE>current-input-port</CODE>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1177"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>write-bytes</B> <I>bytes n port</I>
+<DD><P>
+
+<A NAME="IDX1178"></A>
+<DT><U>Function:</U> <B>write-bytes</B> <I>bytes n</I>
+<DD><CODE>write-bytes</CODE> writes <CODE>(abs <VAR>n</VAR>)</CODE> bytes to output-port <VAR>port</VAR>. If <VAR>n</VAR> is
+positive, then the first byte written is index 0 of <VAR>bytes</VAR>; otherwise
+the last byte written is index 0 of <VAR>bytes</VAR>. <CODE>write-bytes</CODE> returns an unspecified
+value.
+</P>
+<P>
+
+<VAR>port</VAR> may be omitted, in which case it defaults to the value returned
+by <CODE>current-output-port</CODE>.
+</P>
+</DL>
+<CODE>substring-read!</CODE> and <CODE>substring-write</CODE> provide
+lower-level procedures for reading and writing blocks of bytes. The
+relative size of <VAR>start</VAR> and <VAR>end</VAR> determines the order of
+writing.
+<P>
+
+<A NAME="IDX1179"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>substring-read!</B> <I>string start end port</I>
+<DD><P>
+
+<A NAME="IDX1180"></A>
+<DT><U>Procedure:</U> <B>substring-read!</B> <I>string start end</I>
+<DD>Fills <VAR>string</VAR> with up to <CODE>(abs (- <VAR>start</VAR> <VAR>end</VAR>))</CODE> bytes
+read from <VAR>port</VAR>. The first byte read is stored at index <VAR>string</VAR>.
+<CODE>substring-read!</CODE> returns the number of bytes read.
+</P>
+<P>
+
+<VAR>port</VAR> may be omitted, in which case it defaults to the value returned
+by <CODE>current-input-port</CODE>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1181"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>substring-write</B> <I>string start end port</I>
+<DD><P>
+
+<A NAME="IDX1182"></A>
+<DT><U>Function:</U> <B>substring-write</B> <I>string start end</I>
+<DD><CODE>substring-write</CODE> writes <CODE>(abs (- <VAR>start</VAR> <VAR>end</VAR>))</CODE> bytes to
+output-port <VAR>port</VAR>. The first byte written is index <VAR>start</VAR> of <VAR>string</VAR>. <CODE>substring-write</CODE>
+returns the number of bytes written.
+</P>
+<P>
+
+<VAR>port</VAR> may be omitted, in which case it defaults to the value returned
+by <CODE>current-output-port</CODE>.
+</P>
+</DL>
+<P>
+
+<A NAME="Byte/Number Conversions"></A>
+<HR SIZE="6">
+<A NAME="SEC190"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC189"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC192"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.1.6 Byte/Number Conversions </H3>
+<!--docid::SEC190::-->
+<P>
+
+<CODE>(require 'byte-number)</CODE>
+<A NAME="IDX1183"></A>
+</P>
+<P>
+
+The multi-byte sequences produced and used by numeric conversion
+routines are always big-endian. Endianness can be changed during
+reading and writing bytes using <CODE>read-bytes</CODE> and
+<CODE>write-bytes</CODE> See section <A HREF="slib_7.html#SEC189">read-bytes</A>.
+</P>
+<P>
+
+The sign of the length argument to bytes/integer conversion
+procedures determines the signedness of the number.
+</P>
+<P>
+
+<A NAME="IDX1184"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>bytes-&gt;integer</B> <I>bytes n</I>
+<DD><P>
+
+Converts the first <CODE>(abs <VAR>n</VAR>)</CODE> bytes of big-endian <VAR>bytes</VAR> array
+to an integer. If <VAR>n</VAR> is negative then the integer coded by the
+bytes are treated as two's-complement (can be negative).
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(bytes-&gt;integer (bytes 0 0 0 15) -4) => 15
+(bytes-&gt;integer (bytes 0 0 0 15) 4) => 15
+(bytes-&gt;integer (bytes 255 255 255 255) -4) => -1
+(bytes-&gt;integer (bytes 255 255 255 255) 4) => 4294967295
+(bytes-&gt;integer (bytes 128 0 0 0) -4) => -2147483648
+(bytes-&gt;integer (bytes 128 0 0 0) 4) => 2147483648
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1185"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>integer-&gt;bytes</B> <I>n len</I>
+<DD><P>
+
+Converts the integer <VAR>n</VAR> to a byte-array of <CODE>(abs <VAR>n</VAR>)</CODE>
+bytes. If <VAR>n</VAR> and <VAR>len</VAR> are both negative, then the bytes in the
+returned array are coded two's-complement.
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(bytes-&gt;list (integer-&gt;bytes 15 -4)) => (0 0 0 15)
+(bytes-&gt;list (integer-&gt;bytes 15 4)) => (0 0 0 15)
+(bytes-&gt;list (integer-&gt;bytes -1 -4)) => (255 255 255 255)
+(bytes-&gt;list (integer-&gt;bytes 4294967295 4)) => (255 255 255 255)
+(bytes-&gt;list (integer-&gt;bytes -2147483648 -4)) => (128 0 0 0)
+(bytes-&gt;list (integer-&gt;bytes 2147483648 4)) => (128 0 0 0)
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1186"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>bytes-&gt;ieee-float</B> <I>bytes</I>
+<DD><P>
+
+<VAR>bytes</VAR> must be a 4-element byte-array. <CODE>bytes-&gt;ieee-float</CODE> calculates and returns the
+value of <VAR>bytes</VAR> interpreted as a big-endian IEEE 4-byte (32-bit) number.
+</P>
+</DL>
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(bytes-&gt;ieee-float (bytes #x40 0 0 0)) => 2.0
+(bytes-&gt;ieee-float (bytes #x40 #xd0 0 0)) => 6.5
+(bytes-&gt;ieee-float (bytes #xc0 #xd0 0 0)) => -6.5
+
+(bytes-&gt;ieee-float (bytes 0 #x80 0 0)) => 11.754943508222875e-39
+(bytes-&gt;ieee-float (bytes 0 #x40 0 0)) => 5.877471754111437e-39
+(bytes-&gt;ieee-float (bytes 0 0 0 1)) => 1.401298464324817e-45
+
+(bytes-&gt;ieee-float (bytes #xff #x80 0 0)) => -1/0
+(bytes-&gt;ieee-float (bytes #x7f #x80 0 0)) => 1/0
+(bytes-&gt;ieee-float (bytes #x7f #x80 0 1)) => 0/0
+</pre></td></tr></table><P>
+
+<A NAME="IDX1187"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>bytes-&gt;ieee-double</B> <I>bytes</I>
+<DD><P>
+
+<VAR>bytes</VAR> must be a 8-element byte-array. <CODE>bytes-&gt;ieee-double</CODE> calculates and returns the
+value of <VAR>bytes</VAR> interpreted as a big-endian IEEE 8-byte (64-bit) number.
+</P>
+</DL>
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(bytes-&gt;ieee-double (bytes 0 0 0 0 0 0 0 0)) => 0.0
+(bytes-&gt;ieee-double (bytes #x40 0 0 0 0 0 0 0)) => 2
+(bytes-&gt;ieee-double (bytes #x40 #x1A 0 0 0 0 0 0)) => 6.5
+(bytes-&gt;ieee-double (bytes #xC0 #x1A 0 0 0 0 0 0)) => -6.5
+
+(bytes-&gt;ieee-double (bytes 0 8 0 0 0 0 0 0)) => 11.125369292536006e-309
+(bytes-&gt;ieee-double (bytes 0 4 0 0 0 0 0 0)) => 5.562684646268003e-309
+(bytes-&gt;ieee-double (bytes 0 0 0 0 0 0 0 1)) => 4.0e-324
+
+(bytes-&gt;ieee-double (bytes #xFF #xF0 0 0 0 0 0 0)) => -1/0
+(bytes-&gt;ieee-double (bytes #x7F #xF0 0 0 0 0 0 0)) => 1/0
+(bytes-&gt;ieee-double (bytes #x7F #xF8 0 0 0 0 0 0)) => 0/0
+</pre></td></tr></table><P>
+
+<A NAME="IDX1188"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>ieee-float-&gt;bytes</B> <I>x</I>
+<DD><P>
+
+Returns a 4-element byte-array encoding the IEEE single-precision
+floating-point of <VAR>x</VAR>.
+</P>
+</DL>
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(bytes-&gt;list (ieee-float-&gt;bytes 2.0)) => (64 0 0 0)
+(bytes-&gt;list (ieee-float-&gt;bytes 6.5)) => (64 208 0 0)
+(bytes-&gt;list (ieee-float-&gt;bytes -6.5)) => (192 208 0 0)
+
+(bytes-&gt;list (ieee-float-&gt;bytes 11.754943508222875e-39)) => ( 0 128 0 0)
+(bytes-&gt;list (ieee-float-&gt;bytes 5.877471754111438e-39)) => ( 0 64 0 0)
+(bytes-&gt;list (ieee-float-&gt;bytes 1.401298464324817e-45)) => ( 0 0 0 1)
+
+(bytes-&gt;list (ieee-float-&gt;bytes -1/0)) => (255 128 0 0)
+(bytes-&gt;list (ieee-float-&gt;bytes 1/0)) => (127 128 0 0)
+(bytes-&gt;list (ieee-float-&gt;bytes 0/0)) => (127 128 0 1)
+</pre></td></tr></table><P>
+
+<A NAME="IDX1189"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>ieee-double-&gt;bytes</B> <I>x</I>
+<DD><P>
+
+Returns a 8-element byte-array encoding the IEEE double-precision
+floating-point of <VAR>x</VAR>.
+</P>
+</DL>
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(bytes-&gt;list (ieee-double-&gt;bytes 2.0)) => (64 0 0 0 0 0 0 0)
+(bytes-&gt;list (ieee-double-&gt;bytes 6.5)) => (64 26 0 0 0 0 0 0)
+(bytes-&gt;list (ieee-double-&gt;bytes -6.5)) => (192 26 0 0 0 0 0 0)
+
+(bytes-&gt;list (ieee-double-&gt;bytes 11.125369292536006e-309))
+ => ( 0 8 0 0 0 0 0 0)
+(bytes-&gt;list (ieee-double-&gt;bytes 5.562684646268003e-309))
+ => ( 0 4 0 0 0 0 0 0)
+(bytes-&gt;list (ieee-double-&gt;bytes 4.0e-324))
+ => ( 0 0 0 0 0 0 0 1)
+
+(bytes-&gt;list (ieee-double-&gt;bytes -1/0)) => (255 240 0 0 0 0 0 0)
+(bytes-&gt;list (ieee-double-&gt;bytes 1/0)) => (127 240 0 0 0 0 0 0)
+(bytes-&gt;list (ieee-double-&gt;bytes 0/0)) => (127 248 0 0 0 0 0 0)
+</pre></td></tr></table><P>
+
+<A NAME="SEC191"></A>
+<H4> Byte Collation Order </H4>
+<!--docid::SEC191::-->
+<P>
+
+The <CODE>string&lt;?</CODE> ordering of big-endian byte-array
+representations of fixed and IEEE floating-point numbers agrees with
+the numerical ordering only when those numbers are non-negative.
+</P>
+<P>
+
+Straighforward modification of these formats can extend the
+byte-collating order to work for their entire ranges. This
+agreement enables the full range of numbers as keys in
+<EM>indexed-sequential-access-method</EM> databases.
+<A NAME="IDX1190"></A>
+</P>
+<P>
+
+<A NAME="IDX1191"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>integer-byte-collate!</B> <I>byte-vector</I>
+<DD><P>
+
+Modifies sign bit of <VAR>byte-vector</VAR> so that <CODE>string&lt;?</CODE> ordering of
+two's-complement byte-vectors matches numerical order. <CODE>integer-byte-collate!</CODE> returns
+<VAR>byte-vector</VAR> and is its own functional inverse.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1192"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>integer-byte-collate</B> <I>byte-vector</I>
+<DD><P>
+
+Returns copy of <VAR>byte-vector</VAR> with sign bit modified so that <CODE>string&lt;?</CODE>
+ordering of two's-complement byte-vectors matches numerical order.
+<CODE>integer-byte-collate</CODE> is its own functional inverse.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1193"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>ieee-byte-collate!</B> <I>byte-vector</I>
+<DD><P>
+
+Modifies <VAR>byte-vector</VAR> so that <CODE>string&lt;?</CODE> ordering of IEEE floating-point
+byte-vectors matches numerical order. <CODE>ieee-byte-collate!</CODE> returns <VAR>byte-vector</VAR>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1194"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>ieee-byte-decollate!</B> <I>byte-vector</I>
+<DD><P>
+
+Given <VAR>byte-vector</VAR> modified by <CODE>IEEE-byte-collate!</CODE>, reverses the <VAR>byte-vector</VAR>
+modifications.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1195"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>ieee-byte-collate</B> <I>byte-vector</I>
+<DD><P>
+
+Returns copy of <VAR>byte-vector</VAR> encoded so that <CODE>string&lt;?</CODE> ordering of IEEE
+floating-point byte-vectors matches numerical order.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1196"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>ieee-byte-decollate</B> <I>byte-vector</I>
+<DD><P>
+
+Given <VAR>byte-vector</VAR> returned by <CODE>IEEE-byte-collate</CODE>, reverses the <VAR>byte-vector</VAR>
+modifications.
+</P>
+</DL>
+<P>
+
+<A NAME="MAT-File Format"></A>
+<HR SIZE="6">
+<A NAME="SEC192"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC190"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC193"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.1.7 MAT-File Format </H3>
+<!--docid::SEC192::-->
+<P>
+
+<CODE>(require 'matfile)</CODE>
+<A NAME="IDX1197"></A>
+<A NAME="IDX1198"></A>
+</P>
+<P>
+
+<A HREF="http://www.mathworks.com/access/helpdesk/help/pdf_doc/matlab/matfile_format.pdf">http://www.mathworks.com/access/helpdesk/help/pdf_doc/matlab/matfile_format.pdf</A>
+</P>
+<P>
+
+This package reads MAT-File Format version 4 (MATLAB) binary data
+files. MAT-files written from big-endian or little-endian computers
+having IEEE format numbers are currently supported. Support for files
+written from VAX or Cray machines could also be added.
+</P>
+<P>
+
+The numeric and text matrix types handled; support for <EM>sparse</EM>
+<A NAME="IDX1199"></A>
+matrices awaits a sample file.
+</P>
+<P>
+
+<A NAME="IDX1200"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>matfile:read</B> <I>filename</I>
+<DD><VAR>filename</VAR> should be a string naming an existing file containing a
+MATLAB Version 4 MAT-File. The <CODE>matfile:read</CODE> procedure reads matrices from the
+file and returns a list of the results; a list of the name string and
+array for each matrix.
+</DL>
+<P>
+
+<A NAME="IDX1201"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>matfile:load</B> <I>filename</I>
+<DD><VAR>filename</VAR> should be a string naming an existing file containing a
+MATLAB Version 4 MAT-File. The <CODE>matfile:load</CODE> procedure reads matrices from the
+file and defines the <CODE>string-ci-&gt;symbol</CODE> for each matrix to its
+corresponding array. <CODE>matfile:load</CODE> returns a list of the symbols defined.
+</DL>
+<P>
+
+<A NAME="Portable Image Files"></A>
+<HR SIZE="6">
+<A NAME="SEC193"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC192"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC194"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.1.8 Portable Image Files </H3>
+<!--docid::SEC193::-->
+<P>
+
+<CODE>(require 'pnm)</CODE>
+<A NAME="IDX1202"></A>
+</P>
+<P>
+
+<A NAME="IDX1203"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>pnm:type-dimensions</B> <I>path</I>
+<DD><P>
+
+The string <VAR>path</VAR> must name a <EM>portable bitmap graphics</EM> file.
+<A NAME="IDX1204"></A>
+<CODE>pnm:type-dimensions</CODE> returns a list of 4 items:
+<OL>
+<LI>
+A symbol describing the type of the file named by <VAR>path</VAR>.
+<LI>
+The image width in pixels.
+<LI>
+The image height in pixels.
+<LI>
+The maximum value of pixels assume in the file.
+</OL>
+<P>
+
+The current set of file-type symbols is:
+</P>
+<DL COMPACT>
+<DT>pbm
+<DD><DT>pbm-raw
+<DD><A NAME="IDX1205"></A>
+<A NAME="IDX1206"></A>
+Black-and-White image; pixel values are 0 or 1.
+<DT>pgm
+<DD><DT>pgm-raw
+<DD><A NAME="IDX1207"></A>
+<A NAME="IDX1208"></A>
+Gray (monochrome) image; pixel values are from 0 to <VAR>maxval</VAR>
+specified in file header.
+<DT>ppm
+<DD><DT>ppm-raw
+<DD><A NAME="IDX1209"></A>
+<A NAME="IDX1210"></A>
+RGB (full color) image; red, green, and blue interleaved pixel values
+are from 0 to <VAR>maxval</VAR>
+</DL>
+</DL>
+<P>
+
+<A NAME="IDX1211"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>pnm:image-file-&gt;array</B> <I>path array</I>
+<DD><P>
+
+Reads the <EM>portable bitmap graphics</EM> file named by <VAR>path</VAR> into
+<A NAME="IDX1212"></A>
+<VAR>array</VAR>. <VAR>array</VAR> must be the correct size and type for
+<VAR>path</VAR>. <VAR>array</VAR> is returned.
+</P>
+<P>
+
+<A NAME="IDX1213"></A>
+<DT><U>Function:</U> <B>pnm:image-file-&gt;array</B> <I>path</I>
+<DD></P>
+<P>
+
+<CODE>pnm:image-file-&gt;array</CODE> creates and returns an array with the
+<EM>portable bitmap graphics</EM> file named by <VAR>path</VAR> read into it.
+<A NAME="IDX1214"></A>
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1215"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>pnm:array-write</B> <I>type array maxval path comment <small>...</small></I>
+<DD><P>
+
+Writes the contents of <VAR>array</VAR> to a <VAR>type</VAR> image file named <VAR>path</VAR>. The file
+will have pixel values between 0 and <VAR>maxval</VAR>, which must be compatible
+with <VAR>type</VAR>. For `<SAMP>pbm</SAMP>' files, <VAR>maxval</VAR> must be `<SAMP>1</SAMP>'.
+<VAR>comment</VAR>s are included in the file header.
+</P>
+</DL>
+<P>
+
+<A NAME="Collections"></A>
+<HR SIZE="6">
+<A NAME="SEC194"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC193"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC195"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.1.9 Collections </H3>
+<!--docid::SEC194::-->
+<P>
+
+<CODE>(require 'collect)</CODE>
+<A NAME="IDX1216"></A>
+</P>
+<P>
+
+Routines for managing collections. Collections are aggregate data
+structures supporting iteration over their elements, similar to the
+Dylan(TM) language, but with a different interface. They have
+<EM>elements</EM> indexed by corresponding <EM>keys</EM>, although the keys
+may be implicit (as with lists).
+</P>
+<P>
+
+New types of collections may be defined as YASOS objects (see section <A HREF="slib_3.html#SEC40">3.8 Yasos</A>).
+They must support the following operations:
+</P>
+<P>
+
+<UL>
+<LI>
+<CODE>(collection? <VAR>self</VAR>)</CODE> (always returns <CODE>#t</CODE>);
+<P>
+
+</P>
+<LI>
+<CODE>(size <VAR>self</VAR>)</CODE> returns the number of elements in the collection;
+<P>
+
+</P>
+<LI>
+<CODE>(print <VAR>self</VAR> <VAR>port</VAR>)</CODE> is a specialized print operation
+for the collection which prints a suitable representation on the given
+<VAR>port</VAR> or returns it as a string if <VAR>port</VAR> is <CODE>#t</CODE>;
+<P>
+
+</P>
+<LI>
+<A NAME="IDX1217"></A>
+<CODE>(gen-elts <VAR>self</VAR>)</CODE> returns a thunk which on successive
+invocations yields elements of <VAR>self</VAR> in order or gives an error if
+it is invoked more than <CODE>(size <VAR>self</VAR>)</CODE> times;
+<P>
+
+</P>
+<LI>
+<A NAME="IDX1218"></A>
+<CODE>(gen-keys <VAR>self</VAR>)</CODE> is like <CODE>gen-elts</CODE>, but yields the
+collection's keys in order.
+</UL>
+<P>
+
+They might support specialized <CODE>for-each-key</CODE> and
+<CODE>for-each-elt</CODE> operations.
+</P>
+<P>
+
+<A NAME="IDX1219"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>collection?</B> <I>obj</I>
+<DD>A predicate, true initially of lists, vectors and strings. New sorts of
+collections must answer <CODE>#t</CODE> to <CODE>collection?</CODE>.
+</DL>
+<P>
+
+<A NAME="IDX1220"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>map-elts</B> <I>proc collection1 <small>...</small></I>
+<DD><A NAME="IDX1221"></A>
+<DT><U>Procedure:</U> <B>do-elts</B> <I>proc collection1 <small>...</small></I>
+<DD><VAR>proc</VAR> is a procedure taking as many arguments as there are
+<VAR>collections</VAR> (at least one). The <VAR>collections</VAR> are iterated
+over in their natural order and <VAR>proc</VAR> is applied to the elements
+yielded by each iteration in turn. The order in which the arguments are
+supplied corresponds to te order in which the <VAR>collections</VAR> appear.
+<CODE>do-elts</CODE> is used when only side-effects of <VAR>proc</VAR> are of
+interest and its return value is unspecified. <CODE>map-elts</CODE> returns a
+collection (actually a vector) of the results of the applications of
+<VAR>proc</VAR>.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(map-elts + (list 1 2 3) (vector 1 2 3))
+ => #(2 4 6)
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1222"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>map-keys</B> <I>proc collection1 <small>...</small></I>
+<DD><A NAME="IDX1223"></A>
+<DT><U>Procedure:</U> <B>do-keys</B> <I>proc collection1 <small>...</small></I>
+<DD>These are analogous to <CODE>map-elts</CODE> and <CODE>do-elts</CODE>, but each
+iteration is over the <VAR>collections</VAR>' <EM>keys</EM> rather than their
+elements.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(map-keys + (list 1 2 3) (vector 1 2 3))
+ => #(0 2 4)
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1224"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>for-each-key</B> <I>collection proc</I>
+<DD><A NAME="IDX1225"></A>
+<DT><U>Procedure:</U> <B>for-each-elt</B> <I>collection proc</I>
+<DD>These are like <CODE>do-keys</CODE> and <CODE>do-elts</CODE> but only for a single
+collection; they are potentially more efficient.
+</DL>
+<P>
+
+<A NAME="IDX1226"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>reduce</B> <I>proc seed collection1 <small>...</small></I>
+<DD>A generalization of the list-based <CODE>reduce-init</CODE>
+(see section <A HREF="slib_7.html#SEC211">7.2.1.3 Lists as sequences</A>) to collections which will shadow the
+list-based version if <CODE>(require 'collect)</CODE> follows
+<A NAME="IDX1227"></A>
+<CODE>(require 'common-list-functions)</CODE> (see section <A HREF="slib_7.html#SEC208">7.2.1 Common List Functions</A>).
+<A NAME="IDX1228"></A>
+<P>
+
+Examples:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(reduce + 0 (vector 1 2 3))
+ => 6
+(reduce union '() '((a b c) (b c d) (d a)))
+ => (c b d a).
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1229"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>any?</B> <I>pred collection1 <small>...</small></I>
+<DD>A generalization of the list-based <CODE>some</CODE> (see section <A HREF="slib_7.html#SEC211">7.2.1.3 Lists as sequences</A>) to collections.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(any? odd? (list 2 3 4 5))
+ => #t
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1230"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>every?</B> <I>pred collection1 <small>...</small></I>
+<DD>A generalization of the list-based <CODE>every</CODE>
+(see section <A HREF="slib_7.html#SEC211">7.2.1.3 Lists as sequences</A>) to collections.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(every? collection? '((1 2) #(1 2)))
+ => #t
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1231"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>empty?</B> <I>collection</I>
+<DD>Returns <CODE>#t</CODE> iff there are no elements in <VAR>collection</VAR>.
+<P>
+
+<CODE>(empty? <VAR>collection</VAR>) == (zero? (size <VAR>collection</VAR>))</CODE>
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1232"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>size</B> <I>collection</I>
+<DD>Returns the number of elements in <VAR>collection</VAR>.
+</DL>
+<P>
+
+<A NAME="IDX1233"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>Setter</B> <I>list-ref</I>
+<DD>See <A HREF="slib_3.html#SEC43">3.8.3 Setters</A> for a definition of <EM>setter</EM>. N.B.
+<CODE>(setter list-ref)</CODE> doesn't work properly for element 0 of a
+list.
+</DL>
+<P>
+
+Here is a sample collection: <CODE>simple-table</CODE> which is also a
+<CODE>table</CODE>.
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define-predicate TABLE?)
+(define-operation (LOOKUP table key failure-object))
+(define-operation (ASSOCIATE! table key value)) ;; returns key
+(define-operation (REMOVE! table key)) ;; returns value
+
+(define (MAKE-SIMPLE-TABLE)
+ (let ( (table (list)) )
+ (object
+ ;; table behaviors
+ ((TABLE? self) #t)
+ ((SIZE self) (size table))
+ ((PRINT self port) (format port &quot;#&lt;SIMPLE-TABLE&gt;&quot;))
+ ((LOOKUP self key failure-object)
+ (cond
+ ((assq key table) =&gt; cdr)
+ (else failure-object)
+ ))
+ ((ASSOCIATE! self key value)
+ (cond
+ ((assq key table)
+ =&gt; (lambda (bucket) (set-cdr! bucket value) key))
+ (else
+ (set! table (cons (cons key value) table))
+ key)
+ ))
+ ((REMOVE! self key);; returns old value
+ (cond
+ ((null? table) (slib:error &quot;TABLE:REMOVE! Key not found: &quot; key))
+ ((eq? key (caar table))
+ (let ( (value (cdar table)) )
+ (set! table (cdr table))
+ value)
+ )
+ (else
+ (let loop ( (last table) (this (cdr table)) )
+ (cond
+ ((null? this)
+ (slib:error &quot;TABLE:REMOVE! Key not found: &quot; key))
+ ((eq? key (caar this))
+ (let ( (value (cdar this)) )
+ (set-cdr! last (cdr this))
+ value)
+ )
+ (else
+ (loop (cdr last) (cdr this)))
+ ) ) )
+ ))
+ ;; collection behaviors
+ ((COLLECTION? self) #t)
+ ((GEN-KEYS self) (collect:list-gen-elts (map car table)))
+ ((GEN-ELTS self) (collect:list-gen-elts (map cdr table)))
+ ((FOR-EACH-KEY self proc)
+ (for-each (lambda (bucket) (proc (car bucket))) table)
+ )
+ ((FOR-EACH-ELT self proc)
+ (for-each (lambda (bucket) (proc (cdr bucket))) table)
+ ) ) ) )
+</pre></td></tr></table><P>
+
+<A NAME="Dynamic Data Type"></A>
+<HR SIZE="6">
+<A NAME="SEC195"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC194"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC196"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.1.10 Dynamic Data Type </H3>
+<!--docid::SEC195::-->
+<P>
+
+<CODE>(require 'dynamic)</CODE>
+<A NAME="IDX1234"></A>
+</P>
+<P>
+
+<A NAME="IDX1235"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>make-dynamic</B> <I>obj</I>
+<DD>Create and returns a new <EM>dynamic</EM> whose global value is <VAR>obj</VAR>.
+</DL>
+<P>
+
+<A NAME="IDX1236"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>dynamic?</B> <I>obj</I>
+<DD>Returns true if and only if <VAR>obj</VAR> is a dynamic. No object
+satisfying <CODE>dynamic?</CODE> satisfies any of the other standard type
+predicates.
+</DL>
+<P>
+
+<A NAME="IDX1237"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>dynamic-ref</B> <I>dyn</I>
+<DD>Return the value of the given dynamic in the current dynamic
+environment.
+</DL>
+<P>
+
+<A NAME="IDX1238"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>dynamic-set!</B> <I>dyn obj</I>
+<DD>Change the value of the given dynamic to <VAR>obj</VAR> in the current
+dynamic environment. The returned value is unspecified.
+</DL>
+<P>
+
+<A NAME="IDX1239"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>call-with-dynamic-binding</B> <I>dyn obj thunk</I>
+<DD>Invoke and return the value of the given thunk in a new, nested dynamic
+environment in which the given dynamic has been bound to a new location
+whose initial contents are the value <VAR>obj</VAR>. This dynamic
+environment has precisely the same extent as the invocation of the thunk
+and is thus captured by continuations created within that invocation and
+re-established by those continuations when they are invoked.
+</DL>
+<P>
+
+The <CODE>dynamic-bind</CODE> macro is not implemented.
+</P>
+<P>
+
+<A NAME="Hash Tables"></A>
+<HR SIZE="6">
+<A NAME="SEC196"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC195"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC197"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.1.11 Hash Tables </H3>
+<!--docid::SEC196::-->
+<P>
+
+<CODE>(require 'hash-table)</CODE>
+<A NAME="IDX1240"></A>
+</P>
+<P>
+
+<A NAME="IDX1241"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>predicate-&gt;hash</B> <I>pred</I>
+<DD><P>
+
+Returns a hash function (like <CODE>hashq</CODE>, <CODE>hashv</CODE>, or
+<CODE>hash</CODE>) corresponding to the equality predicate <VAR>pred</VAR>.
+<VAR>pred</VAR> should be <CODE>eq?</CODE>, <CODE>eqv?</CODE>, <CODE>equal?</CODE>, <CODE>=</CODE>,
+<CODE>char=?</CODE>, <CODE>char-ci=?</CODE>, <CODE>string=?</CODE>, or
+<CODE>string-ci=?</CODE>.
+</P>
+</DL>
+A hash table is a vector of association lists.
+<P>
+
+<A NAME="IDX1242"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>make-hash-table</B> <I>k</I>
+<DD><P>
+
+Returns a vector of <VAR>k</VAR> empty (association) lists.
+</P>
+</DL>
+Hash table functions provide utilities for an associative database.
+These functions take an equality predicate, <VAR>pred</VAR>, as an argument.
+<VAR>pred</VAR> should be <CODE>eq?</CODE>, <CODE>eqv?</CODE>, <CODE>equal?</CODE>, <CODE>=</CODE>,
+<CODE>char=?</CODE>, <CODE>char-ci=?</CODE>, <CODE>string=?</CODE>, or
+<CODE>string-ci=?</CODE>.
+<P>
+
+<A NAME="IDX1243"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>predicate-&gt;hash-asso</B> <I>pred</I>
+<DD><P>
+
+Returns a hash association function of 2 arguments, <VAR>key</VAR> and
+<VAR>hashtab</VAR>, corresponding to <VAR>pred</VAR>. The returned function
+returns a key-value pair whose key is <VAR>pred</VAR>-equal to its first
+argument or <CODE>#f</CODE> if no key in <VAR>hashtab</VAR> is <VAR>pred</VAR>-equal to
+the first argument.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1244"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>hash-inquirer</B> <I>pred</I>
+<DD><P>
+
+Returns a procedure of 2 arguments, <VAR>hashtab</VAR> and <VAR>key</VAR>, which
+returns the value associated with <VAR>key</VAR> in <VAR>hashtab</VAR> or
+<CODE>#f</CODE> if <VAR>key</VAR> does not appear in <VAR>hashtab</VAR>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1245"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>hash-associator</B> <I>pred</I>
+<DD><P>
+
+Returns a procedure of 3 arguments, <VAR>hashtab</VAR>, <VAR>key</VAR>, and
+<VAR>value</VAR>, which modifies <VAR>hashtab</VAR> so that <VAR>key</VAR> and
+<VAR>value</VAR> associated. Any previous value associated with <VAR>key</VAR>
+will be lost.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1246"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>hash-remover</B> <I>pred</I>
+<DD><P>
+
+Returns a procedure of 2 arguments, <VAR>hashtab</VAR> and <VAR>key</VAR>, which
+modifies <VAR>hashtab</VAR> so that the association whose key is <VAR>key</VAR> is
+removed.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1247"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>hash-map</B> <I>proc hash-table</I>
+<DD><P>
+
+Returns a new hash table formed by mapping <VAR>proc</VAR> over the
+keys and values of <VAR>hash-table</VAR>. <VAR>proc</VAR> must be a function of 2
+arguments which returns the new value part.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1248"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>hash-for-each</B> <I>proc hash-table</I>
+<DD><P>
+
+Applies <VAR>proc</VAR> to each pair of keys and values of <VAR>hash-table</VAR>.
+<VAR>proc</VAR> must be a function of 2 arguments. The returned value is
+unspecified.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1249"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>hash-rehasher</B> <I>pred</I>
+<DD><P>
+
+<CODE>hash-rehasher</CODE> accepts a hash table predicate and returns a function of two
+arguments <VAR>hashtab</VAR> and <VAR>new-k</VAR> which is specialized for
+that predicate.
+</P>
+<P>
+
+This function is used for nondestrutively resizing a hash table.
+<VAR>hashtab</VAR> should be an existing hash-table using <VAR>pred</VAR>, <VAR>new-k</VAR>
+is the size of a new hash table to be returned. The new hash table
+will have all of the associations of the old hash table.
+</P>
+</DL>
+<P>
+
+<A NAME="Object"></A>
+<HR SIZE="6">
+<A NAME="SEC197"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC196"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC198"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.1.12 Macroless Object System </H3>
+<!--docid::SEC197::-->
+<P>
+
+<CODE>(require 'object)</CODE>
+<A NAME="IDX1250"></A>
+</P>
+<P>
+
+This is the Macroless Object System written by Wade Humeniuk
+(whumeniu@datap.ca). Conceptual Tributes: <A HREF="slib_3.html#SEC40">3.8 Yasos</A>, MacScheme's
+%object, CLOS, Lack of R4RS macros.
+</P>
+<P>
+
+<HR SIZE="6">
+<A NAME="SEC198"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC197"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC199"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.1.13 Concepts </H3>
+<!--docid::SEC198::-->
+<DL COMPACT>
+
+<DT>OBJECT
+<DD>An object is an ordered association-list (by <CODE>eq?</CODE>) of methods
+(procedures). Methods can be added (<CODE>make-method!</CODE>), deleted
+(<CODE>unmake-method!</CODE>) and retrieved (<CODE>get-method</CODE>). Objects may
+inherit methods from other objects. The object binds to the environment
+it was created in, allowing closures to be used to hide private
+procedures and data.
+<P>
+
+</P>
+<DT>GENERIC-METHOD
+<DD>A generic-method associates (in terms of <CODE>eq?</CODE>) object's method.
+This allows scheme function style to be used for objects. The calling
+scheme for using a generic method is <CODE>(generic-method object param1
+param2 ...)</CODE>.
+<P>
+
+</P>
+<DT>METHOD
+<DD>A method is a procedure that exists in the object. To use a method
+get-method must be called to look-up the method. Generic methods
+implement the get-method functionality. Methods may be added to an
+object associated with any scheme obj in terms of eq?
+<P>
+
+</P>
+<DT>GENERIC-PREDICATE
+<DD>A generic method that returns a boolean value for any scheme obj.
+<P>
+
+</P>
+<DT>PREDICATE
+<DD>A object's method asscociated with a generic-predicate. Returns
+<CODE>#t</CODE>.
+</DL>
+<P>
+
+<HR SIZE="6">
+<A NAME="SEC199"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC198"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC200"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.1.14 Procedures </H3>
+<!--docid::SEC199::-->
+<P>
+
+<A NAME="IDX1251"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>make-object</B> <I>ancestor <small>...</small></I>
+<DD>Returns an object. Current object implementation is a tagged vector.
+<VAR>ancestor</VAR>s are optional and must be objects in terms of object?.
+<VAR>ancestor</VAR>s methods are included in the object. Multiple
+<VAR>ancestor</VAR>s might associate the same generic-method with a method.
+In this case the method of the <VAR>ancestor</VAR> first appearing in the
+list is the one returned by <CODE>get-method</CODE>.
+</DL>
+<P>
+
+<A NAME="IDX1252"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>object?</B> <I>obj</I>
+<DD>Returns boolean value whether <VAR>obj</VAR> was created by make-object.
+</DL>
+<P>
+
+<A NAME="IDX1253"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>make-generic-method</B> <I>exception-procedure</I>
+<DD>Returns a procedure which be associated with an object's methods. If
+<VAR>exception-procedure</VAR> is specified then it is used to process
+non-objects.
+</DL>
+<P>
+
+<A NAME="IDX1254"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>make-generic-predicate</B>
+<DD>Returns a boolean procedure for any scheme object.
+</DL>
+<P>
+
+<A NAME="IDX1255"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>make-method!</B> <I>object generic-method method</I>
+<DD>Associates <VAR>method</VAR> to the <VAR>generic-method</VAR> in the object. The
+<VAR>method</VAR> overrides any previous association with the
+<VAR>generic-method</VAR> within the object. Using <CODE>unmake-method!</CODE>
+will restore the object's previous association with the
+<VAR>generic-method</VAR>. <VAR>method</VAR> must be a procedure.
+</DL>
+<P>
+
+<A NAME="IDX1256"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>make-predicate!</B> <I>object generic-preciate</I>
+<DD>Makes a predicate method associated with the <VAR>generic-predicate</VAR>.
+</DL>
+<P>
+
+<A NAME="IDX1257"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>unmake-method!</B> <I>object generic-method</I>
+<DD>Removes an object's association with a <VAR>generic-method</VAR> .
+</DL>
+<P>
+
+<A NAME="IDX1258"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>get-method</B> <I>object generic-method</I>
+<DD>Returns the object's method associated (if any) with the
+<VAR>generic-method</VAR>. If no associated method exists an error is
+flagged.
+</DL>
+<P>
+
+<HR SIZE="6">
+<A NAME="SEC200"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC199"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC201"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.1.15 Examples </H3>
+<!--docid::SEC200::-->
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(require 'object)
+<A NAME="IDX1259"></A>
+(define instantiate (make-generic-method))
+
+(define (make-instance-object . ancestors)
+ (define self (apply make-object
+ (map (lambda (obj) (instantiate obj)) ancestors)))
+ (make-method! self instantiate (lambda (self) self))
+ self)
+
+(define who (make-generic-method))
+(define imigrate! (make-generic-method))
+(define emigrate! (make-generic-method))
+(define describe (make-generic-method))
+(define name (make-generic-method))
+(define address (make-generic-method))
+(define members (make-generic-method))
+
+(define society
+ (let ()
+ (define self (make-instance-object))
+ (define population '())
+ (make-method! self imigrate!
+ (lambda (new-person)
+ (if (not (eq? new-person self))
+ (set! population (cons new-person population)))))
+ (make-method! self emigrate!
+ (lambda (person)
+ (if (not (eq? person self))
+ (set! population
+ (comlist:remove-if (lambda (member)
+ (eq? member person))
+ population)))))
+ (make-method! self describe
+ (lambda (self)
+ (map (lambda (person) (describe person)) population)))
+ (make-method! self who
+ (lambda (self) (map (lambda (person) (name person))
+ population)))
+ (make-method! self members (lambda (self) population))
+ self))
+
+(define (make-person %name %address)
+ (define self (make-instance-object society))
+ (make-method! self name (lambda (self) %name))
+ (make-method! self address (lambda (self) %address))
+ (make-method! self who (lambda (self) (name self)))
+ (make-method! self instantiate
+ (lambda (self)
+ (make-person (string-append (name self) &quot;-son-of&quot;)
+ %address)))
+ (make-method! self describe
+ (lambda (self) (list (name self) (address self))))
+ (imigrate! self)
+ self)
+</pre></td></tr></table><P>
+
+<HR SIZE="6">
+<A NAME="SEC201"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC200"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC202"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H4> 7.1.15.1 Inverter Documentation </H4>
+<!--docid::SEC201::-->
+Inheritance:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre> &lt;inverter&gt;::(&lt;number&gt; &lt;description&gt;)
+</pre></td></tr></table>Generic-methods
+<TABLE><tr><td>&nbsp;</td><td class=example><pre> &lt;inverter&gt;::value => &lt;number&gt;::value
+ &lt;inverter&gt;::set-value! => &lt;number&gt;::set-value!
+ &lt;inverter&gt;::describe => &lt;description&gt;::describe
+ &lt;inverter&gt;::help
+ &lt;inverter&gt;::invert
+ &lt;inverter&gt;::inverter?
+</pre></td></tr></table><P>
+
+<HR SIZE="6">
+<A NAME="SEC202"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC201"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC203"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H4> 7.1.15.2 Number Documention </H4>
+<!--docid::SEC202::-->
+Inheritance
+<TABLE><tr><td>&nbsp;</td><td class=example><pre> &lt;number&gt;::()
+</pre></td></tr></table>Slots
+<TABLE><tr><td>&nbsp;</td><td class=example><pre> &lt;number&gt;::&lt;x&gt;
+</pre></td></tr></table>Generic Methods
+<TABLE><tr><td>&nbsp;</td><td class=example><pre> &lt;number&gt;::value
+ &lt;number&gt;::set-value!
+</pre></td></tr></table><P>
+
+<HR SIZE="6">
+<A NAME="SEC203"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC202"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC204"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H4> 7.1.15.3 Inverter code </H4>
+<!--docid::SEC203::-->
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(require 'object)
+<A NAME="IDX1260"></A>
+(define value (make-generic-method (lambda (val) val)))
+(define set-value! (make-generic-method))
+(define invert (make-generic-method
+ (lambda (val)
+ (if (number? val)
+ (/ 1 val)
+ (error &quot;Method not supported:&quot; val)))))
+(define noop (make-generic-method))
+(define inverter? (make-generic-predicate))
+(define describe (make-generic-method))
+(define help (make-generic-method))
+
+(define (make-number x)
+ (define self (make-object))
+ (make-method! self value (lambda (this) x))
+ (make-method! self set-value!
+ (lambda (this new-value) (set! x new-value)))
+ self)
+
+(define (make-description str)
+ (define self (make-object))
+ (make-method! self describe (lambda (this) str))
+ (make-method! self help (lambda (this) &quot;Help not available&quot;))
+ self)
+
+(define (make-inverter)
+ (let* ((self (make-object
+ (make-number 1)
+ (make-description &quot;A number which can be inverted&quot;)))
+ (&lt;value&gt; (get-method self value)))
+ (make-method! self invert (lambda (self) (/ 1 (&lt;value&gt; self))))
+ (make-predicate! self inverter?)
+ (unmake-method! self help)
+ (make-method! self help
+ (lambda (self)
+ (display &quot;Inverter Methods:&quot;) (newline)
+ (display &quot; (value inverter) ==&gt; n&quot;) (newline)))
+ self))
+
+;;;; Try it out
+
+(define invert! (make-generic-method))
+
+(define x (make-inverter))
+
+(make-method! x invert! (lambda (x) (set-value! x (/ 1 (value x)))))
+
+(value x) => 1
+(set-value! x 33) => undefined
+(invert! x) => undefined
+(value x) => 1/33
+
+(unmake-method! x invert!) => undefined
+
+(invert! x) error--> ERROR: Method not supported: x
+</pre></td></tr></table><P>
+
+<A NAME="Priority Queues"></A>
+<HR SIZE="6">
+<A NAME="SEC204"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC203"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC205"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.1.16 Priority Queues </H3>
+<!--docid::SEC204::-->
+<P>
+
+<CODE>(require 'priority-queue)</CODE>
+<A NAME="IDX1261"></A>
+</P>
+<P>
+
+This algorithm for priority queues is due to
+<CITE>Introduction to Algorithms</CITE>
+by T. Cormen, C. Leiserson, R. Rivest.
+1989 MIT Press.
+</P>
+<P>
+
+<A NAME="IDX1262"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>make-heap</B> <I>pred&lt;?</I>
+<DD><P>
+
+Returns a binary heap suitable which can be used for priority queue
+operations.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1263"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>heap-length</B> <I>heap</I>
+<DD><P>
+
+Returns the number of elements in <VAR>heap</VAR>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1264"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>heap-insert!</B> <I>heap item</I>
+<DD><P>
+
+Inserts <VAR>item</VAR> into <VAR>heap</VAR>. <VAR>item</VAR> can be inserted multiple
+times. The value returned is unspecified.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1265"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>heap-extract-max!</B> <I>heap</I>
+<DD><P>
+
+Returns the item which is larger than all others according to the
+<VAR>pred&lt;?</VAR> argument to <CODE>make-heap</CODE>. If there are no items in
+<VAR>heap</VAR>, an error is signaled.
+</P>
+</DL>
+<P>
+
+<A NAME="Queues"></A>
+<HR SIZE="6">
+<A NAME="SEC205"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC204"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC206"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.1.17 Queues </H3>
+<!--docid::SEC205::-->
+<P>
+
+<CODE>(require 'queue)</CODE>
+<A NAME="IDX1266"></A>
+</P>
+<P>
+
+A <EM>queue</EM> is a list where elements can be added to both the front
+<A NAME="IDX1267"></A>
+and rear, and removed from the front (i.e., they are what are often
+called <EM>dequeues</EM>). A queue may also be used like a stack.
+<A NAME="IDX1268"></A>
+</P>
+<P>
+
+<A NAME="IDX1269"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>make-queue</B>
+<DD><P>
+
+Returns a new, empty queue.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1270"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>queue?</B> <I>obj</I>
+<DD><P>
+
+Returns <CODE>#t</CODE> if <VAR>obj</VAR> is a queue.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1271"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>queue-empty?</B> <I>q</I>
+<DD><P>
+
+Returns <CODE>#t</CODE> if the queue <VAR>q</VAR> is empty.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1272"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>queue-push!</B> <I>q datum</I>
+<DD><P>
+
+Adds <VAR>datum</VAR> to the front of queue <VAR>q</VAR>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1273"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>enqueue!</B> <I>q datum</I>
+<DD><P>
+
+Adds <VAR>datum</VAR> to the rear of queue <VAR>q</VAR>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1274"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>dequeue!</B> <I>q</I>
+<DD><P>
+
+<A NAME="IDX1275"></A>
+<DT><U>Procedure:</U> <B>queue-pop!</B> <I>q</I>
+<DD>Both of these procedures remove and return the datum at the front of
+the queue. <CODE>queue-pop!</CODE> is used to suggest that the queue is
+being used like a stack.
+</P>
+</DL>
+All of the following functions raise an error if the queue <VAR>q</VAR>
+is empty.
+<P>
+
+<A NAME="IDX1276"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>dequeue-all!</B> <I>q</I>
+<DD><P>
+
+Removes and returns (the list) of all contents of queue <VAR>q</VAR>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1277"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>queue-front</B> <I>q</I>
+<DD><P>
+
+Returns the datum at the front of the queue <VAR>q</VAR>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1278"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>queue-rear</B> <I>q</I>
+<DD><P>
+
+Returns the datum at the rear of the queue <VAR>q</VAR>.
+</P>
+</DL>
+<P>
+
+<A NAME="Records"></A>
+<HR SIZE="6">
+<A NAME="SEC206"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC205"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC207"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC184"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.1.18 Records </H3>
+<!--docid::SEC206::-->
+<P>
+
+<CODE>(require 'record)</CODE>
+<A NAME="IDX1279"></A>
+</P>
+<P>
+
+The Record package provides a facility for user to define their own
+record data types.
+</P>
+<P>
+
+<A NAME="IDX1280"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>make-record-type</B> <I>type-name field-names</I>
+<DD>Returns a <EM>record-type descriptor</EM>, a value representing a new data
+type disjoint from all others. The <VAR>type-name</VAR> argument must be a
+string, but is only used for debugging purposes (such as the printed
+representation of a record of the new type). The <VAR>field-names</VAR>
+argument is a list of symbols naming the <EM>fields</EM> of a record of the
+new type. It is an error if the list contains any duplicates. It is
+unspecified how record-type descriptors are represented.
+</DL>
+<P>
+
+<A NAME="IDX1281"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>record-constructor</B> <I>rtd [field-names]</I>
+<DD>Returns a procedure for constructing new members of the type represented
+by <VAR>rtd</VAR>. The returned procedure accepts exactly as many arguments
+as there are symbols in the given list, <VAR>field-names</VAR>; these are
+used, in order, as the initial values of those fields in a new record,
+which is returned by the constructor procedure. The values of any
+fields not named in that list are unspecified. The <VAR>field-names</VAR>
+argument defaults to the list of field names in the call to
+<CODE>make-record-type</CODE> that created the type represented by <VAR>rtd</VAR>;
+if the <VAR>field-names</VAR> argument is provided, it is an error if it
+contains any duplicates or any symbols not in the default list.
+</DL>
+<P>
+
+<A NAME="IDX1282"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>record-predicate</B> <I>rtd</I>
+<DD>Returns a procedure for testing membership in the type represented by
+<VAR>rtd</VAR>. The returned procedure accepts exactly one argument and
+returns a true value if the argument is a member of the indicated record
+type; it returns a false value otherwise.
+</DL>
+<P>
+
+<A NAME="IDX1283"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>record-accessor</B> <I>rtd field-name</I>
+<DD>Returns a procedure for reading the value of a particular field of a
+member of the type represented by <VAR>rtd</VAR>. The returned procedure
+accepts exactly one argument which must be a record of the appropriate
+type; it returns the current value of the field named by the symbol
+<VAR>field-name</VAR> in that record. The symbol <VAR>field-name</VAR> must be a
+member of the list of field-names in the call to <CODE>make-record-type</CODE>
+that created the type represented by <VAR>rtd</VAR>.
+</DL>
+<P>
+
+<A NAME="IDX1284"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>record-modifier</B> <I>rtd field-name</I>
+<DD>Returns a procedure for writing the value of a particular field of a
+member of the type represented by <VAR>rtd</VAR>. The returned procedure
+accepts exactly two arguments: first, a record of the appropriate type,
+and second, an arbitrary Scheme value; it modifies the field named by
+the symbol <VAR>field-name</VAR> in that record to contain the given value.
+The returned value of the modifier procedure is unspecified. The symbol
+<VAR>field-name</VAR> must be a member of the list of field-names in the call
+to <CODE>make-record-type</CODE> that created the type represented by
+<VAR>rtd</VAR>.
+</DL>
+<P>
+
+In May of 1996, as a product of discussion on the <CODE>rrrs-authors</CODE>
+mailing list, I rewrote `<TT>record.scm</TT>' to portably implement type
+disjointness for record data types.
+</P>
+<P>
+
+As long as an implementation's procedures are opaque and the
+<CODE>record</CODE> code is loaded before other programs, this will give
+disjoint record types which are unforgeable and incorruptible by R4RS
+procedures.
+</P>
+<P>
+
+As a consequence, the procedures <CODE>record?</CODE>,
+<CODE>record-type-descriptor</CODE>, <CODE>record-type-name</CODE>.and
+<CODE>record-type-field-names</CODE> are no longer supported.
+</P>
+<P>
+
+<A NAME="Sorting and Searching"></A>
+<HR SIZE="6">
+<A NAME="SEC207"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC206"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC208"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H2> 7.2 Sorting and Searching </H2>
+<!--docid::SEC207::-->
+<P>
+
+<TABLE BORDER="0" CELLSPACING="0">
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC208">7.2.1 Common List Functions</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'common-list-functions</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC214">7.2.2 Tree operations</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'tree</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC215">7.2.3 Chapter Ordering</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'chapter-order</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC216">7.2.4 Sorting</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'sort</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC217">7.2.5 Topological Sort</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Keep your socks on.</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC218">7.2.6 Hashing</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'hash</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC219">7.2.7 Space-Filling Curves</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'hilbert and 'sierpinski</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC222">7.2.8 Soundex</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Dimension Reduction of Last Names</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC223">7.2.9 String Search</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Also Search from a Port.</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC224">7.2.10 Sequence Comparison</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'diff and longest-common-subsequence</TD></TR>
+</TABLE>
+<P>
+
+<A NAME="Common List Functions"></A>
+<HR SIZE="6">
+<A NAME="SEC208"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC207"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC209"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC207"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.2.1 Common List Functions </H3>
+<!--docid::SEC208::-->
+<P>
+
+<CODE>(require 'common-list-functions)</CODE>
+<A NAME="IDX1285"></A>
+</P>
+<P>
+
+The procedures below follow the Common LISP equivalents apart from
+optional arguments in some cases.
+</P>
+<P>
+
+<TABLE BORDER="0" CELLSPACING="0">
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC209">7.2.1.1 List construction</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC210">7.2.1.2 Lists as sets</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC211">7.2.1.3 Lists as sequences</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC212">7.2.1.4 Destructive list operations</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC213">7.2.1.5 Non-List functions</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
+</TABLE>
+<P>
+
+<A NAME="List construction"></A>
+<HR SIZE="6">
+<A NAME="SEC209"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC208"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC210"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC208"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H4> 7.2.1.1 List construction </H4>
+<!--docid::SEC209::-->
+<P>
+
+<A NAME="IDX1286"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>make-list</B> <I>k</I>
+<DD><A NAME="IDX1287"></A>
+<DT><U>Function:</U> <B>make-list</B> <I>k init</I>
+<DD><CODE>make-list</CODE> creates and returns a list of <VAR>k</VAR> elements. If
+<VAR>init</VAR> is included, all elements in the list are initialized to
+<VAR>init</VAR>.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(make-list 3)
+ => (#&lt;unspecified&gt; #&lt;unspecified&gt; #&lt;unspecified&gt;)
+(make-list 5 'foo)
+ => (foo foo foo foo foo)
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1288"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>list*</B> <I>obj1 obj2 <small>...</small></I>
+<DD>Works like <CODE>list</CODE> except that the cdr of the last pair is the last
+argument unless there is only one argument, when the result is just that
+argument. Sometimes called <CODE>cons*</CODE>. E.g.:
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(list* 1)
+ => 1
+(list* 1 2 3)
+ => (1 2 . 3)
+(list* 1 2 '(3 4))
+ => (1 2 3 4)
+(list* <VAR>args</VAR> '())
+ == (list <VAR>args</VAR>)
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1289"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>copy-list</B> <I>lst</I>
+<DD><CODE>copy-list</CODE> makes a copy of <VAR>lst</VAR> using new pairs and returns
+it. Only the top level of the list is copied, i.e., pairs forming
+elements of the copied list remain <CODE>eq?</CODE> to the corresponding
+elements of the original; the copy is, however, not <CODE>eq?</CODE> to the
+original, but is <CODE>equal?</CODE> to it.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(copy-list '(foo foo foo))
+ => (foo foo foo)
+(define q '(foo bar baz bang))
+(define p q)
+(eq? p q)
+ => #t
+(define r (copy-list q))
+(eq? q r)
+ => #f
+(equal? q r)
+ => #t
+(define bar '(bar))
+(eq? bar (car (copy-list (list bar 'foo))))
+=> #t
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="Lists as sets"></A>
+<HR SIZE="6">
+<A NAME="SEC210"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC209"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC211"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC208"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H4> 7.2.1.2 Lists as sets </H4>
+<!--docid::SEC210::-->
+<P>
+
+<CODE>eqv?</CODE> is used to test for membership by procedures which treat
+lists as sets.
+</P>
+<P>
+
+<A NAME="IDX1290"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>adjoin</B> <I>e l</I>
+<DD><CODE>adjoin</CODE> returns the adjoint of the element <VAR>e</VAR> and the list
+<VAR>l</VAR>. That is, if <VAR>e</VAR> is in <VAR>l</VAR>, <CODE>adjoin</CODE> returns
+<VAR>l</VAR>, otherwise, it returns <CODE>(cons <VAR>e</VAR> <VAR>l</VAR>)</CODE>.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(adjoin 'baz '(bar baz bang))
+ => (bar baz bang)
+(adjoin 'foo '(bar baz bang))
+ => (foo bar baz bang)
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1291"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>union</B> <I>l1 l2</I>
+<DD><CODE>union</CODE> returns a list of all elements that are in <VAR>l1</VAR> or
+<VAR>l2</VAR>. Duplicates between <VAR>l1</VAR> and <VAR>l2</VAR> are culled.
+Duplicates within <VAR>l1</VAR> or within <VAR>l2</VAR> may or may not be
+removed.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(union '(1 2 3 4) '(5 6 7 8))
+ => (1 2 3 4 5 6 7 8)
+(union '(0 1 2 3 4) '(3 4 5 6))
+ => (5 6 0 1 2 3 4)
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1292"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>intersection</B> <I>l1 l2</I>
+<DD><CODE>intersection</CODE> returns a list of all elements that are in both
+<VAR>l1</VAR> and <VAR>l2</VAR>.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(intersection '(1 2 3 4) '(3 4 5 6))
+ => (3 4)
+(intersection '(1 2 3 4) '(5 6 7 8))
+ => ()
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1293"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>set-difference</B> <I>l1 l2</I>
+<DD><CODE>set-difference</CODE> returns a list of all elements that are in
+<VAR>l1</VAR> but not in <VAR>l2</VAR>.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(set-difference '(1 2 3 4) '(3 4 5 6))
+ => (1 2)
+(set-difference '(1 2 3 4) '(1 2 3 4 5 6))
+ => ()
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1294"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>subset?</B> <I>list1 list2</I>
+<DD>Returns <CODE>#t</CODE> if every element of <VAR>list1</VAR> is <CODE>eqv?</CODE> an
+element of <VAR>list2</VAR>; otherwise returns <CODE>#f</CODE>.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(subset? '(1 2 3 4) '(3 4 5 6))
+ => #f
+(subset? '(1 2 3 4) '(6 5 4 3 2 1 0))
+ => #t
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1295"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>member-if</B> <I>pred lst</I>
+<DD><CODE>member-if</CODE> returns the list headed by the first element of
+<VAR>lst</VAR> to satisfy <CODE>(<VAR>pred</VAR> <VAR>element</VAR>)</CODE>.
+<CODE>Member-if</CODE> returns <CODE>#f</CODE> if <VAR>pred</VAR> returns <CODE>#f</CODE> for
+every <VAR>element</VAR> in <VAR>lst</VAR>.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(member-if vector? '(a 2 b 4))
+ => #f
+(member-if number? '(a 2 b 4))
+ => (2 b 4)
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1296"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>some</B> <I>pred lst1 lst2 <small>...</small></I>
+<DD><VAR>pred</VAR> is a boolean function of as many arguments as there are list
+arguments to <CODE>some</CODE> i.e., <VAR>lst</VAR> plus any optional arguments.
+<VAR>pred</VAR> is applied to successive elements of the list arguments in
+order. <CODE>some</CODE> returns <CODE>#t</CODE> as soon as one of these
+applications returns <CODE>#t</CODE>, and is <CODE>#f</CODE> if none returns
+<CODE>#t</CODE>. All the lists should have the same length.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(some odd? '(1 2 3 4))
+ => #t
+
+(some odd? '(2 4 6 8))
+ => #f
+
+(some &gt; '(1 3) '(2 4))
+ => #f
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1297"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>every</B> <I>pred lst1 lst2 <small>...</small></I>
+<DD><CODE>every</CODE> is analogous to <CODE>some</CODE> except it returns <CODE>#t</CODE> if
+every application of <VAR>pred</VAR> is <CODE>#t</CODE> and <CODE>#f</CODE>
+otherwise.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(every even? '(1 2 3 4))
+ => #f
+
+(every even? '(2 4 6 8))
+ => #t
+
+(every &gt; '(2 3) '(1 4))
+ => #f
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1298"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>notany</B> <I>pred lst1 <small>...</small></I>
+<DD><CODE>notany</CODE> is analogous to <CODE>some</CODE> but returns <CODE>#t</CODE> if no
+application of <VAR>pred</VAR> returns <CODE>#t</CODE> or <CODE>#f</CODE> as soon as any
+one does.
+</DL>
+<P>
+
+<A NAME="IDX1299"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>notevery</B> <I>pred lst1 <small>...</small></I>
+<DD><CODE>notevery</CODE> is analogous to <CODE>some</CODE> but returns <CODE>#t</CODE> as soon
+as an application of <VAR>pred</VAR> returns <CODE>#f</CODE>, and <CODE>#f</CODE>
+otherwise.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(notevery even? '(1 2 3 4))
+ => #t
+
+(notevery even? '(2 4 6 8))
+ => #f
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1300"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>list-of??</B> <I>predicate</I>
+<DD>Returns a predicate which returns true if its argument is a list every
+element of which satisfies <VAR>predicate</VAR>.
+<P>
+
+<A NAME="IDX1301"></A>
+<DT><U>Function:</U> <B>list-of??</B> <I>predicate low-bound high-bound</I>
+<DD><VAR>low-bound</VAR> and <VAR>high-bound</VAR> are non-negative integers.
+<CODE>list-of??</CODE> returns a predicate which returns true if its argument
+is a list of length between <VAR>low-bound</VAR> and <VAR>high-bound</VAR>
+(inclusive); every element of which satisfies <VAR>predicate</VAR>.
+</P>
+<P>
+
+<A NAME="IDX1302"></A>
+<DT><U>Function:</U> <B>list-of??</B> <I>predicate bound</I>
+<DD><VAR>bound</VAR> is an integer. If <VAR>bound</VAR> is negative, <CODE>list-of??</CODE>
+returns a predicate which returns true if its argument is a list of
+length greater than <CODE>(- <VAR>bound</VAR>)</CODE>; every element of which
+satisfies <VAR>predicate</VAR>. Otherwise, <CODE>list-of??</CODE> returns a
+predicate which returns true if its argument is a list of length less
+than or equal to <VAR>bound</VAR>; every element of which satisfies
+<VAR>predicate</VAR>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1303"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>find-if</B> <I>pred lst</I>
+<DD><CODE>find-if</CODE> searches for the first <VAR>element</VAR> in <VAR>lst</VAR> such
+that <CODE>(<VAR>pred</VAR> <VAR>element</VAR>)</CODE> returns <CODE>#t</CODE>. If it finds
+any such <VAR>element</VAR> in <VAR>lst</VAR>, <VAR>element</VAR> is returned.
+Otherwise, <CODE>#f</CODE> is returned.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(find-if number? '(foo 1 bar 2))
+ => 1
+
+(find-if number? '(foo bar baz bang))
+ => #f
+
+(find-if symbol? '(1 2 foo bar))
+ => foo
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1304"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>remove</B> <I>elt lst</I>
+<DD><CODE>remove</CODE> removes all occurrences of <VAR>elt</VAR> from <VAR>lst</VAR> using
+<CODE>eqv?</CODE> to test for equality and returns everything that's left.
+N.B.: other implementations (Chez, Scheme-&gt;C and T, at least) use
+<CODE>equal?</CODE> as the equality test.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(remove 1 '(1 2 1 3 1 4 1 5))
+ => (2 3 4 5)
+
+(remove 'foo '(bar baz bang))
+ => (bar baz bang)
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1305"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>remove-if</B> <I>pred lst</I>
+<DD><CODE>remove-if</CODE> removes all <VAR>element</VAR>s from <VAR>lst</VAR> where
+<CODE>(<VAR>pred</VAR> <VAR>element</VAR>)</CODE> is <CODE>#t</CODE> and returns everything
+that's left.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(remove-if number? '(1 2 3 4))
+ => ()
+
+(remove-if even? '(1 2 3 4 5 6 7 8))
+ => (1 3 5 7)
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1306"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>remove-if-not</B> <I>pred lst</I>
+<DD><CODE>remove-if-not</CODE> removes all <VAR>element</VAR>s from <VAR>lst</VAR> for which
+<CODE>(<VAR>pred</VAR> <VAR>element</VAR>)</CODE> is <CODE>#f</CODE> and returns everything that's
+left.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(remove-if-not number? '(foo bar baz))
+ => ()
+(remove-if-not odd? '(1 2 3 4 5 6 7 8))
+ => (1 3 5 7)
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1307"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>has-duplicates?</B> <I>lst</I>
+<DD>returns <CODE>#t</CODE> if 2 members of <VAR>lst</VAR> are <CODE>equal?</CODE>, <CODE>#f</CODE>
+otherwise.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(has-duplicates? '(1 2 3 4))
+ => #f
+
+(has-duplicates? '(2 4 3 4))
+ => #t
+</pre></td></tr></table></DL>
+<P>
+
+The procedure <CODE>remove-duplicates</CODE> uses <CODE>member</CODE> (rather than
+<CODE>memv</CODE>).
+</P>
+<P>
+
+<A NAME="IDX1308"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>remove-duplicates</B> <I>lst</I>
+<DD>returns a copy of <VAR>lst</VAR> with its duplicate members removed.
+Elements are considered duplicate if they are <CODE>equal?</CODE>.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(remove-duplicates '(1 2 3 4))
+ => (1 2 3 4)
+
+(remove-duplicates '(2 4 3 4))
+ => (2 4 3)
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="Lists as sequences"></A>
+<HR SIZE="6">
+<A NAME="SEC211"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC210"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC212"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC208"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H4> 7.2.1.3 Lists as sequences </H4>
+<!--docid::SEC211::-->
+<P>
+
+<A NAME="IDX1309"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>position</B> <I>obj lst</I>
+<DD><CODE>position</CODE> returns the 0-based position of <VAR>obj</VAR> in <VAR>lst</VAR>,
+or <CODE>#f</CODE> if <VAR>obj</VAR> does not occur in <VAR>lst</VAR>.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(position 'foo '(foo bar baz bang))
+ => 0
+(position 'baz '(foo bar baz bang))
+ => 2
+(position 'oops '(foo bar baz bang))
+ => #f
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1310"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>reduce</B> <I>p lst</I>
+<DD><CODE>reduce</CODE> combines all the elements of a sequence using a binary
+operation (the combination is left-associative). For example, using
+<CODE>+</CODE>, one can add up all the elements. <CODE>reduce</CODE> allows you to
+apply a function which accepts only two arguments to more than 2
+objects. Functional programmers usually refer to this as <EM>foldl</EM>.
+<CODE>collect:reduce</CODE> (see section <A HREF="slib_7.html#SEC194">7.1.9 Collections</A>) provides a version of
+<CODE>collect</CODE> generalized to collections.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(reduce + '(1 2 3 4))
+ => 10
+(define (bad-sum . l) (reduce + l))
+(bad-sum 1 2 3 4)
+ == (reduce + (1 2 3 4))
+ == (+ (+ (+ 1 2) 3) 4)
+=> 10
+(bad-sum)
+ == (reduce + ())
+ => ()
+(reduce string-append '(&quot;hello&quot; &quot;cruel&quot; &quot;world&quot;))
+ == (string-append (string-append &quot;hello&quot; &quot;cruel&quot;) &quot;world&quot;)
+ => &quot;hellocruelworld&quot;
+(reduce anything '())
+ => ()
+(reduce anything '(x))
+ => x
+</pre></td></tr></table><P>
+
+What follows is a rather non-standard implementation of <CODE>reverse</CODE>
+in terms of <CODE>reduce</CODE> and a combinator elsewhere called
+<EM>C</EM>.
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>;;; Contributed by Jussi Piitulainen (jpiitula @ ling.helsinki.fi)
+
+(define commute
+ (lambda (f)
+ (lambda (x y)
+ (f y x))))
+
+(define reverse
+ (lambda (args)
+ (reduce-init (commute cons) '() args)))
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1311"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>reduce-init</B> <I>p init lst</I>
+<DD><CODE>reduce-init</CODE> is the same as reduce, except that it implicitly
+inserts <VAR>init</VAR> at the start of the list. <CODE>reduce-init</CODE> is
+preferred if you want to handle the null list, the one-element, and
+lists with two or more elements consistently. It is common to use the
+operator's idempotent as the initializer. Functional programmers
+usually call this <EM>foldl</EM>.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define (sum . l) (reduce-init + 0 l))
+(sum 1 2 3 4)
+ == (reduce-init + 0 (1 2 3 4))
+ == (+ (+ (+ (+ 0 1) 2) 3) 4)
+ => 10
+(sum)
+ == (reduce-init + 0 '())
+ => 0
+
+(reduce-init string-append &quot;@&quot; '(&quot;hello&quot; &quot;cruel&quot; &quot;world&quot;))
+==
+(string-append (string-append (string-append &quot;@&quot; &quot;hello&quot;)
+ &quot;cruel&quot;)
+ &quot;world&quot;)
+=> &quot;@hellocruelworld&quot;
+</pre></td></tr></table><P>
+
+Given a differentiation of 2 arguments, <CODE>diff</CODE>, the following will
+differentiate by any number of variables.
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define (diff* exp . vars)
+ (reduce-init diff exp vars))
+</pre></td></tr></table><P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>;;; Real-world example: Insertion sort using reduce-init.
+
+(define (insert l item)
+ (if (null? l)
+ (list item)
+ (if (&lt; (car l) item)
+ (cons (car l) (insert (cdr l) item))
+ (cons item l))))
+(define (insertion-sort l) (reduce-init insert '() l))
+
+(insertion-sort '(3 1 4 1 5)
+ == (reduce-init insert () (3 1 4 1 5))
+ == (insert (insert (insert (insert (insert () 3) 1) 4) 1) 5)
+ == (insert (insert (insert (insert (3)) 1) 4) 1) 5)
+ == (insert (insert (insert (1 3) 4) 1) 5)
+ == (insert (insert (1 3 4) 1) 5)
+ == (insert (1 1 3 4) 5)
+ => (1 1 3 4 5)
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1312"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>last</B> <I>lst n</I>
+<DD><CODE>last</CODE> returns the last <VAR>n</VAR> elements of <VAR>lst</VAR>. <VAR>n</VAR>
+must be a non-negative integer.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(last '(foo bar baz bang) 2)
+ => (baz bang)
+(last '(1 2 3) 0)
+ => 0
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1313"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>butlast</B> <I>lst n</I>
+<DD><CODE>butlast</CODE> returns all but the last <VAR>n</VAR> elements of
+<VAR>lst</VAR>.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(butlast '(a b c d) 3)
+ => (a)
+(butlast '(a b c d) 4)
+ => ()
+</pre></td></tr></table></DL>
+<P>
+
+<CODE>last</CODE> and <CODE>butlast</CODE> split a list into two parts when given
+identical arugments.
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(last '(a b c d e) 2)
+ => (d e)
+(butlast '(a b c d e) 2)
+ => (a b c)
+</pre></td></tr></table><P>
+
+<A NAME="IDX1314"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>nthcdr</B> <I>n lst</I>
+<DD><CODE>nthcdr</CODE> takes <VAR>n</VAR> <CODE>cdr</CODE>s of <VAR>lst</VAR> and returns the
+result. Thus <CODE>(nthcdr 3 <VAR>lst</VAR>)</CODE> == <CODE>(cdddr
+<VAR>lst</VAR>)</CODE>
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(nthcdr 2 '(a b c d))
+ => (c d)
+(nthcdr 0 '(a b c d))
+ => (a b c d)
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1315"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>butnthcdr</B> <I>n lst</I>
+<DD><CODE>butnthcdr</CODE> returns all but the nthcdr <VAR>n</VAR> elements of
+<VAR>lst</VAR>.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(butnthcdr 3 '(a b c d))
+ => (a b c)
+(butnthcdr 4 '(a b c d))
+ => (a b c d)
+</pre></td></tr></table></DL>
+<P>
+
+<CODE>nthcdr</CODE> and <CODE>butnthcdr</CODE> split a list into two parts when
+given identical arugments.
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(nthcdr 2 '(a b c d e))
+ => (c d e)
+(butnthcdr 2 '(a b c d e))
+ => (a b)
+</pre></td></tr></table><P>
+
+<A NAME="Destructive list operations"></A>
+<HR SIZE="6">
+<A NAME="SEC212"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC211"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC213"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC208"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H4> 7.2.1.4 Destructive list operations </H4>
+<!--docid::SEC212::-->
+<P>
+
+These procedures may mutate the list they operate on, but any such
+mutation is undefined.
+</P>
+<P>
+
+<A NAME="IDX1316"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>nconc</B> <I>args</I>
+<DD><CODE>nconc</CODE> destructively concatenates its arguments. (Compare this
+with <CODE>append</CODE>, which copies arguments rather than destroying them.)
+Sometimes called <CODE>append!</CODE> (see section <A HREF="slib_7.html#SEC239">7.4.4 Rev2 Procedures</A>).
+<P>
+
+Example: You want to find the subsets of a set. Here's the obvious way:
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define (subsets set)
+ (if (null? set)
+ '(())
+ (append (map (lambda (sub) (cons (car set) sub))
+ (subsets (cdr set)))
+ (subsets (cdr set)))))
+</pre></td></tr></table>But that does way more consing than you need. Instead, you could
+replace the <CODE>append</CODE> with <CODE>nconc</CODE>, since you don't have any
+need for all the intermediate results.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define x '(a b c))
+(define y '(d e f))
+(nconc x y)
+ => (a b c d e f)
+x
+ => (a b c d e f)
+</pre></td></tr></table><P>
+
+<CODE>nconc</CODE> is the same as <CODE>append!</CODE> in `<TT>sc2.scm</TT>'.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1317"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>nreverse</B> <I>lst</I>
+<DD><CODE>nreverse</CODE> reverses the order of elements in <VAR>lst</VAR> by mutating
+<CODE>cdr</CODE>s of the list. Sometimes called <CODE>reverse!</CODE>.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define foo '(a b c))
+(nreverse foo)
+ => (c b a)
+foo
+ => (a)
+</pre></td></tr></table><P>
+
+Some people have been confused about how to use <CODE>nreverse</CODE>,
+thinking that it doesn't return a value. It needs to be pointed out
+that
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(set! lst (nreverse lst))
+</pre></td></tr></table>is the proper usage, not
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(nreverse lst)
+</pre></td></tr></table>The example should suffice to show why this is the case.
+</DL>
+<P>
+
+<A NAME="IDX1318"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>delete</B> <I>elt lst</I>
+<DD><A NAME="IDX1319"></A>
+<DT><U>Procedure:</U> <B>delete-if</B> <I>pred lst</I>
+<DD><A NAME="IDX1320"></A>
+<DT><U>Procedure:</U> <B>delete-if-not</B> <I>pred lst</I>
+<DD>Destructive versions of <CODE>remove</CODE> <CODE>remove-if</CODE>, and
+<CODE>remove-if-not</CODE>.
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define lst (list 'foo 'bar 'baz 'bang))
+(delete 'foo lst)
+ => (bar baz bang)
+lst
+ => (foo bar baz bang)
+
+(define lst (list 1 2 3 4 5 6 7 8 9))
+(delete-if odd? lst)
+ => (2 4 6 8)
+lst
+ => (1 2 4 6 8)
+</pre></td></tr></table><P>
+
+Some people have been confused about how to use <CODE>delete</CODE>,
+<CODE>delete-if</CODE>, and <CODE>delete-if</CODE>, thinking that they don't return
+a value. It needs to be pointed out that
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(set! lst (delete el lst))
+</pre></td></tr></table>is the proper usage, not
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(delete el lst)
+</pre></td></tr></table>The examples should suffice to show why this is the case.
+</DL>
+<P>
+
+<A NAME="Non-List functions"></A>
+<HR SIZE="6">
+<A NAME="SEC213"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC212"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC214"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC208"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H4> 7.2.1.5 Non-List functions </H4>
+<!--docid::SEC213::-->
+<P>
+
+<A NAME="IDX1321"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>and?</B> <I>arg1 <small>...</small></I>
+<DD><CODE>and?</CODE> checks to see if all its arguments are true. If they are,
+<CODE>and?</CODE> returns <CODE>#t</CODE>, otherwise, <CODE>#f</CODE>. (In contrast to
+<CODE>and</CODE>, this is a function, so all arguments are always evaluated
+and in an unspecified order.)
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(and? 1 2 3)
+ => #t
+(and #f 1 2)
+ => #f
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1322"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>or?</B> <I>arg1 <small>...</small></I>
+<DD><CODE>or?</CODE> checks to see if any of its arguments are true. If any is
+true, <CODE>or?</CODE> returns <CODE>#t</CODE>, and <CODE>#f</CODE> otherwise. (To
+<CODE>or</CODE> as <CODE>and?</CODE> is to <CODE>and</CODE>.)
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(or? 1 2 #f)
+ => #t
+(or? #f #f #f)
+ => #f
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1323"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>atom?</B> <I>object</I>
+<DD>Returns <CODE>#t</CODE> if <VAR>object</VAR> is not a pair and <CODE>#f</CODE> if it is
+pair. (Called <CODE>atom</CODE> in Common LISP.)
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(atom? 1)
+ => #t
+(atom? '(1 2))
+ => #f
+(atom? #(1 2)) ; dubious!
+ => #t
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="Tree Operations"></A>
+<HR SIZE="6">
+<A NAME="SEC214"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC213"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC215"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC207"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.2.2 Tree operations </H3>
+<!--docid::SEC214::-->
+<P>
+
+<CODE>(require 'tree)</CODE>
+<A NAME="IDX1324"></A>
+</P>
+<P>
+
+These are operations that treat lists a representations of trees.
+</P>
+<P>
+
+<A NAME="IDX1325"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>subst</B> <I>new old tree</I>
+<DD><A NAME="IDX1326"></A>
+<DT><U>Function:</U> <B>substq</B> <I>new old tree</I>
+<DD><A NAME="IDX1327"></A>
+<DT><U>Function:</U> <B>substv</B> <I>new old tree</I>
+<DD><P>
+
+<A NAME="IDX1328"></A>
+<DT><U>Function:</U> <B>subst</B> <I>new old tree equ?</I>
+<DD><CODE>subst</CODE> makes a copy of <VAR>tree</VAR>, substituting <VAR>new</VAR> for
+every subtree or leaf of <VAR>tree</VAR> which is <CODE>equal?</CODE> to <VAR>old</VAR>
+and returns a modified tree. The original <VAR>tree</VAR> is unchanged, but
+may share parts with the result.
+</P>
+<P>
+
+<CODE>substq</CODE> and <CODE>substv</CODE> are similar, but test against <VAR>old</VAR>
+using <CODE>eq?</CODE> and <CODE>eqv?</CODE> respectively. If <CODE>subst</CODE> is
+called with a fourth argument, <VAR>equ?</VAR> is the equality predicate.
+</P>
+<P>
+
+Examples:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(substq 'tempest 'hurricane '(shakespeare wrote (the hurricane)))
+ => (shakespeare wrote (the tempest))
+(substq 'foo '() '(shakespeare wrote (twelfth night)))
+ => (shakespeare wrote (twelfth night . foo) . foo)
+(subst '(a . cons) '(old . pair)
+ '((old . spice) ((old . shoes) old . pair) (old . pair)))
+ => ((old . spice) ((old . shoes) a . cons) (a . cons))
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1329"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>copy-tree</B> <I>tree</I>
+<DD><P>
+
+Makes a copy of the nested list structure <VAR>tree</VAR> using new pairs and
+returns it. All levels are copied, so that none of the pairs in the
+tree are <CODE>eq?</CODE> to the original ones -- only the leaves are.
+</P>
+<P>
+
+Example:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define bar '(bar))
+(copy-tree (list bar 'foo))
+ => ((bar) foo)
+(eq? bar (car (copy-tree (list bar 'foo))))
+ => #f
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="Chapter Ordering"></A>
+<HR SIZE="6">
+<A NAME="SEC215"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC214"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC216"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC207"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.2.3 Chapter Ordering </H3>
+<!--docid::SEC215::-->
+<P>
+
+<CODE>(require 'chapter-order)</CODE>
+<A NAME="IDX1330"></A>
+</P>
+<P>
+
+The `<SAMP>chap:</SAMP>' functions deal with strings which are ordered like
+chapter numbers (or letters) in a book. Each section of the string
+consists of consecutive numeric or consecutive aphabetic characters of
+like case.
+</P>
+<P>
+
+<A NAME="IDX1331"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>chap:string&lt;?</B> <I>string1 string2</I>
+<DD><P>
+
+Returns #t if the first non-matching run of alphabetic upper-case or
+the first non-matching run of alphabetic lower-case or the first
+non-matching run of numeric characters of <VAR>string1</VAR> is
+<CODE>string&lt;?</CODE> than the corresponding non-matching run of
+characters of <VAR>string2</VAR>.
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(chap:string&lt;? &quot;a.9&quot; &quot;a.10&quot;) => #t
+(chap:string&lt;? &quot;4c&quot; &quot;4aa&quot;) => #t
+(chap:string&lt;? &quot;Revised^{3.99}&quot; &quot;Revised^{4}&quot;) => #t
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1332"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>chap:string&gt;?</B> <I>string1 string2</I>
+<DD><A NAME="IDX1333"></A>
+<DT><U>Function:</U> <B>chap:string&lt;=?</B> <I>string1 string2</I>
+<DD><A NAME="IDX1334"></A>
+<DT><U>Function:</U> <B>chap:string&gt;=?</B> <I>string1 string2</I>
+<DD><P>
+
+Implement the corresponding chapter-order predicates.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1335"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>chap:next-string</B> <I>string</I>
+<DD><P>
+
+Returns the next string in the <EM>chapter order</EM>. If <VAR>string</VAR>
+has no alphabetic or numeric characters,
+<CODE>(string-append <VAR>string</VAR> &quot;0&quot;)</CODE> is returnd. The argument to
+chap:next-string will always be <CODE>chap:string&lt;?</CODE> than the result.
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(chap:next-string &quot;a.9&quot;) => &quot;a.10&quot;
+(chap:next-string &quot;4c&quot;) => &quot;4d&quot;
+(chap:next-string &quot;4z&quot;) => &quot;4aa&quot;
+(chap:next-string &quot;Revised^{4}&quot;) => &quot;Revised^{5}&quot;
+
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="Sorting"></A>
+<HR SIZE="6">
+<A NAME="SEC216"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC215"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC217"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC207"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.2.4 Sorting </H3>
+<!--docid::SEC216::-->
+<P>
+
+<CODE>(require 'sort)</CODE>
+<A NAME="IDX1336"></A>
+</P>
+<P>
+
+Many Scheme systems provide some kind of sorting functions. They do
+not, however, always provide the <EM>same</EM> sorting functions, and
+those that I have had the opportunity to test provided inefficient ones
+(a common blunder is to use quicksort which does not perform well).
+</P>
+<P>
+
+Because <CODE>sort</CODE> and <CODE>sort!</CODE> are not in the standard, there is
+very little agreement about what these functions look like. For
+example, Dybvig says that Chez Scheme provides
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(merge predicate list1 list2)
+(merge! predicate list1 list2)
+(sort predicate list)
+(sort! predicate list)
+</pre></td></tr></table>while MIT Scheme 7.1, following Common LISP, offers unstable
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(sort list predicate)
+</pre></td></tr></table>TI PC Scheme offers
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(sort! list/vector predicate?)
+</pre></td></tr></table>and Elk offers
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(sort list/vector predicate?)
+(sort! list/vector predicate?)
+</pre></td></tr></table><P>
+
+Here is a comprehensive catalogue of the variations I have found.
+</P>
+<P>
+
+<OL>
+<LI>
+Both <CODE>sort</CODE> and <CODE>sort!</CODE> may be provided.
+<LI>
+<CODE>sort</CODE> may be provided without <CODE>sort!</CODE>.
+<LI>
+<CODE>sort!</CODE> may be provided without <CODE>sort</CODE>.
+<LI>
+Neither may be provided.
+<LI>
+The sequence argument may be either a list or a vector.
+<LI>
+The sequence argument may only be a list.
+<LI>
+The sequence argument may only be a vector.
+<LI>
+The comparison function may be expected to behave like <CODE>&lt;</CODE>.
+<LI>
+The comparison function may be expected to behave like <CODE>&lt;=</CODE>.
+<LI>
+The interface may be <CODE>(sort predicate? sequence)</CODE>.
+<LI>
+The interface may be <CODE>(sort sequence predicate?)</CODE>.
+<LI>
+The interface may be <CODE>(sort sequence &amp;optional (predicate? &lt;))</CODE>.
+<LI>
+The sort may be stable.
+<LI>
+The sort may be unstable.
+</OL>
+<P>
+
+All of this variation really does not help anybody. A nice simple merge
+sort is both stable and fast (quite a lot faster than <EM>quick</EM> sort).
+</P>
+<P>
+
+I am providing this source code with no restrictions at all on its use
+(but please retain D.H.D.Warren's credit for the original idea). You
+may have to rename some of these functions in order to use them in a
+system which already provides incompatible or inferior sorts. For each
+of the functions, only the top-level define needs to be edited to do
+that.
+</P>
+<P>
+
+I could have given these functions names which would not clash with any
+Scheme that I know of, but I would like to encourage implementors to
+converge on a single interface, and this may serve as a hint. The
+argument order for all functions has been chosen to be as close to
+Common LISP as made sense, in order to avoid NIH-itis.
+</P>
+<P>
+
+Each of the five functions has a required <EM>last</EM> parameter which is
+a comparison function. A comparison function <CODE>f</CODE> is a function of
+2 arguments which acts like <CODE>&lt;</CODE>. For example,
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(not (f x x))
+(and (f x y) (f y z)) == (f x z)
+</pre></td></tr></table><P>
+
+The standard functions <CODE>&lt;</CODE>, <CODE>&gt;</CODE>, <CODE>char&lt;?</CODE>, <CODE>char&gt;?</CODE>,
+<CODE>char-ci&lt;?</CODE>, <CODE>char-ci&gt;?</CODE>, <CODE>string&lt;?</CODE>, <CODE>string&gt;?</CODE>,
+<CODE>string-ci&lt;?</CODE>, and <CODE>string-ci&gt;?</CODE> are suitable for use as
+comparison functions. Think of <CODE>(less? x y)</CODE> as saying when
+<CODE>x</CODE> must <EM>not</EM> precede <CODE>y</CODE>.
+</P>
+<P>
+
+<A NAME="IDX1337"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>sorted?</B> <I>sequence less?</I>
+<DD>Returns <CODE>#t</CODE> when the sequence argument is in non-decreasing order
+according to <VAR>less?</VAR> (that is, there is no adjacent pair <CODE><small>...</small> x
+y <small>...</small></CODE> for which <CODE>(less? y x)</CODE>).
+<P>
+
+Returns <CODE>#f</CODE> when the sequence contains at least one out-of-order
+pair. It is an error if the sequence is not a list, vector, or
+string.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1338"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>merge</B> <I>list1 list2 less?</I>
+<DD>This merges two lists, producing a completely new list as result. I
+gave serious consideration to producing a Common-LISP-compatible
+version. However, Common LISP's <CODE>sort</CODE> is our <CODE>sort!</CODE> (well,
+in fact Common LISP's <CODE>stable-sort</CODE> is our <CODE>sort!</CODE>, merge sort
+is <EM>fast</EM> as well as stable!) so adapting CL code to Scheme takes a
+bit of work anyway. I did, however, appeal to CL to determine the
+<EM>order</EM> of the arguments.
+</DL>
+<P>
+
+<A NAME="IDX1339"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>merge!</B> <I>list1 list2 less?</I>
+<DD>Merges two lists, re-using the pairs of <VAR>list1</VAR> and <VAR>list2</VAR> to
+build the result. If the code is compiled, and <VAR>less?</VAR> constructs
+no new pairs, no pairs at all will be allocated. The first pair of the
+result will be either the first pair of <VAR>list1</VAR> or the first pair of
+<VAR>list2</VAR>, but you can't predict which.
+<P>
+
+The code of <CODE>merge</CODE> and <CODE>merge!</CODE> could have been quite a bit
+simpler, but they have been coded to reduce the amount of work done per
+iteration. (For example, we only have one <CODE>null?</CODE> test per
+iteration.)
+</P>
+<P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1340"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>sort</B> <I>sequence less?</I>
+<DD>Accepts either a list, vector, or string; and returns a new sequence
+which is sorted. The new sequence is the same type as the input.
+Always <CODE>(sorted? (sort sequence less?) less?)</CODE>. The original
+sequence is not altered in any way. The new sequence shares its
+<EM>elements</EM> with the old one; no elements are copied.
+</DL>
+<P>
+
+<A NAME="IDX1341"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>sort!</B> <I>sequence less?</I>
+<DD>Returns its sorted result in the original boxes. If the original
+sequence is a list, no new storage is allocated at all. If the
+original sequence is a vector or string, the sorted elements are put
+back in the same vector or string.
+<P>
+
+Some people have been confused about how to use <CODE>sort!</CODE>, thinking
+that it doesn't return a value. It needs to be pointed out that
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(set! slist (sort! slist &lt;))
+</pre></td></tr></table>is the proper usage, not
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(sort! slist &lt;)
+</pre></td></tr></table></DL>
+<P>
+
+Note that these functions do <EM>not</EM> accept a CL-style `<SAMP>:key</SAMP>'
+argument. A simple device for obtaining the same expressiveness is to
+define
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define (keyed less? key)
+ (lambda (x y) (less? (key x) (key y))))
+</pre></td></tr></table>and then, when you would have written
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(sort a-sequence #'my-less :key #'my-key)
+</pre></td></tr></table>in Common LISP, just write
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(sort! a-sequence (keyed my-less? my-key))
+</pre></td></tr></table>in Scheme.
+<P>
+
+<A NAME="Topological Sort"></A>
+<HR SIZE="6">
+<A NAME="SEC217"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC216"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC218"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC207"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.2.5 Topological Sort </H3>
+<!--docid::SEC217::-->
+<P>
+
+<CODE>(require 'topological-sort)</CODE> or <CODE>(require 'tsort)</CODE>
+<A NAME="IDX1342"></A>
+<A NAME="IDX1343"></A>
+</P>
+<P>
+
+The algorithm is inspired by Cormen, Leiserson and Rivest (1990)
+<CITE>Introduction to Algorithms</CITE>, chapter 23.
+</P>
+<P>
+
+<A NAME="IDX1344"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>tsort</B> <I>dag pred</I>
+<DD><P>
+
+<A NAME="IDX1345"></A>
+<DT><U>Function:</U> <B>topological-sort</B> <I>dag pred</I>
+<DD>where
+</P>
+<DL COMPACT>
+<DT><VAR>dag</VAR>
+<DD>is a list of sublists. The car of each sublist is a vertex. The cdr is
+the adjacency list of that vertex, i.e. a list of all vertices to which
+there exists an edge from the car vertex.
+<DT><VAR>pred</VAR>
+<DD>is one of <CODE>eq?</CODE>, <CODE>eqv?</CODE>, <CODE>equal?</CODE>, <CODE>=</CODE>,
+<CODE>char=?</CODE>, <CODE>char-ci=?</CODE>, <CODE>string=?</CODE>, or <CODE>string-ci=?</CODE>.
+</DL>
+<P>
+
+Sort the directed acyclic graph <VAR>dag</VAR> so that for every edge from
+vertex <VAR>u</VAR> to <VAR>v</VAR>, <VAR>u</VAR> will come before <VAR>v</VAR> in the
+resulting list of vertices.
+</P>
+<P>
+
+Time complexity: O (|V| + |E|)
+</P>
+<P>
+
+Example (from Cormen):
+<BLOCKQUOTE>
+Prof. Bumstead topologically sorts his clothing when getting
+dressed. The first argument to <CODE>tsort</CODE> describes which
+garments he needs to put on before others. (For example,
+Prof Bumstead needs to put on his shirt before he puts on his
+tie or his belt.) <CODE>tsort</CODE> gives the correct order of dressing:
+</BLOCKQUOTE>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(require 'tsort)
+<A NAME="IDX1346"></A>(tsort '((shirt tie belt)
+ (tie jacket)
+ (belt jacket)
+ (watch)
+ (pants shoes belt)
+ (undershorts pants shoes)
+ (socks shoes))
+ eq?)
+=>
+(socks undershorts pants shoes watch shirt belt tie jacket)
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="Hashing"></A>
+<HR SIZE="6">
+<A NAME="SEC218"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC217"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC219"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC207"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.2.6 Hashing </H3>
+<!--docid::SEC218::-->
+<P>
+
+<CODE>(require 'hash)</CODE>
+<A NAME="IDX1347"></A>
+</P>
+<P>
+
+These hashing functions are for use in quickly classifying objects.
+Hash tables use these functions.
+</P>
+<P>
+
+<A NAME="IDX1348"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>hashq</B> <I>obj k</I>
+<DD><A NAME="IDX1349"></A>
+<DT><U>Function:</U> <B>hashv</B> <I>obj k</I>
+<DD><A NAME="IDX1350"></A>
+<DT><U>Function:</U> <B>hash</B> <I>obj k</I>
+<DD>Returns an exact non-negative integer less than <VAR>k</VAR>. For each
+non-negative integer less than <VAR>k</VAR> there are arguments <VAR>obj</VAR> for
+which the hashing functions applied to <VAR>obj</VAR> and <VAR>k</VAR> returns
+that integer.
+<P>
+
+For <CODE>hashq</CODE>, <CODE>(eq? obj1 obj2)</CODE> implies <CODE>(= (hashq obj1 k)
+(hashq obj2))</CODE>.
+</P>
+<P>
+
+For <CODE>hashv</CODE>, <CODE>(eqv? obj1 obj2)</CODE> implies <CODE>(= (hashv obj1 k)
+(hashv obj2))</CODE>.
+</P>
+<P>
+
+For <CODE>hash</CODE>, <CODE>(equal? obj1 obj2)</CODE> implies <CODE>(= (hash obj1 k)
+(hash obj2))</CODE>.
+</P>
+<P>
+
+<CODE>hash</CODE>, <CODE>hashv</CODE>, and <CODE>hashq</CODE> return in time bounded by a
+constant. Notice that items having the same <CODE>hash</CODE> implies the
+items have the same <CODE>hashv</CODE> implies the items have the same
+<CODE>hashq</CODE>.
+</P>
+</DL>
+<P>
+
+<A NAME="Space-Filling Curves"></A>
+<HR SIZE="6">
+<A NAME="SEC219"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC218"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC220"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC207"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.2.7 Space-Filling Curves </H3>
+<!--docid::SEC219::-->
+<P>
+
+<TABLE BORDER="0" CELLSPACING="0">
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC220">7.2.7.1 Peano-Hilbert Space-Filling Curve</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC221">7.2.7.2 Sierpinski Curve</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
+</TABLE>
+<P>
+
+<A NAME="Peano-Hilbert Space-Filling Curve"></A>
+<HR SIZE="6">
+<A NAME="SEC220"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC219"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC221"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC219"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H4> 7.2.7.1 Peano-Hilbert Space-Filling Curve </H4>
+<!--docid::SEC220::-->
+<P>
+
+<CODE>(require 'hilbert-fill)</CODE>
+<A NAME="IDX1351"></A>
+</P>
+<P>
+
+<A NAME="IDX1352"></A>
+<A NAME="IDX1353"></A>
+<A NAME="IDX1354"></A>
+The <EM>Peano-Hilbert Space-Filling Curve</EM> is a one-to-one mapping
+<A NAME="IDX1355"></A>
+between a unit line segment and an <VAR>n</VAR>-dimensional unit cube.
+</P>
+<P>
+
+The integer procedures map the non-negative integers to an
+arbitrarily large <VAR>n</VAR>-dimensional cube with its corner at the
+origin and all coordinates are non-negative.
+</P>
+<P>
+
+For any exact nonnegative integers <VAR>scalar</VAR> and <VAR>rank</VAR>,
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(= <VAR>scalar</VAR> (hilbert-coordinates-&gt;integer
+ (integer-&gt;hilbert-coordinates <VAR>scalar</VAR> <VAR>rank</VAR>)))
+ => #t
+</pre></td></tr></table><P>
+
+<A NAME="IDX1356"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>integer-&gt;hilbert-coordinates</B> <I>scalar rank</I>
+<DD><P>
+
+Returns a list of <VAR>rank</VAR> integer coordinates corresponding to exact
+non-negative integer <VAR>scalar</VAR>. The lists returned by <CODE>integer-&gt;hilbert-coordinates</CODE> for <VAR>scalar</VAR> arguments
+0 and 1 will differ in the first element.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1357"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>hilbert-coordinates-&gt;integer</B> <I>coords</I>
+<DD><P>
+
+Returns an exact non-negative integer corresponding to <VAR>coords</VAR>, a list
+of non-negative integer coordinates.
+</P>
+</DL>
+<P>
+
+<A NAME="Sierpinski Curve"></A>
+<HR SIZE="6">
+<A NAME="SEC221"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC220"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC222"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC219"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H4> 7.2.7.2 Sierpinski Curve </H4>
+<!--docid::SEC221::-->
+<P>
+
+<CODE>(require 'sierpinski)</CODE>
+<A NAME="IDX1358"></A>
+</P>
+<P>
+
+<A NAME="IDX1359"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>make-sierpinski-indexer</B> <I>max-coordinate</I>
+<DD>Returns a procedure (eg hash-function) of 2 numeric arguments which
+preserves <EM>nearness</EM> in its mapping from NxN to N.
+<P>
+
+<VAR>max-coordinate</VAR> is the maximum coordinate (a positive integer) of a
+population of points. The returned procedures is a function that takes
+the x and y coordinates of a point, (non-negative integers) and returns
+an integer corresponding to the relative position of that point along a
+Sierpinski curve. (You can think of this as computing a (pseudo-)
+inverse of the Sierpinski spacefilling curve.)
+</P>
+<P>
+
+Example use: Make an indexer (hash-function) for integer points lying in
+square of integer grid points [0,99]x[0,99]:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define space-key (make-sierpinski-indexer 100))
+</pre></td></tr></table>Now let's compute the index of some points:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(space-key 24 78) => 9206
+(space-key 23 80) => 9172
+</pre></td></tr></table><P>
+
+Note that locations (24, 78) and (23, 80) are near in index and
+therefore, because the Sierpinski spacefilling curve is continuous, we
+know they must also be near in the plane. Nearness in the plane does
+not, however, necessarily correspond to nearness in index, although it
+<EM>tends</EM> to be so.
+</P>
+<P>
+
+Example applications:
+<UL>
+
+<LI>
+Sort points by Sierpinski index to get heuristic solution to
+<EM>travelling salesman problem</EM>. For details of performance,
+see L. Platzman and J. Bartholdi, &quot;Spacefilling curves and the
+Euclidean travelling salesman problem&quot;, JACM 36(4):719--737
+(October 1989) and references therein.
+<P>
+
+</P>
+<LI>
+Use Sierpinski index as key by which to store 2-dimensional data
+in a 1-dimensional data structure (such as a table). Then
+locations that are near each other in 2-d space will tend to
+be near each other in 1-d data structure; and locations that
+are near in 1-d data structure will be near in 2-d space. This
+can significantly speed retrieval from secondary storage because
+contiguous regions in the plane will tend to correspond to
+contiguous regions in secondary storage. (This is a standard
+technique for managing CAD/CAM or geographic data.)
+<P>
+
+</UL>
+</DL>
+<P>
+
+<A NAME="Soundex"></A>
+<HR SIZE="6">
+<A NAME="SEC222"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC221"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC223"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC207"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.2.8 Soundex </H3>
+<!--docid::SEC222::-->
+<P>
+
+<CODE>(require 'soundex)</CODE>
+<A NAME="IDX1360"></A>
+</P>
+<P>
+
+<A NAME="IDX1361"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>soundex</B> <I>name</I>
+<DD>Computes the <EM>soundex</EM> hash of <VAR>name</VAR>. Returns a string of an
+initial letter and up to three digits between 0 and 6. Soundex
+supposedly has the property that names that sound similar in normal
+English pronunciation tend to map to the same key.
+<P>
+
+Soundex was a classic algorithm used for manual filing of personal
+records before the advent of computers. It performs adequately for
+English names but has trouble with other languages.
+</P>
+<P>
+
+See Knuth, Vol. 3 <CITE>Sorting and searching</CITE>, pp 391--2
+</P>
+<P>
+
+To manage unusual inputs, <CODE>soundex</CODE> omits all non-alphabetic
+characters. Consequently, in this implementation:
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(soundex &lt;string of blanks&gt;) => &quot;&quot;
+(soundex &quot;&quot;) => &quot;&quot;
+</pre></td></tr></table><P>
+
+Examples from Knuth:
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(map soundex '(&quot;Euler&quot; &quot;Gauss&quot; &quot;Hilbert&quot; &quot;Knuth&quot;
+ &quot;Lloyd&quot; &quot;Lukasiewicz&quot;))
+ => (&quot;E460&quot; &quot;G200&quot; &quot;H416&quot; &quot;K530&quot; &quot;L300&quot; &quot;L222&quot;)
+
+(map soundex '(&quot;Ellery&quot; &quot;Ghosh&quot; &quot;Heilbronn&quot; &quot;Kant&quot;
+ &quot;Ladd&quot; &quot;Lissajous&quot;))
+ => (&quot;E460&quot; &quot;G200&quot; &quot;H416&quot; &quot;K530&quot; &quot;L300&quot; &quot;L222&quot;)
+</pre></td></tr></table><P>
+
+Some cases in which the algorithm fails (Knuth):
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(map soundex '(&quot;Rogers&quot; &quot;Rodgers&quot;)) => (&quot;R262&quot; &quot;R326&quot;)
+
+(map soundex '(&quot;Sinclair&quot; &quot;St. Clair&quot;)) => (&quot;S524&quot; &quot;S324&quot;)
+
+(map soundex '(&quot;Tchebysheff&quot; &quot;Chebyshev&quot;)) => (&quot;T212&quot; &quot;C121&quot;)
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="String Search"></A>
+<HR SIZE="6">
+<A NAME="SEC223"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC222"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC224"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC207"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.2.9 String Search </H3>
+<!--docid::SEC223::-->
+<P>
+
+<CODE>(require 'string-search)</CODE>
+<A NAME="IDX1362"></A>
+</P>
+<P>
+
+<A NAME="IDX1363"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>string-index</B> <I>string char</I>
+<DD><A NAME="IDX1364"></A>
+<DT><U>Procedure:</U> <B>string-index-ci</B> <I>string char</I>
+<DD>Returns the index of the first occurence of <VAR>char</VAR> within
+<VAR>string</VAR>, or <CODE>#f</CODE> if the <VAR>string</VAR> does not contain a
+character <VAR>char</VAR>.
+</DL>
+<P>
+
+<A NAME="IDX1365"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>string-reverse-index</B> <I>string char</I>
+<DD><A NAME="IDX1366"></A>
+<DT><U>Procedure:</U> <B>string-reverse-index-ci</B> <I>string char</I>
+<DD>Returns the index of the last occurence of <VAR>char</VAR> within
+<VAR>string</VAR>, or <CODE>#f</CODE> if the <VAR>string</VAR> does not contain a
+character <VAR>char</VAR>.
+</DL>
+<P>
+
+<A NAME="IDX1367"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>substring?</B> <I>pattern string</I>
+<DD><A NAME="IDX1368"></A>
+<DT><U>Procedure:</U> <B>substring-ci?</B> <I>pattern string</I>
+<DD>Searches <VAR>string</VAR> to see if some substring of <VAR>string</VAR> is equal
+to <VAR>pattern</VAR>. <CODE>substring?</CODE> returns the index of the first
+character of the first substring of <VAR>string</VAR> that is equal to
+<VAR>pattern</VAR>; or <CODE>#f</CODE> if <VAR>string</VAR> does not contain
+<VAR>pattern</VAR>.
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(substring? &quot;rat&quot; &quot;pirate&quot;) => 2
+(substring? &quot;rat&quot; &quot;outrage&quot;) => #f
+(substring? &quot;&quot; any-string) => 0
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1369"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>find-string-from-port?</B> <I>str in-port max-no-chars</I>
+<DD>Looks for a string <VAR>str</VAR> within the first <VAR>max-no-chars</VAR> chars
+of the input port <VAR>in-port</VAR>.
+<P>
+
+<A NAME="IDX1370"></A>
+<DT><U>Procedure:</U> <B>find-string-from-port?</B> <I>str in-port</I>
+<DD>When called with two arguments, the search span is limited by the end of
+the input stream.
+</P>
+<P>
+
+<A NAME="IDX1371"></A>
+<DT><U>Procedure:</U> <B>find-string-from-port?</B> <I>str in-port char</I>
+<DD>Searches up to the first occurrence of character <VAR>char</VAR> in
+<VAR>str</VAR>.
+</P>
+<P>
+
+<A NAME="IDX1372"></A>
+<DT><U>Procedure:</U> <B>find-string-from-port?</B> <I>str in-port proc</I>
+<DD>Searches up to the first occurrence of the procedure <VAR>proc</VAR>
+returning non-false when called with a character (from <VAR>in-port</VAR>)
+argument.
+</P>
+<P>
+
+When the <VAR>str</VAR> is found, <CODE>find-string-from-port?</CODE> returns the
+number of characters it has read from the port, and the port is set to
+read the first char after that (that is, after the <VAR>str</VAR>) The
+function returns <CODE>#f</CODE> when the <VAR>str</VAR> isn't found.
+</P>
+<P>
+
+<CODE>find-string-from-port?</CODE> reads the port <EM>strictly</EM>
+sequentially, and does not perform any buffering. So
+<CODE>find-string-from-port?</CODE> can be used even if the <VAR>in-port</VAR> is
+open to a pipe or other communication channel.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1373"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>string-subst</B> <I>txt old1 new1 <small>...</small></I>
+<DD>Returns a copy of string <VAR>txt</VAR> with all occurrences of string
+<VAR>old1</VAR> in <VAR>txt</VAR> replaced with <VAR>new1</VAR>; then <VAR>old2</VAR>
+replaced with <VAR>new2</VAR> <small>...</small>. Matches are found from the left.
+Matches do not overlap.
+</DL>
+<P>
+
+<A NAME="IDX1374"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>count-newlines</B> <I>str</I>
+<DD>Returns the number of `<SAMP>#\newline</SAMP>' characters in string <VAR>str</VAR>.
+</DL>
+<P>
+
+<A NAME="Sequence Comparison"></A>
+<HR SIZE="6">
+<A NAME="SEC224"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC223"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC225"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC207"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.2.10 Sequence Comparison </H3>
+<!--docid::SEC224::-->
+<P>
+
+<CODE>(require 'diff)</CODE>
+<A NAME="IDX1375"></A>
+<A NAME="IDX1376"></A>
+</P>
+<P>
+
+<CODE>diff:edit-length</CODE> implements the algorithm:
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>S. Wu, E. Myers, U. Manber, and W. Miller,
+ &quot;An O(NP) Sequence Comparison Algorithm,&quot;
+ Information Processing Letters 35, 6 (1990), 317-323.
+ <A HREF="http://www.cs.arizona.edu/people/gene/vita.html">http://www.cs.arizona.edu/people/gene/vita.html</A>
+</pre></td></tr></table>S. Wu, &lt;A HREF=&quot;http://www.cs.arizona.edu/people/gene/vita.html&quot;&gt;
+E. Myers,&lt;/A&gt; U. Manber, and W. Miller,
+&lt;A HREF=&quot;http://www.cs.arizona.edu/people/gene/PAPERS/np_diff.ps&quot;&gt;
+&quot;An O(NP) Sequence Comparison Algorithm,&quot;&lt;/A&gt;
+Information Processing Letters 35, 6 (1990), 317-323.
+<P>
+
+The values returned by <CODE>diff:edit-length</CODE> can be used to gauge
+the degree of match between two sequences.
+</P>
+<P>
+
+Surprisingly, &quot;An O(NP) Sequence Comparison Algorithm&quot; does not
+derive the edit sequence; only the sequence length. Developing this
+linear-space sub-quadratic-time algorithm for computing the edit
+sequence required hundreds of hours of work. I have submitted a
+paper describing the algorithm to the Journal of Computational
+Biology.
+</P>
+<P>
+
+If the items being sequenced are text lines, then the computed
+edit-list is equivalent to the output of the <EM>diff</EM> utility
+<A NAME="IDX1377"></A>
+program. If the items being sequenced are words, then it is like the
+lesser known <EM>spiff</EM> program.
+<A NAME="IDX1378"></A>
+</P>
+<P>
+
+<A NAME="IDX1379"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>diff:longest-common-subsequence</B> <I>array1 array2 =? p-lim</I>
+<DD><P>
+
+<A NAME="IDX1380"></A>
+<DT><U>Function:</U> <B>diff:longest-common-subsequence</B> <I>array1 array2 =?</I>
+<DD><VAR>array1</VAR> and <VAR>array2</VAR> are one-dimensional arrays. The procedure <VAR>=?</VAR> is used
+to compare sequence tokens for equality.
+</P>
+<P>
+
+The non-negative integer <VAR>p-lim</VAR>, if provided, is maximum number of
+deletions of the shorter sequence to allow. <CODE>diff:longest-common-subsequence</CODE> will return <CODE>#f</CODE>
+if more deletions would be necessary.
+</P>
+<P>
+
+<CODE>diff:longest-common-subsequence</CODE> returns a one-dimensional array of length <CODE>(quotient (- (+
+len1 len2) (diff:edit-length <VAR>array1</VAR> <VAR>array2</VAR>)) 2)</CODE> holding the longest sequence
+common to both <VAR>array</VAR>s.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1381"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>diff:edits</B> <I>array1 array2 =? p-lim</I>
+<DD><P>
+
+<A NAME="IDX1382"></A>
+<DT><U>Function:</U> <B>diff:edits</B> <I>array1 array2 =?</I>
+<DD><VAR>array1</VAR> and <VAR>array2</VAR> are one-dimensional arrays. The procedure <VAR>=?</VAR> is used
+to compare sequence tokens for equality.
+</P>
+<P>
+
+The non-negative integer <VAR>p-lim</VAR>, if provided, is maximum number of
+deletions of the shorter sequence to allow. <CODE>diff:edits</CODE> will return <CODE>#f</CODE>
+if more deletions would be necessary.
+</P>
+<P>
+
+<CODE>diff:edits</CODE> returns a vector of length <CODE>(diff:edit-length <VAR>array1</VAR> <VAR>array2</VAR>)</CODE> composed
+of a shortest sequence of edits transformaing <VAR>array1</VAR> to <VAR>array2</VAR>.
+</P>
+<P>
+
+Each edit is an integer:
+</P>
+<DL COMPACT>
+<DT><VAR>k</VAR> &gt; 0
+<DD>Inserts <CODE>(array-ref <VAR>array1</VAR> (+ -1 <VAR>j</VAR>))</CODE> into the sequence.
+<DT><VAR>k</VAR> &lt; 0
+<DD>Deletes <CODE>(array-ref <VAR>array2</VAR> (- -1 <VAR>k</VAR>))</CODE> from the sequence.
+</DL>
+</DL>
+<P>
+
+<A NAME="IDX1383"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>diff:edit-length</B> <I>array1 array2 =? p-lim</I>
+<DD><P>
+
+<A NAME="IDX1384"></A>
+<DT><U>Function:</U> <B>diff:edit-length</B> <I>array1 array2 =?</I>
+<DD><VAR>array1</VAR> and <VAR>array2</VAR> are one-dimensional arrays. The procedure <VAR>=?</VAR> is used
+to compare sequence tokens for equality.
+</P>
+<P>
+
+The non-negative integer <VAR>p-lim</VAR>, if provided, is maximum number of
+deletions of the shorter sequence to allow. <CODE>diff:edit-length</CODE> will return <CODE>#f</CODE>
+if more deletions would be necessary.
+</P>
+<P>
+
+<CODE>diff:edit-length</CODE> returns the length of the shortest sequence of edits transformaing
+<VAR>array1</VAR> to <VAR>array2</VAR>.
+</P>
+</DL>
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(diff:longest-common-subsequence &quot;fghiejcklm&quot; &quot;fgehijkpqrlm&quot; eqv?)
+=> &quot;fghijklm&quot;
+
+(diff:edit-length &quot;fghiejcklm&quot; &quot;fgehijkpqrlm&quot; eqv?)
+=> 6
+
+(diff:edits &quot;fghiejcklm&quot; &quot;fgehijkpqrlm&quot; eqv?)
+=> #As32(3 -5 -7 8 9 10)
+ ; e c h p q r
+</pre></td></tr></table><P>
+
+<A NAME="Procedures"></A>
+<HR SIZE="6">
+<A NAME="SEC225"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC224"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC226"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H2> 7.3 Procedures </H2>
+<!--docid::SEC225::-->
+<P>
+
+Anything that doesn't fall neatly into any of the other categories winds
+up here.
+</P>
+<P>
+
+<TABLE BORDER="0" CELLSPACING="0">
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC226">7.3.1 Type Coercion</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'coerce</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC227">7.3.2 String-Case</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'string-case</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC228">7.3.3 String Ports</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'string-port</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC229">7.3.4 Line I/O</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'line-i/o</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC230">7.3.5 Multi-Processing</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'process</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC231">7.3.6 Metric Units</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Portable manifest types for numeric values.</TD></TR>
+</TABLE>
+<P>
+
+<A NAME="Type Coercion"></A>
+<HR SIZE="6">
+<A NAME="SEC226"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC225"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC227"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC225"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.3.1 Type Coercion </H3>
+<!--docid::SEC226::-->
+<CODE>(require 'coerce)</CODE>
+<A NAME="IDX1385"></A>
+<P>
+
+<A NAME="IDX1386"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>type-of</B> <I>obj</I>
+<DD><P>
+
+Returns a symbol name for the type of <VAR>obj</VAR>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1387"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>coerce</B> <I>obj result-type</I>
+<DD><P>
+
+Converts and returns <VAR>obj</VAR> of type <CODE>char</CODE>, <CODE>number</CODE>,
+<CODE>string</CODE>, <CODE>symbol</CODE>, <CODE>list</CODE>, or <CODE>vector</CODE> to
+<VAR>result-type</VAR> (which must be one of these symbols).
+</P>
+</DL>
+<P>
+
+<A NAME="String-Case"></A>
+<HR SIZE="6">
+<A NAME="SEC227"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC226"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC228"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC225"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.3.2 String-Case </H3>
+<!--docid::SEC227::-->
+<P>
+
+<CODE>(require 'string-case)</CODE>
+<A NAME="IDX1388"></A>
+</P>
+<P>
+
+<A NAME="IDX1389"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>string-upcase</B> <I>str</I>
+<DD><A NAME="IDX1390"></A>
+<DT><U>Procedure:</U> <B>string-downcase</B> <I>str</I>
+<DD><A NAME="IDX1391"></A>
+<DT><U>Procedure:</U> <B>string-capitalize</B> <I>str</I>
+<DD>The obvious string conversion routines. These are non-destructive.
+</DL>
+<P>
+
+<A NAME="IDX1392"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>string-upcase!</B> <I>str</I>
+<DD><A NAME="IDX1393"></A>
+<DT><U>Function:</U> <B>string-downcase!</B> <I>str</I>
+<DD><A NAME="IDX1394"></A>
+<DT><U>Function:</U> <B>string-capitalize!</B> <I>str</I>
+<DD>The destructive versions of the functions above.
+</DL>
+<P>
+
+<A NAME="IDX1395"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>string-ci-&gt;symbol</B> <I>str</I>
+<DD>Converts string <VAR>str</VAR> to a symbol having the same case as if the
+symbol had been <CODE>read</CODE>.
+</DL>
+<P>
+
+<A NAME="IDX1396"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>symbol-append</B> <I>obj1 <small>...</small></I>
+<DD>Converts <VAR>obj1</VAR> <small>...</small> to strings, appends them, and converts to a
+symbol which is returned. Strings and numbers are converted to read's
+symbol case; the case of symbol characters is not changed. #f is
+converted to the empty string (symbol).
+</DL>
+<P>
+
+<A NAME="IDX1397"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>StudlyCapsExpand</B> <I>str delimiter</I>
+<DD><A NAME="IDX1398"></A>
+<DT><U>Function:</U> <B>StudlyCapsExpand</B> <I>str</I>
+<DD><VAR>delimiter</VAR> must be a string or character. If absent,
+<VAR>delimiter</VAR> defaults to `<SAMP>-</SAMP>'. <CODE>StudlyCapsExpand</CODE> returns a
+copy of <VAR>str</VAR> where <VAR>delimiter</VAR> is inserted between each
+lower-case character immediately followed by an upper-case character;
+and between two upper-case characters immediately followed by a
+lower-case character.
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(StudlyCapsExpand &quot;aX&quot; &quot; &quot;) => &quot;a X&quot;
+(StudlyCapsExpand &quot;aX&quot; &quot;..&quot;) => &quot;a..X&quot;
+(StudlyCapsExpand &quot;AX&quot;) => &quot;AX&quot;
+(StudlyCapsExpand &quot;Ax&quot;) => &quot;Ax&quot;
+(StudlyCapsExpand &quot;AXLE&quot;) => &quot;AXLE&quot;
+(StudlyCapsExpand &quot;aAXACz&quot;) => &quot;a-AXA-Cz&quot;
+(StudlyCapsExpand &quot;AaXACz&quot;) => &quot;Aa-XA-Cz&quot;
+(StudlyCapsExpand &quot;AAaXACz&quot;) => &quot;A-Aa-XA-Cz&quot;
+(StudlyCapsExpand &quot;AAaXAC&quot;) => &quot;A-Aa-XAC&quot;
+</pre></td></tr></table><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="String Ports"></A>
+<HR SIZE="6">
+<A NAME="SEC228"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC227"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC229"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC225"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.3.3 String Ports </H3>
+<!--docid::SEC228::-->
+<P>
+
+<CODE>(require 'string-port)</CODE>
+<A NAME="IDX1399"></A>
+</P>
+<P>
+
+<A NAME="IDX1400"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>call-with-output-string</B> <I>proc</I>
+<DD><VAR>proc</VAR> must be a procedure of one argument. This procedure calls
+<VAR>proc</VAR> with one argument: a (newly created) output port. When the
+function returns, the string composed of the characters written into the
+port is returned.
+</DL>
+<P>
+
+<A NAME="IDX1401"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>call-with-input-string</B> <I>string proc</I>
+<DD><VAR>proc</VAR> must be a procedure of one argument. This procedure calls
+<VAR>proc</VAR> with one argument: an (newly created) input port from which
+<VAR>string</VAR>'s contents may be read. When <VAR>proc</VAR> returns, the port
+is closed and the value yielded by the procedure <VAR>proc</VAR> is
+returned.
+</DL>
+<P>
+
+<A NAME="Line I/O"></A>
+<HR SIZE="6">
+<A NAME="SEC229"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC228"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC230"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC225"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.3.4 Line I/O </H3>
+<!--docid::SEC229::-->
+<P>
+
+<CODE>(require 'line-i/o)</CODE>
+<A NAME="IDX1402"></A>
+</P>
+<P>
+
+<A NAME="IDX1403"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>read-line</B>
+<DD><P>
+
+<A NAME="IDX1404"></A>
+<DT><U>Function:</U> <B>read-line</B> <I>port</I>
+<DD>Returns a string of the characters up to, but not including a
+newline or end of file, updating <VAR>port</VAR> to point to the
+character following the newline. If no characters are available, an
+end of file object is returned. The <VAR>port</VAR> argument may be
+omitted, in which case it defaults to the value returned by
+<CODE>current-input-port</CODE>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1405"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>read-line!</B> <I>string</I>
+<DD><P>
+
+<A NAME="IDX1406"></A>
+<DT><U>Procedure:</U> <B>read-line!</B> <I>string port</I>
+<DD>Fills <VAR>string</VAR> with characters up to, but not including a newline or end
+of file, updating the <VAR>port</VAR> to point to the last character read
+or following the newline if it was read. If no characters are
+available, an end of file object is returned. If a newline or end
+of file was found, the number of characters read is returned.
+Otherwise, <CODE>#f</CODE> is returned. The <VAR>port</VAR> argument may be
+omitted, in which case it defaults to the value returned by
+<CODE>current-input-port</CODE>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1407"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>write-line</B> <I>string</I>
+<DD><P>
+
+<A NAME="IDX1408"></A>
+<DT><U>Function:</U> <B>write-line</B> <I>string port</I>
+<DD>Writes <VAR>string</VAR> followed by a newline to the given <VAR>port</VAR> and returns
+an unspecified value. The <VAR>Port</VAR> argument may be omitted, in
+which case it defaults to the value returned by
+<CODE>current-input-port</CODE>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1409"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>system-&gt;line</B> <I>command tmp</I>
+<DD><P>
+
+<A NAME="IDX1410"></A>
+<DT><U>Function:</U> <B>system-&gt;line</B> <I>command</I>
+<DD><VAR>command</VAR> must be a string. The string <VAR>tmp</VAR>, if supplied, is a path to use as
+a temporary file. <CODE>system-&gt;line</CODE> calls <CODE>system</CODE> with <VAR>command</VAR> as argument,
+redirecting stdout to file <VAR>tmp</VAR>. <CODE>system-&gt;line</CODE> returns a string containing the
+first line of output from <VAR>tmp</VAR>.
+</P>
+</DL>
+<P>
+
+<A NAME="Multi-Processing"></A>
+<HR SIZE="6">
+<A NAME="SEC230"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC229"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC231"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC225"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.3.5 Multi-Processing </H3>
+<!--docid::SEC230::-->
+<P>
+
+<CODE>(require 'process)</CODE>
+<A NAME="IDX1411"></A>
+</P>
+<P>
+
+This module implements asynchronous (non-polled) time-sliced
+multi-processing in the SCM Scheme implementation using procedures
+<CODE>alarm</CODE> and <CODE>alarm-interrupt</CODE>.
+<A NAME="IDX1412"></A>
+<A NAME="IDX1413"></A>
+Until this is ported to another implementation, consider it an example
+of writing schedulers in Scheme.
+</P>
+<P>
+
+<A NAME="IDX1414"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>add-process!</B> <I>proc</I>
+<DD>Adds proc, which must be a procedure (or continuation) capable of
+accepting accepting one argument, to the <CODE>process:queue</CODE>. The
+value returned is unspecified. The argument to <VAR>proc</VAR> should be
+ignored. If <VAR>proc</VAR> returns, the process is killed.
+</DL>
+<P>
+
+<A NAME="IDX1415"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>process:schedule!</B>
+<DD>Saves the current process on <CODE>process:queue</CODE> and runs the next
+process from <CODE>process:queue</CODE>. The value returned is
+unspecified.
+</DL>
+<P>
+
+<A NAME="IDX1416"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>kill-process!</B>
+<DD>Kills the current process and runs the next process from
+<CODE>process:queue</CODE>. If there are no more processes on
+<CODE>process:queue</CODE>, <CODE>(slib:exit)</CODE> is called (see section <A HREF="slib_2.html#SEC17">2.4 System</A>).
+</DL>
+<P>
+
+<A NAME="Metric Units"></A>
+<HR SIZE="6">
+<A NAME="SEC231"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC230"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC232"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC225"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.3.6 Metric Units </H3>
+<!--docid::SEC231::-->
+<P>
+
+<CODE>(require 'metric-units)</CODE>
+<A NAME="IDX1417"></A>
+</P>
+<P>
+
+<A HREF="http://swissnet.ai.mit.edu/~jaffer/MIXF.html">http://swissnet.ai.mit.edu/~jaffer/MIXF.html</A>
+</P>
+<P>
+
+<EM>Metric Interchange Format</EM> is a character string encoding for
+numerical values and units which:
+</P>
+<P>
+
+<UL>
+<LI>
+is unambiguous in all locales;
+<P>
+
+</P>
+<LI>
+uses only [TOG] &quot;Portable Character Set&quot; characters matching &quot;Basic
+Latin&quot; characters in Plane 0 of the Universal Character Set [UCS];
+<P>
+
+</P>
+<LI>
+is transparent to [UTF-7] and [UTF-8] UCS transformation formats;
+<P>
+
+</P>
+<LI>
+is human readable and writable;
+<P>
+
+</P>
+<LI>
+is machine readable and writable;
+<P>
+
+</P>
+<LI>
+incorporates SI prefixes and units;
+<P>
+
+</P>
+<LI>
+incorporates [ISO 6093] numbers; and
+<P>
+
+</P>
+<LI>
+incorporates [IEC 60027-2] binary prefixes.
+</UL>
+<P>
+
+In the expression for the value of a quantity, the unit symbol is placed
+after the numerical value. A dot (PERIOD, `<SAMP>.</SAMP>') is placed between
+the numerical value and the unit symbol.
+</P>
+<P>
+
+Within a compound unit, each of the base and derived symbols can
+optionally have an attached SI prefix.
+</P>
+<P>
+
+Unit symbols formed from other unit symbols by multiplication are
+indicated by means of a dot (PERIOD, `<SAMP>.</SAMP>') placed between them.
+</P>
+<P>
+
+Unit symbols formed from other unit symbols by division are indicated by
+means of a SOLIDUS (`<SAMP>/</SAMP>') or negative exponents. The SOLIDUS must
+not be repeated in the same compound unit unless contained within a
+parenthesized subexpression.
+</P>
+<P>
+
+The grouping formed by a prefix symbol attached to a unit symbol
+constitutes a new inseparable symbol (forming a multiple or submultiple
+of the unit concerned) which can be raised to a positive or negative
+power and which can be combined with other unit symbols to form compound
+unit symbols.
+</P>
+<P>
+
+The grouping formed by surrounding compound unit symbols with
+parentheses (`<SAMP>(</SAMP>' and `<SAMP>)</SAMP>') constitutes a new inseparable symbol
+which can be raised to a positive or negative power and which can be
+combined with other unit symbols to form compound unit symbols.
+</P>
+<P>
+
+Compound prefix symbols, that is, prefix symbols formed by the
+juxtaposition of two or more prefix symbols, are not permitted.
+</P>
+<P>
+
+Prefix symbols are not used with the time-related unit symbols min
+(minute), h (hour), d (day). No prefix symbol may be used with dB
+(decibel). Only submultiple prefix symbols may be used with the unit
+symbols L (liter), Np (neper), o (degree), oC (degree Celsius), rad
+(radian), and sr (steradian). Submultiple prefix symbols may not be
+used with the unit symbols t (metric ton), r (revolution), or Bd (baud).
+</P>
+<P>
+
+A unit exponent follows the unit, separated by a CIRCUMFLEX (`<SAMP>^</SAMP>').
+Exponents may be positive or negative. Fractional exponents must be
+parenthesized.
+</P>
+<P>
+
+<HR SIZE="6">
+<A NAME="SEC232"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC231"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC233"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC225"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H4> 7.3.6.1 SI Prefixes </H4>
+<!--docid::SEC232::-->
+<TABLE><tr><td>&nbsp;</td><td class=example><pre> Factor Name Symbol | Factor Name Symbol
+ ====== ==== ====== | ====== ==== ======
+ 1e24 yotta Y | 1e-1 deci d
+ 1e21 zetta Z | 1e-2 centi c
+ 1e18 exa E | 1e-3 milli m
+ 1e15 peta P | 1e-6 micro u
+ 1e12 tera T | 1e-9 nano n
+ 1e9 giga G | 1e-12 pico p
+ 1e6 mega M | 1e-15 femto f
+ 1e3 kilo k | 1e-18 atto a
+ 1e2 hecto h | 1e-21 zepto z
+ 1e1 deka da | 1e-24 yocto y
+</pre></td></tr></table><P>
+
+<HR SIZE="6">
+<A NAME="SEC233"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC232"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC234"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC225"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H4> 7.3.6.2 Binary Prefixes </H4>
+<!--docid::SEC233::-->
+<P>
+
+These binary prefixes are valid only with the units B (byte) and bit.
+However, decimal prefixes can also be used with bit; and decimal
+multiple (not submultiple) prefixes can also be used with B (byte).
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre> Factor (power-of-2) Name Symbol
+ ====== ============ ==== ======
+ 1.152921504606846976e18 (2^60) exbi Ei
+ 1.125899906842624e15 (2^50) pebi Pi
+ 1.099511627776e12 (2^40) tebi Ti
+ 1.073741824e9 (2^30) gibi Gi
+ 1.048576e6 (2^20) mebi Mi
+ 1.024e3 (2^10) kibi Ki
+</pre></td></tr></table><P>
+
+<HR SIZE="6">
+<A NAME="SEC234"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC233"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC235"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC225"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H4> 7.3.6.3 Unit Symbols </H4>
+<!--docid::SEC234::-->
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre> Type of Quantity Name Symbol Equivalent
+ ================ ==== ====== ==========
+time second s
+time minute min = 60.s
+time hour h = 60.min
+time day d = 24.h
+frequency hertz Hz s^-1
+signaling rate baud Bd s^-1
+length meter m
+volume liter L dm^3
+plane angle radian rad
+solid angle steradian sr rad^2
+plane angle revolution * r = 6.283185307179586.rad
+plane angle degree * o = 2.777777777777778e-3.r
+information capacity bit bit
+information capacity byte, octet B = 8.bit
+mass gram g
+mass ton t Mg
+mass unified atomic mass unit u = 1.66053873e-27.kg
+amount of substance mole mol
+catalytic activity katal kat mol/s
+thermodynamic temperature kelvin K
+centigrade temperature degree Celsius oC
+luminous intensity candela cd
+luminous flux lumen lm cd.sr
+illuminance lux lx lm/m^2
+force newton N m.kg.s^-2
+pressure, stress pascal Pa N/m^2
+energy, work, heat joule J N.m
+energy electronvolt eV = 1.602176462e-19.J
+power, radiant flux watt W J/s
+logarithm of power ratio neper Np
+logarithm of power ratio decibel * dB = 0.1151293.Np
+electric current ampere A
+electric charge coulomb C s.A
+electric potential, EMF volt V W/A
+capacitance farad F C/V
+electric resistance ohm Ohm V/A
+electric conductance siemens S A/V
+magnetic flux weber Wb V.s
+magnetic flux density tesla T Wb/m^2
+inductance henry H Wb/A
+radionuclide activity becquerel Bq s^-1
+absorbed dose energy gray Gy m^2.s^-2
+dose equivalent sievert Sv m^2.s^-2
+</pre></td></tr></table><P>
+
+* The formulas are:
+</P>
+<P>
+
+<UL>
+<LI>
+r/rad = 8 * atan(1)
+<LI>
+o/r = 1 / 360
+<LI>
+db/Np = ln(10) / 20
+</UL>
+<P>
+
+<A NAME="IDX1418"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>si:conversion-factor</B> <I>to-unit from-unit</I>
+<DD>If the strings <VAR>from-unit</VAR> and <VAR>to-unit</VAR> express valid unit
+expressions for quantities of the same unit-dimensions, then the value
+returned by <CODE>si:conversion-factor</CODE> will be such that multiplying a
+numerical value expressed in <VAR>from-unit</VAR>s by the returned conversion
+factor yields the numerical value expressed in <VAR>to-unit</VAR>s.
+<P>
+
+Otherwise, <CODE>si:conversion-factor</CODE> returns:
+</P>
+<P>
+
+</P>
+<DL COMPACT>
+<DT>-3
+<DD>if neither <VAR>from-unit</VAR> nor <VAR>to-unit</VAR> is a syntactically valid
+unit.
+<DT>-2
+<DD>if <VAR>from-unit</VAR> is not a syntactically valid unit.
+<DT>-1
+<DD>if <VAR>to-unit</VAR> is not a syntactically valid unit.
+<DT>0
+<DD>if linear conversion (by a factor) is not possible.
+</DL>
+<P>
+
+</P>
+</DL>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(si:conversion-factor &quot;km/s&quot; &quot;m/s&quot; ) => 0.001
+(si:conversion-factor &quot;N&quot; &quot;m/s&quot; ) => 0
+(si:conversion-factor &quot;moC&quot; &quot;oC&quot; ) => 1000
+(si:conversion-factor &quot;mK&quot; &quot;oC&quot; ) => 0
+(si:conversion-factor &quot;rad&quot; &quot;o&quot; ) => 0.0174533
+(si:conversion-factor &quot;K&quot; &quot;o&quot; ) => 0
+(si:conversion-factor &quot;K&quot; &quot;K&quot; ) => 1
+(si:conversion-factor &quot;oK&quot; &quot;oK&quot; ) => -3
+(si:conversion-factor &quot;&quot; &quot;s/s&quot; ) => 1
+(si:conversion-factor &quot;km/h&quot; &quot;mph&quot; ) => -2
+</pre></td></tr></table><P>
+
+<A NAME="Standards Support"></A>
+<HR SIZE="6">
+<A NAME="SEC235"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC234"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC236"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H2> 7.4 Standards Support </H2>
+<!--docid::SEC235::-->
+<P>
+
+<TABLE BORDER="0" CELLSPACING="0">
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC236">7.4.1 RnRS</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Revised Reports on Scheme</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC237">7.4.2 With-File</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'with-file</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC238">7.4.3 Transcripts</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'transcript</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC239">7.4.4 Rev2 Procedures</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'rev2-procedures</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC240">7.4.5 Rev4 Optional Procedures</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'rev4-optional-procedures</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC241">7.4.6 Multi-argument / and -</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'multiarg/and-</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC242">7.4.7 Multi-argument Apply</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'multiarg-apply</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC243">7.4.8 Rationalize</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'rationalize</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC244">7.4.9 Promises</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'delay</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC245">7.4.10 Dynamic-Wind</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'dynamic-wind</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC246">7.4.11 Eval</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'eval</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC247">7.4.12 Values</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'values</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC248">7.4.13 SRFI</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'http://srfi.schemers.org/srfi-0/srfi-0.html</TD></TR>
+</TABLE>
+<P>
+
+<A NAME="RnRS"></A>
+<HR SIZE="6">
+<A NAME="SEC236"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC235"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC237"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC235"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.4.1 RnRS </H3>
+<!--docid::SEC236::-->
+<P>
+
+The <CODE>r2rs</CODE>, <CODE>r3rs</CODE>, <CODE>r4rs</CODE>, and <CODE>r5rs</CODE> features
+attempt to provide procedures and macros to bring a Scheme
+implementation to the desired version of Scheme.
+</P>
+<P>
+
+<A NAME="IDX1419"></A>
+</P>
+<DL>
+<DT><U>Feature:</U> <B>r2rs</B>
+<DD><A NAME="IDX1420"></A>
+Requires features implementing procedures and optional procedures
+specified by <CITE>Revised^2 Report on the Algorithmic Language Scheme</CITE>;
+namely <CODE>rev3-procedures</CODE> and <CODE>rev2-procedures</CODE>.
+</DL>
+<P>
+
+<A NAME="IDX1421"></A>
+</P>
+<DL>
+<DT><U>Feature:</U> <B>r3rs</B>
+<DD><A NAME="IDX1422"></A>
+Requires features implementing procedures and optional procedures
+specified by <CITE>Revised^3 Report on the Algorithmic Language Scheme</CITE>;
+namely <CODE>rev3-procedures</CODE>.
+<P>
+
+<EM>Note:</EM> SLIB already mandates the <CODE>r3rs</CODE> procedures which can
+be portably implemented in <CODE>r4rs</CODE> implementations.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1423"></A>
+</P>
+<DL>
+<DT><U>Feature:</U> <B>r4rs</B>
+<DD><A NAME="IDX1424"></A>
+Requires features implementing procedures and optional procedures
+specified by <CITE>Revised^4 Report on the Algorithmic Language Scheme</CITE>;
+namely <CODE>rev4-optional-procedures</CODE>.
+</DL>
+<P>
+
+<A NAME="IDX1425"></A>
+</P>
+<DL>
+<DT><U>Feature:</U> <B>r5rs</B>
+<DD><A NAME="IDX1426"></A>
+Requires features implementing procedures and optional procedures
+specified by <CITE>Revised^5 Report on the Algorithmic Language Scheme</CITE>;
+namely <CODE>values</CODE>, <CODE>macro</CODE>, and <CODE>eval</CODE>.
+</DL>
+<P>
+
+<A NAME="With-File"></A>
+<HR SIZE="6">
+<A NAME="SEC237"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC236"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC238"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC235"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.4.2 With-File </H3>
+<!--docid::SEC237::-->
+<P>
+
+<CODE>(require 'with-file)</CODE>
+<A NAME="IDX1427"></A>
+</P>
+<P>
+
+<A NAME="IDX1428"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>with-input-from-file</B> <I>file thunk</I>
+<DD><A NAME="IDX1429"></A>
+<DT><U>Function:</U> <B>with-output-to-file</B> <I>file thunk</I>
+<DD>Description found in R4RS.
+</DL>
+<P>
+
+<A NAME="Transcripts"></A>
+<HR SIZE="6">
+<A NAME="SEC238"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC237"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC239"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC235"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.4.3 Transcripts </H3>
+<!--docid::SEC238::-->
+<P>
+
+<CODE>(require 'transcript)</CODE>
+<A NAME="IDX1430"></A>
+</P>
+<P>
+
+<A NAME="IDX1431"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>transcript-on</B> <I>filename</I>
+<DD><A NAME="IDX1432"></A>
+<DT><U>Function:</U> <B>transcript-off</B> <I>filename</I>
+<DD>Redefines <CODE>read-char</CODE>, <CODE>read</CODE>, <CODE>write-char</CODE>,
+<CODE>write</CODE>, <CODE>display</CODE>, and <CODE>newline</CODE>.
+</DL>
+<P>
+
+<A NAME="Rev2 Procedures"></A>
+<HR SIZE="6">
+<A NAME="SEC239"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC238"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC240"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC235"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.4.4 Rev2 Procedures </H3>
+<!--docid::SEC239::-->
+<P>
+
+<CODE>(require 'rev2-procedures)</CODE>
+<A NAME="IDX1433"></A>
+</P>
+<P>
+
+The procedures below were specified in the <CITE>Revised^2 Report on
+Scheme</CITE>. <STRONG>N.B.</STRONG>: The symbols <CODE>1+</CODE> and <CODE>-1+</CODE> are not
+<CITE>R4RS</CITE> syntax. Scheme-&gt;C, for instance, chokes on this
+module.
+</P>
+<P>
+
+<A NAME="IDX1434"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>substring-move-left!</B> <I>string1 start1 end1 string2 start2</I>
+<DD><A NAME="IDX1435"></A>
+<DT><U>Procedure:</U> <B>substring-move-right!</B> <I>string1 start1 end1 string2 start2</I>
+<DD><VAR>string1</VAR> and <VAR>string2</VAR> must be a strings, and <VAR>start1</VAR>,
+<VAR>start2</VAR> and <VAR>end1</VAR> must be exact integers satisfying
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=display><pre style="font-family: serif">0 &lt;= <VAR>start1</VAR> &lt;= <VAR>end1</VAR> &lt;= (string-length <VAR>string1</VAR>)
+0 &lt;= <VAR>start2</VAR> &lt;= <VAR>end1</VAR> - <VAR>start1</VAR> + <VAR>start2</VAR> &lt;= (string-length <VAR>string2</VAR>)
+</pre></td></tr></table><P>
+
+<CODE>substring-move-left!</CODE> and <CODE>substring-move-right!</CODE> store
+characters of <VAR>string1</VAR> beginning with index <VAR>start1</VAR>
+(inclusive) and ending with index <VAR>end1</VAR> (exclusive) into
+<VAR>string2</VAR> beginning with index <VAR>start2</VAR> (inclusive).
+</P>
+<P>
+
+<CODE>substring-move-left!</CODE> stores characters in time order of
+increasing indices. <CODE>substring-move-right!</CODE> stores characters in
+time order of increasing indeces.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1436"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>substring-fill!</B> <I>string start end char</I>
+<DD>Fills the elements <VAR>start</VAR>--<VAR>end</VAR> of <VAR>string</VAR> with the
+character <VAR>char</VAR>.
+</DL>
+<P>
+
+<A NAME="IDX1437"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>string-null?</B> <I>str</I>
+<DD>== <CODE>(= 0 (string-length <VAR>str</VAR>))</CODE>
+</DL>
+<P>
+
+<A NAME="IDX1438"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>append!</B> <I>pair1 <small>...</small></I>
+<DD>Destructively appends its arguments. Equivalent to <CODE>nconc</CODE>.
+</DL>
+<P>
+
+<A NAME="IDX1439"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>1+</B> <I>n</I>
+<DD>Adds 1 to <VAR>n</VAR>.
+</DL>
+<P>
+
+<A NAME="IDX1440"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>-1+</B> <I>n</I>
+<DD>Subtracts 1 from <VAR>n</VAR>.
+</DL>
+<P>
+
+<A NAME="IDX1441"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>&lt;?</B>
+<DD><A NAME="IDX1442"></A>
+<DT><U>Function:</U> <B>&lt;=?</B>
+<DD><A NAME="IDX1443"></A>
+<DT><U>Function:</U> <B>=?</B>
+<DD><A NAME="IDX1444"></A>
+<DT><U>Function:</U> <B>&gt;?</B>
+<DD><A NAME="IDX1445"></A>
+<DT><U>Function:</U> <B>&gt;=?</B>
+<DD>These are equivalent to the procedures of the same name but without the
+trailing `<SAMP>?</SAMP>'.
+</DL>
+<P>
+
+<A NAME="Rev4 Optional Procedures"></A>
+<HR SIZE="6">
+<A NAME="SEC240"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC239"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC241"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC235"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.4.5 Rev4 Optional Procedures </H3>
+<!--docid::SEC240::-->
+<P>
+
+<CODE>(require 'rev4-optional-procedures)</CODE>
+<A NAME="IDX1446"></A>
+</P>
+<P>
+
+For the specification of these optional procedures,
+See section `Standard procedures' in <CITE>Revised(4) Scheme</CITE>.
+</P>
+<P>
+
+<A NAME="IDX1447"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>list-tail</B> <I>l p</I>
+<DD></DL>
+<P>
+
+<A NAME="IDX1448"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>string-&gt;list</B> <I>s</I>
+<DD></DL>
+<P>
+
+<A NAME="IDX1449"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>list-&gt;string</B> <I>l</I>
+<DD></DL>
+<P>
+
+<A NAME="IDX1450"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>string-copy</B>
+<DD></DL>
+<P>
+
+<A NAME="IDX1451"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>string-fill!</B> <I>s obj</I>
+<DD></DL>
+<P>
+
+<A NAME="IDX1452"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>list-&gt;vector</B> <I>l</I>
+<DD></DL>
+<P>
+
+<A NAME="IDX1453"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>vector-&gt;list</B> <I>s</I>
+<DD></DL>
+<P>
+
+<A NAME="IDX1454"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>vector-fill!</B> <I>s obj</I>
+<DD></DL>
+<P>
+
+<A NAME="Multi-argument / and -"></A>
+<HR SIZE="6">
+<A NAME="SEC241"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC240"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC242"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC235"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.4.6 Multi-argument / and - </H3>
+<!--docid::SEC241::-->
+<P>
+
+<CODE>(require 'multiarg/and-)</CODE>
+<A NAME="IDX1455"></A>
+</P>
+<P>
+
+For the specification of these optional forms, See section `Numerical operations' in <CITE>Revised(4) Scheme</CITE>.
+</P>
+<P>
+
+<A NAME="IDX1456"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>/</B> <I>dividend divisor1 <small>...</small></I>
+<DD></DL>
+<P>
+
+<A NAME="IDX1457"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>-</B> <I>minuend subtrahend1 <small>...</small></I>
+<DD></DL>
+<P>
+
+<A NAME="Multi-argument Apply"></A>
+<HR SIZE="6">
+<A NAME="SEC242"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC241"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC243"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC235"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.4.7 Multi-argument Apply </H3>
+<!--docid::SEC242::-->
+<P>
+
+<CODE>(require 'multiarg-apply)</CODE>
+<A NAME="IDX1458"></A>
+</P>
+<P>
+
+For the specification of this optional form,
+See section `Control features' in <CITE>Revised(4) Scheme</CITE>.
+</P>
+<P>
+
+<A NAME="IDX1459"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>apply</B> <I>proc arg1 <small>...</small></I>
+<DD></DL>
+<P>
+
+<A NAME="Rationalize"></A>
+<HR SIZE="6">
+<A NAME="SEC243"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC242"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC244"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC235"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.4.8 Rationalize </H3>
+<!--docid::SEC243::-->
+<P>
+
+<CODE>(require 'rationalize)</CODE>
+<A NAME="IDX1460"></A>
+</P>
+<P>
+
+<A NAME="IDX1461"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>rationalize</B> <I>x e</I>
+<DD><P>
+
+Computes the correct result for exact arguments (provided the
+implementation supports exact rational numbers of unlimited precision);
+and produces a reasonable answer for inexact arguments when inexact
+arithmetic is implemented using floating-point.
+</P>
+<P>
+
+</P>
+</DL>
+<CODE>Rationalize</CODE> has limited use in implementations lacking exact
+(non-integer) rational numbers. The following procedures return a list
+of the numerator and denominator.
+<P>
+
+<A NAME="IDX1462"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>find-ratio</B> <I>x e</I>
+<DD><P>
+
+<CODE>find-ratio</CODE> returns the list of the <EM>simplest</EM>
+numerator and denominator whose quotient differs from <VAR>x</VAR> by no more
+than <VAR>e</VAR>.
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=display><pre style="font-family: serif"><TT>(find-ratio 3/97 .0001) => (3 97)
+(find-ratio 3/97 .001) => (1 32)
+</TT>
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1463"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>find-ratio-between</B> <I>x y</I>
+<DD><P>
+
+<CODE>find-ratio-between</CODE> returns the list of the <EM>simplest</EM>
+numerator and denominator between <VAR>x</VAR> and <VAR>y</VAR>.
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=display><pre style="font-family: serif"><TT>(find-ratio-between 2/7 3/5) => (1 2)
+(find-ratio-between -3/5 -2/7) => (-1 2)
+</TT>
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="Promises"></A>
+<HR SIZE="6">
+<A NAME="SEC244"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC243"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC245"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC235"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.4.9 Promises </H3>
+<!--docid::SEC244::-->
+<P>
+
+<CODE>(require 'promise)</CODE>
+<A NAME="IDX1464"></A>
+</P>
+<P>
+
+<A NAME="IDX1465"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>make-promise</B> <I>proc</I>
+<DD></DL>
+<P>
+
+<A NAME="IDX1466"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>force</B> <I>promise</I>
+<DD></DL>
+<P>
+
+<CODE>(require 'delay)</CODE> provides <CODE>force</CODE> and <CODE>delay</CODE>:
+</P>
+<P>
+
+<A NAME="IDX1467"></A>
+</P>
+<DL>
+<DT><U>Macro:</U> <B>delay</B> <I>obj</I>
+<DD>Change occurrences of <CODE>(delay <VAR>expression</VAR>)</CODE> to
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(make-promise (lambda () <VAR>expression</VAR>))
+</pre></td></tr></table><P>
+
+</P>
+</DL>
+<P>
+
+(see section `Control features' in <CITE>Revised(4) Scheme</CITE>).
+</P>
+<P>
+
+<A NAME="Dynamic-Wind"></A>
+<HR SIZE="6">
+<A NAME="SEC245"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC244"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC246"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC235"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.4.10 Dynamic-Wind </H3>
+<!--docid::SEC245::-->
+<P>
+
+<CODE>(require 'dynamic-wind)</CODE>
+<A NAME="IDX1468"></A>
+</P>
+<P>
+
+This facility is a generalization of Common LISP <CODE>unwind-protect</CODE>,
+designed to take into account the fact that continuations produced by
+<CODE>call-with-current-continuation</CODE> may be reentered.
+</P>
+<P>
+
+<A NAME="IDX1469"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>dynamic-wind</B> <I>thunk1 thunk2 thunk3</I>
+<DD>The arguments <VAR>thunk1</VAR>, <VAR>thunk2</VAR>, and <VAR>thunk3</VAR> must all be
+procedures of no arguments (thunks).
+<P>
+
+<CODE>dynamic-wind</CODE> calls <VAR>thunk1</VAR>, <VAR>thunk2</VAR>, and then
+<VAR>thunk3</VAR>. The value returned by <VAR>thunk2</VAR> is returned as the
+result of <CODE>dynamic-wind</CODE>. <VAR>thunk3</VAR> is also called just before
+control leaves the dynamic context of <VAR>thunk2</VAR> by calling a
+continuation created outside that context. Furthermore, <VAR>thunk1</VAR> is
+called before reentering the dynamic context of <VAR>thunk2</VAR> by calling
+a continuation created inside that context. (Control is inside the
+context of <VAR>thunk2</VAR> if <VAR>thunk2</VAR> is on the current return stack).
+</P>
+<P>
+
+<STRONG>Warning:</STRONG> There is no provision for dealing with errors or
+interrupts. If an error or interrupt occurs while using
+<CODE>dynamic-wind</CODE>, the dynamic environment will be that in effect at
+the time of the error or interrupt.
+</P>
+</DL>
+<P>
+
+<A NAME="Eval"></A>
+<HR SIZE="6">
+<A NAME="SEC246"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC245"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC247"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC235"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.4.11 Eval </H3>
+<!--docid::SEC246::-->
+<P>
+
+<CODE>(require 'eval)</CODE>
+<A NAME="IDX1470"></A>
+</P>
+<P>
+
+<A NAME="IDX1471"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>eval</B> <I>expression environment-specifier</I>
+<DD><P>
+
+Evaluates <VAR>expression</VAR> in the specified environment and returns its
+value. <VAR>Expression</VAR> must be a valid Scheme expression represented
+as data, and <VAR>environment-specifier</VAR> must be a value returned by one
+of the three procedures described below. Implementations may extend
+<CODE>eval</CODE> to allow non-expression programs (definitions) as the first
+argument and to allow other values as environments, with the restriction
+that <CODE>eval</CODE> is not allowed to create new bindings in the
+environments associated with <CODE>null-environment</CODE> or
+<CODE>scheme-report-environment</CODE>.
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(eval '(* 7 3) (scheme-report-environment 5))
+ => 21
+
+(let ((f (eval '(lambda (f x) (f x x))
+ (null-environment))))
+ (f + 10))
+ => 20
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1472"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>scheme-report-environment</B> <I>version</I>
+<DD><A NAME="IDX1473"></A>
+<DT><U>Function:</U> <B>null-environment</B> <I>version</I>
+<DD><A NAME="IDX1474"></A>
+<DT><U>Function:</U> <B>null-environment</B>
+<DD><P>
+
+<VAR>Version</VAR> must be an exact non-negative integer <VAR>n</VAR>
+corresponding to a version of one of the Revised^<VAR>n</VAR> Reports on
+Scheme. <CODE>Scheme-report-environment</CODE> returns a specifier for an
+environment that contains the set of bindings specified in the
+corresponding report that the implementation supports.
+<CODE>Null-environment</CODE> returns a specifier for an environment that
+contains only the (syntactic) bindings for all the syntactic keywords
+defined in the given version of the report.
+</P>
+<P>
+
+Not all versions may be available in all implementations at all times.
+However, an implementation that conforms to version <VAR>n</VAR> of the
+Revised^<VAR>n</VAR> Reports on Scheme must accept version <VAR>n</VAR>. An error
+is signalled if the specified version is not available.
+</P>
+<P>
+
+The effect of assigning (through the use of <CODE>eval</CODE>) a variable
+bound in a <CODE>scheme-report-environment</CODE> (for example <CODE>car</CODE>) is
+unspecified. Thus the environments specified by
+<CODE>scheme-report-environment</CODE> may be immutable.
+</P>
+<P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1475"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>interaction-environment</B>
+<DD><P>
+
+This optional procedure returns a specifier for the environment that
+contains implementation-defined bindings, typically a superset of those
+listed in the report. The intent is that this procedure will return the
+environment in which the implementation would evaluate expressions
+dynamically typed by the user.
+</P>
+</DL>
+<P>
+
+Here are some more <CODE>eval</CODE> examples:
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(require 'eval)
+=> #&lt;unspecified&gt;
+(define car 'volvo)
+=> #&lt;unspecified&gt;
+car
+=> volvo
+(eval 'car (interaction-environment))
+=> volvo
+(eval 'car (scheme-report-environment 5))
+=> #&lt;primitive-procedure car&gt;
+(eval '(eval 'car (interaction-environment))
+ (scheme-report-environment 5))
+=> volvo
+(eval '(eval '(set! car 'buick) (interaction-environment))
+ (scheme-report-environment 5))
+=> #&lt;unspecified&gt;
+car
+=> buick
+(eval 'car (scheme-report-environment 5))
+=> #&lt;primitive-procedure car&gt;
+(eval '(eval 'car (interaction-environment))
+ (scheme-report-environment 5))
+=> buick
+</pre></td></tr></table><P>
+
+<A NAME="Values"></A>
+<HR SIZE="6">
+<A NAME="SEC247"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC246"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC248"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC235"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.4.12 Values </H3>
+<!--docid::SEC247::-->
+<P>
+
+<CODE>(require 'values)</CODE>
+<A NAME="IDX1476"></A>
+</P>
+<P>
+
+<A NAME="IDX1477"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>values</B> <I>obj <small>...</small></I>
+<DD><CODE>values</CODE> takes any number of arguments, and passes (returns) them
+to its continuation.
+</DL>
+<P>
+
+<A NAME="IDX1478"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>call-with-values</B> <I>thunk proc</I>
+<DD><VAR>thunk</VAR> must be a procedure of no arguments, and <VAR>proc</VAR> must be
+a procedure. <CODE>call-with-values</CODE> calls <VAR>thunk</VAR> with a
+continuation that, when passed some values, calls <VAR>proc</VAR> with those
+values as arguments.
+<P>
+
+Except for continuations created by the <CODE>call-with-values</CODE>
+procedure, all continuations take exactly one value, as now; the effect
+of passing no value or more than one value to continuations that were
+not created by the <CODE>call-with-values</CODE> procedure is
+unspecified.
+</P>
+</DL>
+<P>
+
+<A NAME="SRFI"></A>
+<HR SIZE="6">
+<A NAME="SEC248"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC247"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC249"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC235"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.4.13 SRFI </H3>
+<!--docid::SEC248::-->
+<P>
+
+<CODE>(require 'srfi)</CODE>
+<A NAME="IDX1479"></A>
+</P>
+<P>
+
+Implements <EM>Scheme Request For Implementation</EM> (SRFI) as
+<A NAME="IDX1480"></A>
+described at <A HREF="http://srfi.schemers.org/">http://srfi.schemers.org/</A>
+</P>
+<P>
+
+The Copyright terms of each SRFI states:
+<BLOCKQUOTE>
+&quot;However, this document itself may not be modified in any way, ...&quot;
+</BLOCKQUOTE>
+<P>
+
+Therefore, the specification of SRFI constructs must not be
+quoted without including the complete SRFI document containing
+discussion and a sample implementation program.
+</P>
+<P>
+
+<A NAME="IDX1481"></A>
+</P>
+<DL>
+<DT><U>Macro:</U> <B>cond-expand</B> <I>&lt;clause1&gt; &lt;clause2&gt; <small>...</small></I>
+<DD><P>
+
+<EM>Syntax:</EM>
+Each &lt;clause&gt; should be of the form
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=display><pre style="font-family: serif"><TT>(&lt;feature&gt; &lt;expression1&gt; <small>...</small>)</TT>
+</pre></td></tr></table><P>
+
+where &lt;feature&gt; is a boolean expression composed of symbols and
+`and', `or', and `not' of boolean expressions. The last &lt;clause&gt;
+may be an &quot;else clause,&quot; which has the form
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=display><pre style="font-family: serif"><TT>(else &lt;expression1&gt; &lt;expression2&gt; <small>...</small>).</TT>
+</pre></td></tr></table><P>
+
+The first clause whose feature expression is satisfied is expanded.
+If no feature expression is satisfied and there is no else clause, an
+error is signaled.
+</P>
+<P>
+
+SLIB <CODE>cond-expand</CODE> is an extension of SRFI-0,
+<A HREF="http://srfi.schemers.org/srfi-0/srfi-0.html">http://srfi.schemers.org/srfi-0/srfi-0.html</A>.
+</P>
+</DL>
+<P>
+
+<TABLE BORDER="0" CELLSPACING="0">
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC249">7.4.13.1 SRFI-1</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">list-processing</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC260">7.4.13.2 SRFI-2</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">guarded LET* special form</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC261">7.4.13.3 SRFI-8</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Binding to multiple values</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC262">7.4.13.4 SRFI-9</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Defining Record Types</TD></TR>
+</TABLE>
+<P>
+
+<A NAME="SRFI-1"></A>
+<HR SIZE="6">
+<A NAME="SEC249"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC248"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC260"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC248"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H4> 7.4.13.1 SRFI-1 </H4>
+<!--docid::SEC249::-->
+<P>
+
+<CODE>(require 'srfi-1)</CODE>
+<A NAME="IDX1482"></A>
+</P>
+<P>
+
+Implements the <EM>SRFI-1</EM> <EM>list-processing library</EM> as described
+<A NAME="IDX1483"></A>
+<A NAME="IDX1484"></A>
+at <A HREF="http://srfi.schemers.org/srfi-1/srfi-1.html">http://srfi.schemers.org/srfi-1/srfi-1.html</A>
+</P>
+<P>
+
+<A NAME="SEC250"></A>
+<H3> Constructors </H3>
+<!--docid::SEC250::-->
+<P>
+
+<A NAME="IDX1485"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>xcons</B> <I>d a</I>
+<DD><CODE>(define (xcons d a) (cons a d))</CODE>.
+</DL>
+<P>
+
+<A NAME="IDX1486"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>list-tabulate</B> <I>len proc</I>
+<DD>Returns a list of length <VAR>len</VAR>. Element <VAR>i</VAR> is <CODE>(<VAR>proc</VAR>
+<VAR>i</VAR>)</CODE> for 0 &lt;= <VAR>i</VAR> &lt; <VAR>len</VAR>.
+</DL>
+<P>
+
+<A NAME="IDX1487"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>cons*</B> <I>obj1 obj2</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1488"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>list-copy</B> <I>flist</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1489"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>iota</B> <I>count start step</I>
+<DD><P>
+
+<A NAME="IDX1490"></A>
+<DT><U>Function:</U> <B>iota</B> <I>count start</I>
+<DD></P>
+<P>
+
+<A NAME="IDX1491"></A>
+<DT><U>Function:</U> <B>iota</B> <I>count</I>
+<DD>Returns a list of <VAR>count</VAR> numbers: (<VAR>start</VAR>, <VAR>start</VAR>+<VAR>step</VAR>, <small>...</small>, <VAR>start</VAR>+(<VAR>count</VAR>-1)*<VAR>step</VAR>).
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1492"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>circular-list</B> <I>obj1 obj2 <small>...</small></I>
+<DD><P>
+
+Returns a circular list of <VAR>obj1</VAR>, <VAR>obj2</VAR>, <small>...</small>.
+</P>
+</DL>
+<A NAME="SEC251"></A>
+<H3> Predicates </H3>
+<!--docid::SEC251::-->
+<P>
+
+<A NAME="IDX1493"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>proper-list?</B> <I>obj</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1494"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>circular-list?</B> <I>x</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1495"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>dotted-list?</B> <I>obj</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1496"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>null-list?</B> <I>obj</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1497"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>not-pair?</B> <I>obj</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1498"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>list=</B> <I>=pred list <small>...</small></I>
+<DD><P>
+
+</P>
+</DL>
+<A NAME="SEC252"></A>
+<H3> Selectors </H3>
+<!--docid::SEC252::-->
+<P>
+
+<A NAME="IDX1499"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>first</B> <I>pair</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1500"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>second</B> <I>pair</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1501"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>third</B> <I>pair</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1502"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>fourth</B> <I>pair</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1503"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>fifth</B> <I>pair</I>
+<DD><A NAME="IDX1504"></A>
+<DT><U>Function:</U> <B>sixth</B> <I>obj</I>
+<DD><A NAME="IDX1505"></A>
+<DT><U>Function:</U> <B>seventh</B> <I>obj</I>
+<DD><A NAME="IDX1506"></A>
+<DT><U>Function:</U> <B>eighth</B> <I>obj</I>
+<DD><A NAME="IDX1507"></A>
+<DT><U>Function:</U> <B>ninth</B> <I>obj</I>
+<DD><A NAME="IDX1508"></A>
+<DT><U>Function:</U> <B>tenth</B> <I>obj</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1509"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>car+cdr</B> <I>pair</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1510"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>drop</B> <I>lst k</I>
+<DD><A NAME="IDX1511"></A>
+<DT><U>Function:</U> <B>take</B> <I>lst k</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1512"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>take!</B> <I>lst k</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1513"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>take-right</B> <I>lst k</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1514"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>drop-right</B> <I>lst k</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1515"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>drop-right!</B> <I>lst k</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1516"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>split-at</B> <I>lst k</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1517"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>split-at!</B> <I>lst k</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1518"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>last</B> <I>lst</I>
+<DD><P>
+
+(car (last-pair lst))
+</P>
+</DL>
+<A NAME="SEC253"></A>
+<H3> Miscellaneous </H3>
+<!--docid::SEC253::-->
+<P>
+
+<A NAME="IDX1519"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>length+</B> <I>obj</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1520"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>concatenate</B> <I>lists</I>
+<DD><A NAME="IDX1521"></A>
+<DT><U>Function:</U> <B>concatenate!</B> <I>lists</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1522"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>reverse!</B> <I>lst</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1523"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>append-reverse</B> <I>rev-head tail</I>
+<DD><A NAME="IDX1524"></A>
+<DT><U>Function:</U> <B>append-reverse!</B> <I>rev-head tail</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1525"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>zip</B> <I>list1 list2 <small>...</small></I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1526"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>unzip1</B> <I>lst</I>
+<DD><A NAME="IDX1527"></A>
+<DT><U>Function:</U> <B>unzip2</B> <I>lst</I>
+<DD><A NAME="IDX1528"></A>
+<DT><U>Function:</U> <B>unzip3</B> <I>lst</I>
+<DD><A NAME="IDX1529"></A>
+<DT><U>Function:</U> <B>unzip4</B> <I>lst</I>
+<DD><A NAME="IDX1530"></A>
+<DT><U>Function:</U> <B>unzip5</B> <I>lst</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1531"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>count</B> <I>pred list1 list2 <small>...</small></I>
+<DD><P>
+
+</P>
+</DL>
+<A NAME="SEC254"></A>
+<H3> Fold and Unfold </H3>
+<!--docid::SEC254::-->
+<P>
+
+<A NAME="IDX1532"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>map!</B> <I>f list1 clist2 <small>...</small></I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1533"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>pair-for-each</B> <I>f clist1 clist2 <small>...</small></I>
+<DD><P>
+
+</P>
+</DL>
+<A NAME="SEC255"></A>
+<H3> Filtering and Partitioning </H3>
+<!--docid::SEC255::-->
+<P>
+
+<A NAME="IDX1534"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>filter</B> <I>pred lis</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1535"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>filter!</B> <I>pred l</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1536"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>partition</B> <I>pred list</I>
+<DD><P>
+
+</P>
+</DL>
+<A NAME="SEC256"></A>
+<H3> Searching </H3>
+<!--docid::SEC256::-->
+<P>
+
+<A NAME="IDX1537"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>find</B> <I>pred list</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1538"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>find-tail</B> <I>pred list</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1539"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>remove</B> <I>pred l</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1540"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>remove!</B> <I>pred l</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1541"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>any</B> <I>pred clist1 clist2 <small>...</small></I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1542"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>list-index</B> <I>pred clist1 clist2 <small>...</small></I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1543"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>span</B> <I>pred list</I>
+<DD><P>
+
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1544"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>member</B> <I>obj list pred</I>
+<DD><P>
+
+<A NAME="IDX1545"></A>
+<DT><U>Function:</U> <B>member</B> <I>obj list</I>
+<DD></P>
+<P>
+
+<CODE>member</CODE> returns the first sublist of <VAR>list</VAR> whose car is <VAR>obj</VAR>, where the sublists
+of <VAR>list</VAR> are the non-empty lists returned by <TT>(list-tail <VAR>list</VAR> <VAR>k</VAR>)</TT>
+for <VAR>k</VAR> less than the length of <VAR>list</VAR>. If <VAR>obj</VAR> does not occur in <VAR>list</VAR>,
+then <TT>#f</TT> (not the empty list) is returned. The procedure <VAR>pred</VAR> is
+used for testing equality. If <VAR>pred</VAR> is not provided, `<SAMP>equal?</SAMP>' is
+used.
+</P>
+</DL>
+<A NAME="SEC257"></A>
+<H3> Deleting </H3>
+<!--docid::SEC257::-->
+<P>
+
+<A NAME="SEC258"></A>
+<H3> Association lists </H3>
+<!--docid::SEC258::-->
+<P>
+
+<A NAME="IDX1546"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>assoc</B> <I>obj alist pred</I>
+<DD><P>
+
+<A NAME="IDX1547"></A>
+<DT><U>Function:</U> <B>assoc</B> <I>obj alist</I>
+<DD></P>
+<P>
+
+<VAR>alist</VAR> (for &quot;association list&quot;) must be a list of pairs. These
+procedures find the first pair in <VAR>alist</VAR> whose car field is <VAR>obj</VAR>, and
+returns that pair. If no pair in <VAR>alist</VAR> has <VAR>obj</VAR> as its car, then <TT>#f</TT>
+(not the empty list) is returned. The procedure <VAR>pred</VAR> is used for
+testing equality. If <VAR>pred</VAR> is not provided, `<SAMP>equal?</SAMP>' is used.
+</P>
+</DL>
+<A NAME="SEC259"></A>
+<H3> Set operations </H3>
+<!--docid::SEC259::-->
+<P>
+
+<A NAME="SRFI-2"></A>
+<HR SIZE="6">
+<A NAME="SEC260"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC249"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC261"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC248"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H4> 7.4.13.2 SRFI-2 </H4>
+<!--docid::SEC260::-->
+<P>
+
+<CODE>(require 'srfi-2)</CODE>
+<A NAME="IDX1548"></A>
+</P>
+<P>
+
+<A NAME="IDX1549"></A>
+</P>
+<DL>
+<DT><U>Macro:</U> <B>and-let*</B> <I>claws body <small>...</small></I>
+<DD><P>
+
+<A HREF="http://srfi.schemers.org/srfi-2/srfi-2.html">http://srfi.schemers.org/srfi-2/srfi-2.html</A>
+</P>
+</DL>
+<P>
+
+<A NAME="SRFI-8"></A>
+<HR SIZE="6">
+<A NAME="SEC261"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC260"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC262"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC248"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H4> 7.4.13.3 SRFI-8 </H4>
+<!--docid::SEC261::-->
+<P>
+
+<CODE>(require 'srfi-8)</CODE>
+<A NAME="IDX1550"></A>
+</P>
+<P>
+
+<A NAME="IDX1551"></A>
+</P>
+<DL>
+<DT><U>Special Form:</U> <B>receive</B> <I>formals expression body <small>...</small></I>
+<DD><P>
+
+<A HREF="http://srfi.schemers.org/srfi-8/srfi-8.html">http://srfi.schemers.org/srfi-8/srfi-8.html</A>
+</P>
+</DL>
+<P>
+
+<A NAME="SRFI-9"></A>
+<HR SIZE="6">
+<A NAME="SEC262"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC261"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC263"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC248"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H4> 7.4.13.4 SRFI-9 </H4>
+<!--docid::SEC262::-->
+<P>
+
+<CODE>(require 'srfi-9)</CODE>
+<A NAME="IDX1552"></A>
+</P>
+<P>
+
+<A HREF="http://srfi.schemers.org/srfi-9/srfi-9.html">http://srfi.schemers.org/srfi-9/srfi-9.html</A>
+</P>
+<P>
+
+<A NAME="IDX1553"></A>
+</P>
+<DL>
+<DT><U>Special Form:</U> <B>define-record-type</B> <I>&lt;type-name&gt; (&lt;constructor-name&gt; &lt;field-tag&gt; ...) &lt;predicate-name&gt; &lt;field spec&gt; ...</I>
+<DD><P>
+
+Where
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>&lt;field-spec&gt; == (&lt;field-tag&gt; &lt;accessor-name&gt;)
+ == (&lt;field-tag&gt; &lt;accessor-name&gt; &lt;modifier-name&gt;)
+
+</pre></td></tr></table><P>
+
+<CODE>define-record-type</CODE> is a syntax wrapper for the SLIB
+<CODE>record</CODE> module.
+</P>
+</DL>
+<P>
+
+<A NAME="Session Support"></A>
+<HR SIZE="6">
+<A NAME="SEC263"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC262"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC264"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H2> 7.5 Session Support </H2>
+<!--docid::SEC263::-->
+<P>
+
+<TABLE BORDER="0" CELLSPACING="0">
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC264">7.5.1 Repl</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Macros at top-level</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC265">7.5.2 Quick Print</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Loop-safe Output</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC266">7.5.3 Debug</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">To err is human ...</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC267">7.5.4 Breakpoints</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">Pause execution</TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC268">7.5.5 Tracing</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP">'trace</TD></TR>
+</TABLE>
+<P>
+
+<A NAME="Repl"></A>
+<HR SIZE="6">
+<A NAME="SEC264"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC263"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC265"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC263"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.5.1 Repl </H3>
+<!--docid::SEC264::-->
+<P>
+
+<CODE>(require 'repl)</CODE>
+<A NAME="IDX1554"></A>
+</P>
+<P>
+
+Here is a read-eval-print-loop which, given an eval, evaluates forms.
+</P>
+<P>
+
+<A NAME="IDX1555"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>repl:top-level</B> <I>repl:eval</I>
+<DD><CODE>read</CODE>s, <CODE>repl:eval</CODE>s and <CODE>write</CODE>s expressions from
+<CODE>(current-input-port)</CODE> to <CODE>(current-output-port)</CODE> until an
+end-of-file is encountered. <CODE>load</CODE>, <CODE>slib:eval</CODE>,
+<CODE>slib:error</CODE>, and <CODE>repl:quit</CODE> dynamically bound during
+<CODE>repl:top-level</CODE>.
+</DL>
+<P>
+
+<A NAME="IDX1556"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>repl:quit</B>
+<DD>Exits from the invocation of <CODE>repl:top-level</CODE>.
+</DL>
+<P>
+
+The <CODE>repl:</CODE> procedures establish, as much as is possible to do
+portably, a top level environment supporting macros.
+<CODE>repl:top-level</CODE> uses <CODE>dynamic-wind</CODE> to catch error conditions
+and interrupts. If your implementation supports this you are all set.
+</P>
+<P>
+
+Otherwise, if there is some way your implementation can catch error
+conditions and interrupts, then have them call <CODE>slib:error</CODE>. It
+will display its arguments and reenter <CODE>repl:top-level</CODE>.
+<CODE>slib:error</CODE> dynamically bound by <CODE>repl:top-level</CODE>.
+</P>
+<P>
+
+To have your top level loop always use macros, add any interrupt
+catching lines and the following lines to your Scheme init file:
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(require 'macro)
+<A NAME="IDX1557"></A>(require 'repl)
+<A NAME="IDX1558"></A>(repl:top-level macro:eval)
+</pre></td></tr></table><P>
+
+<A NAME="Quick Print"></A>
+<HR SIZE="6">
+<A NAME="SEC265"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC264"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC266"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC263"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.5.2 Quick Print </H3>
+<!--docid::SEC265::-->
+<P>
+
+<CODE>(require 'qp)</CODE>
+<A NAME="IDX1559"></A>
+</P>
+<P>
+
+When displaying error messages and warnings, it is paramount that the
+output generated for circular lists and large data structures be
+limited. This section supplies a procedure to do this. It could be
+much improved.
+</P>
+<P>
+
+<BLOCKQUOTE>
+Notice that the neccessity for truncating output eliminates
+Common-Lisp's <A HREF="slib_4.html#SEC53">4.2 Format (version 3.0)</A> from consideration; even when variables
+<CODE>*print-level*</CODE> and <CODE>*print-level*</CODE> are set, huge strings and
+bit-vectors are <EM>not</EM> limited.
+</BLOCKQUOTE>
+<P>
+
+<A NAME="IDX1560"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>qp</B> <I>arg1 <small>...</small></I>
+<DD><A NAME="IDX1561"></A>
+<DT><U>Procedure:</U> <B>qpn</B> <I>arg1 <small>...</small></I>
+<DD><A NAME="IDX1562"></A>
+<DT><U>Procedure:</U> <B>qpr</B> <I>arg1 <small>...</small></I>
+<DD><CODE>qp</CODE> writes its arguments, separated by spaces, to
+<CODE>(current-output-port)</CODE>. <CODE>qp</CODE> compresses printing by
+substituting `<SAMP>...</SAMP>' for substructure it does not have sufficient
+room to print. <CODE>qpn</CODE> is like <CODE>qp</CODE> but outputs a newline
+before returning. <CODE>qpr</CODE> is like <CODE>qpn</CODE> except that it returns
+its last argument.
+</DL>
+<P>
+
+<A NAME="IDX1563"></A>
+</P>
+<DL>
+<DT><U>Variable:</U> <B>*qp-width*</B>
+<DD><VAR>*qp-width*</VAR> is the largest number of characters that <CODE>qp</CODE>
+should use. If <VAR>*qp-width*</VAR> is #f, then all items will be
+<CODE>write</CODE>n. If <VAR>*qp-width*</VAR> is 0, then all items except
+procedures will be <CODE>write</CODE>n; procedures will be indicated by
+`<SAMP>#[proc]</SAMP>'.
+</DL>
+<P>
+
+<A NAME="Debug"></A>
+<HR SIZE="6">
+<A NAME="SEC266"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC265"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC267"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC263"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.5.3 Debug </H3>
+<!--docid::SEC266::-->
+<P>
+
+<CODE>(require 'debug)</CODE>
+<A NAME="IDX1564"></A>
+</P>
+<P>
+
+Requiring <CODE>debug</CODE> automatically requires <CODE>trace</CODE> and
+<CODE>break</CODE>.
+</P>
+<P>
+
+An application with its own datatypes may want to substitute its own
+printer for <CODE>qp</CODE>. This example shows how to do this:
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define qpn (lambda args) <small>...</small>)
+(provide 'qp)
+(require 'debug)
+<A NAME="IDX1565"></A></pre></td></tr></table><P>
+
+<A NAME="IDX1566"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>trace-all</B> <I>file <small>...</small></I>
+<DD>Traces (see section <A HREF="slib_7.html#SEC268">7.5.5 Tracing</A>) all procedures <CODE>define</CODE>d at top-level in
+`<TT>file</TT>' <small>...</small>.
+<P>
+
+<A NAME="IDX1567"></A>
+<DT><U>Procedure:</U> <B>track-all</B> <I>file <small>...</small></I>
+<DD>Tracks (see section <A HREF="slib_7.html#SEC268">7.5.5 Tracing</A>) all procedures <CODE>define</CODE>d at top-level in
+`<TT>file</TT>' <small>...</small>.
+</P>
+<P>
+
+<A NAME="IDX1568"></A>
+<DT><U>Procedure:</U> <B>stack-all</B> <I>file <small>...</small></I>
+<DD>Stacks (see section <A HREF="slib_7.html#SEC268">7.5.5 Tracing</A>) all procedures <CODE>define</CODE>d at top-level in
+`<TT>file</TT>' <small>...</small>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1569"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>break-all</B> <I>file <small>...</small></I>
+<DD>Breakpoints (see section <A HREF="slib_7.html#SEC267">7.5.4 Breakpoints</A>) all procedures <CODE>define</CODE>d at
+top-level in `<TT>file</TT>' <small>...</small>.
+</DL>
+<P>
+
+<A NAME="Breakpoints"></A>
+<HR SIZE="6">
+<A NAME="SEC267"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC266"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC268"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC263"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.5.4 Breakpoints </H3>
+<!--docid::SEC267::-->
+<P>
+
+<CODE>(require 'break)</CODE>
+<A NAME="IDX1570"></A>
+</P>
+<P>
+
+<A NAME="IDX1571"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>init-debug</B>
+<DD>If your Scheme implementation does not support <CODE>break</CODE> or
+<CODE>abort</CODE>, a message will appear when you <CODE>(require 'break)</CODE> or
+<A NAME="IDX1572"></A>
+<CODE>(require 'debug)</CODE> telling you to type <CODE>(init-debug)</CODE>. This
+<A NAME="IDX1573"></A>
+is in order to establish a top-level continuation. Typing
+<CODE>(init-debug)</CODE> at top level sets up a continuation for
+<CODE>break</CODE>.
+</DL>
+<P>
+
+<A NAME="IDX1574"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>breakpoint</B> <I>arg1 <small>...</small></I>
+<DD>Returns from the top level continuation and pushes the continuation from
+which it was called on a continuation stack.
+</DL>
+<P>
+
+<A NAME="IDX1575"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>continue</B>
+<DD>Pops the topmost continuation off of the continuation stack and returns
+an unspecified value to it.
+<P>
+
+<A NAME="IDX1576"></A>
+<DT><U>Function:</U> <B>continue</B> <I>arg1 <small>...</small></I>
+<DD>Pops the topmost continuation off of the continuation stack and returns
+<VAR>arg1</VAR> <small>...</small> to it.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1577"></A>
+</P>
+<DL>
+<DT><U>Macro:</U> <B>break</B> <I>proc1 <small>...</small></I>
+<DD>Redefines the top-level named procedures given as arguments so that
+<CODE>breakpoint</CODE> is called before calling <VAR>proc1</VAR> <small>...</small>.
+<A NAME="IDX1578"></A>
+<DT><U>Macro:</U> <B>break</B>
+<DD>With no arguments, makes sure that all the currently broken identifiers
+are broken (even if those identifiers have been redefined) and returns a
+list of the broken identifiers.
+</DL>
+<P>
+
+<A NAME="IDX1579"></A>
+</P>
+<DL>
+<DT><U>Macro:</U> <B>unbreak</B> <I>proc1 <small>...</small></I>
+<DD>Turns breakpoints off for its arguments.
+<A NAME="IDX1580"></A>
+<DT><U>Macro:</U> <B>unbreak</B>
+<DD>With no arguments, unbreaks all currently broken identifiers and returns
+a list of these formerly broken identifiers.
+</DL>
+<P>
+
+These are <EM>procedures</EM> for breaking. If defmacros are not natively
+supported by your implementation, these might be more convenient to use.
+</P>
+<P>
+
+<A NAME="IDX1581"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>breakf</B> <I>proc</I>
+<DD><A NAME="IDX1582"></A>
+<DT><U>Function:</U> <B>breakf</B> <I>proc name</I>
+<DD>To break, type
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(set! <VAR>symbol</VAR> (breakf <VAR>symbol</VAR>))
+</pre></td></tr></table>or
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(set! <VAR>symbol</VAR> (breakf <VAR>symbol</VAR> '<VAR>symbol</VAR>))
+</pre></td></tr></table>or
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define <VAR>symbol</VAR> (breakf <VAR>function</VAR>))
+</pre></td></tr></table>or
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define <VAR>symbol</VAR> (breakf <VAR>function</VAR> '<VAR>symbol</VAR>))
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1583"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>unbreakf</B> <I>proc</I>
+<DD>To unbreak, type
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(set! <VAR>symbol</VAR> (unbreakf <VAR>symbol</VAR>))
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="Trace"></A>
+<HR SIZE="6">
+<A NAME="SEC268"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC267"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC269"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC263"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.5.5 Tracing </H3>
+<!--docid::SEC268::-->
+<P>
+
+<CODE>(require 'trace)</CODE>
+<A NAME="IDX1584"></A>
+</P>
+<P>
+
+This feature provides three ways to monitor procedure invocations:
+</P>
+<P>
+
+</P>
+<DL COMPACT>
+<DT>stack
+<DD>Pushes the procedure-name when the procedure is called; pops when it
+returns.
+<DT>track
+<DD>Pushes the procedure-name and arguments when the procedure is called;
+pops when it returns.
+<DT>trace
+<DD>Pushes the procedure-name and prints `<SAMP>CALL <VAR>procedure-name</VAR>
+<VAR>arg1</VAR> <small>...</small></SAMP>' when the procdure is called; pops and prints
+`<SAMP>RETN <VAR>procedure-name</VAR> <VAR>value</VAR></SAMP>' when the procedure returns.
+</DL>
+<P>
+
+<A NAME="IDX1585"></A>
+</P>
+<DL>
+<DT><U>Variable:</U> <B>debug:max-count</B>
+<DD>If a traced procedure calls itself or untraced procedures which call it,
+stack, track, and trace will limit the number of stack pushes to
+<VAR>debug:max-count</VAR>.
+</DL>
+<P>
+
+<A NAME="IDX1586"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>print-call-stack</B>
+<DD><A NAME="IDX1587"></A>
+<DT><U>Function:</U> <B>print-call-stack</B> <I>port</I>
+<DD>Prints the call-stack to <VAR>port</VAR> or the current-error-port.
+</DL>
+<P>
+
+<A NAME="IDX1588"></A>
+</P>
+<DL>
+<DT><U>Macro:</U> <B>trace</B> <I>proc1 <small>...</small></I>
+<DD>Traces the top-level named procedures given as arguments.
+<A NAME="IDX1589"></A>
+<DT><U>Macro:</U> <B>trace</B>
+<DD>With no arguments, makes sure that all the currently traced identifiers
+are traced (even if those identifiers have been redefined) and returns a
+list of the traced identifiers.
+</DL>
+<P>
+
+<A NAME="IDX1590"></A>
+</P>
+<DL>
+<DT><U>Macro:</U> <B>track</B> <I>proc1 <small>...</small></I>
+<DD>Traces the top-level named procedures given as arguments.
+<A NAME="IDX1591"></A>
+<DT><U>Macro:</U> <B>track</B>
+<DD>With no arguments, makes sure that all the currently tracked identifiers
+are tracked (even if those identifiers have been redefined) and returns
+a list of the tracked identifiers.
+</DL>
+<P>
+
+<A NAME="IDX1592"></A>
+</P>
+<DL>
+<DT><U>Macro:</U> <B>stack</B> <I>proc1 <small>...</small></I>
+<DD>Traces the top-level named procedures given as arguments.
+<A NAME="IDX1593"></A>
+<DT><U>Macro:</U> <B>stack</B>
+<DD>With no arguments, makes sure that all the currently stacked identifiers
+are stacked (even if those identifiers have been redefined) and returns
+a list of the stacked identifiers.
+</DL>
+<P>
+
+<A NAME="IDX1594"></A>
+</P>
+<DL>
+<DT><U>Macro:</U> <B>untrace</B> <I>proc1 <small>...</small></I>
+<DD>Turns tracing, tracking, and off for its arguments.
+<A NAME="IDX1595"></A>
+<DT><U>Macro:</U> <B>untrace</B>
+<DD>With no arguments, untraces all currently traced identifiers and returns
+a list of these formerly traced identifiers.
+</DL>
+<P>
+
+<A NAME="IDX1596"></A>
+</P>
+<DL>
+<DT><U>Macro:</U> <B>untrack</B> <I>proc1 <small>...</small></I>
+<DD>Turns tracing, tracking, and off for its arguments.
+<A NAME="IDX1597"></A>
+<DT><U>Macro:</U> <B>untrack</B>
+<DD>With no arguments, untracks all currently tracked identifiers and returns
+a list of these formerly tracked identifiers.
+</DL>
+<P>
+
+<A NAME="IDX1598"></A>
+</P>
+<DL>
+<DT><U>Macro:</U> <B>unstack</B> <I>proc1 <small>...</small></I>
+<DD>Turns tracing, stacking, and off for its arguments.
+<A NAME="IDX1599"></A>
+<DT><U>Macro:</U> <B>unstack</B>
+<DD>With no arguments, unstacks all currently stacked identifiers and returns
+a list of these formerly stacked identifiers.
+</DL>
+<P>
+
+These are <EM>procedures</EM> for tracing. If defmacros are not natively
+supported by your implementation, these might be more convenient to use.
+</P>
+<P>
+
+<A NAME="IDX1600"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>tracef</B> <I>proc</I>
+<DD><A NAME="IDX1601"></A>
+<DT><U>Function:</U> <B>tracef</B> <I>proc name</I>
+<DD><A NAME="IDX1602"></A>
+<DT><U>Function:</U> <B>trackf</B> <I>proc</I>
+<DD><A NAME="IDX1603"></A>
+<DT><U>Function:</U> <B>trackf</B> <I>proc name</I>
+<DD><A NAME="IDX1604"></A>
+<DT><U>Function:</U> <B>stackf</B> <I>proc</I>
+<DD><A NAME="IDX1605"></A>
+<DT><U>Function:</U> <B>stackf</B> <I>proc name</I>
+<DD>To trace, type
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(set! <VAR>symbol</VAR> (tracef <VAR>symbol</VAR>))
+</pre></td></tr></table>or
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(set! <VAR>symbol</VAR> (tracef <VAR>symbol</VAR> '<VAR>symbol</VAR>))
+</pre></td></tr></table>or
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define <VAR>symbol</VAR> (tracef <VAR>function</VAR>))
+</pre></td></tr></table>or
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(define <VAR>symbol</VAR> (tracef <VAR>function</VAR> '<VAR>symbol</VAR>))
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="IDX1606"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>untracef</B> <I>proc</I>
+<DD>Removes tracing, tracking, or stacking for <VAR>proc</VAR>.
+To untrace, type
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(set! <VAR>symbol</VAR> (untracef <VAR>symbol</VAR>))
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="System Interface"></A>
+<HR SIZE="6">
+<A NAME="SEC269"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC268"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC270"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H2> 7.6 System Interface </H2>
+<!--docid::SEC269::-->
+<P>
+
+If <CODE>(provided? 'getenv)</CODE>:
+</P>
+<P>
+
+<A NAME="IDX1607"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>getenv</B> <I>name</I>
+<DD>Looks up <VAR>name</VAR>, a string, in the program environment. If <VAR>name</VAR> is
+found a string of its value is returned. Otherwise, <CODE>#f</CODE> is returned.
+</DL>
+<P>
+
+If <CODE>(provided? 'system)</CODE>:
+</P>
+<P>
+
+<A NAME="IDX1608"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>system</B> <I>command-string</I>
+<DD>Executes the <VAR>command-string</VAR> on the computer and returns the
+integer status code.
+</DL>
+<P>
+
+<TABLE BORDER="0" CELLSPACING="0">
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC270">7.6.1 Directories</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC271">7.6.2 Transactions</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
+<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="slib_7.html#SEC275">7.6.3 CVS</A></TD><TD>&nbsp;&nbsp;</TD><TD ALIGN="left" VALIGN="TOP"></TD></TR>
+</TABLE>
+<P>
+
+<A NAME="Directories"></A>
+<HR SIZE="6">
+<A NAME="SEC270"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC269"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC271"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC269"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.6.1 Directories </H3>
+<!--docid::SEC270::-->
+<P>
+
+<CODE>(require 'directory)</CODE>
+<A NAME="IDX1609"></A>
+</P>
+<P>
+
+<A NAME="IDX1610"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>current-directory</B>
+<DD><P>
+
+<CODE>current-directory</CODE> returns a string containing the absolute file
+name representing the current working directory. If this string
+cannot be obtained, #f is returned.
+</P>
+<P>
+
+If <CODE>current-directory</CODE> cannot be supported by the platform, then #f is returned.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1611"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>make-directory</B> <I>name</I>
+<DD><P>
+
+Creates a sub-directory <VAR>name</VAR> of the current-directory. If
+successful, <CODE>make-directory</CODE> returns #t; otherwise #f.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1612"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>directory-for-each</B> <I>proc directory</I>
+<DD><P>
+
+<VAR>proc</VAR> must be a procedure taking one argument.
+`<SAMP>Directory-For-Each</SAMP>' applies <VAR>proc</VAR> to the (string) name of
+each file in <VAR>directory</VAR>. The dynamic order in which <VAR>proc</VAR> is
+applied to the filenames is unspecified. The value returned by
+`<SAMP>directory-for-each</SAMP>' is unspecified.
+</P>
+<P>
+
+<A NAME="IDX1613"></A>
+<DT><U>Function:</U> <B>directory-for-each</B> <I>proc directory pred</I>
+<DD>Applies <VAR>proc</VAR> only to those filenames for which the procedure
+<VAR>pred</VAR> returns a non-false value.
+</P>
+<P>
+
+<A NAME="IDX1614"></A>
+<DT><U>Function:</U> <B>directory-for-each</B> <I>proc directory match</I>
+<DD>Applies <VAR>proc</VAR> only to those filenames for which
+<CODE>(filename:match?? <VAR>match</VAR>)</CODE> would return a non-false value
+(see section `Filenames' in <CITE>SLIB</CITE>).
+</P>
+<P>
+
+<TABLE><tr><td>&nbsp;</td><td class=example><pre>(require 'directory)
+(directory-for-each print &quot;.&quot; &quot;[A-Z]*.scm&quot;)
+-|
+&quot;Bev2slib.scm&quot;
+&quot;Template.scm&quot;
+</pre></td></tr></table></DL>
+<P>
+
+<A NAME="Transactions"></A>
+<HR SIZE="6">
+<A NAME="SEC271"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC270"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC275"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC269"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.6.2 Transactions </H3>
+<!--docid::SEC271::-->
+<P>
+
+If <CODE>system</CODE> is provided by the Scheme implementation, the
+<EM>transact</EM> package provides functions for file-locking and
+file-replacement transactions.
+</P>
+<P>
+
+<CODE>(require 'transact)</CODE>
+<A NAME="IDX1615"></A>
+</P>
+<P>
+
+<A NAME="SEC272"></A>
+<H4> File Locking </H4>
+<!--docid::SEC272::-->
+<P>
+
+Unix file-locking is focussed on write permissions for segments of a
+existing file. While this might be employed for (binary) database
+access, it is not used for everyday contention (between users) for
+text files.
+</P>
+<P>
+
+Microsoft has several file-locking protocols. Their model denies
+write access to a file if any reader has it open. This is too
+restrictive. Write access is denied even when the reader has
+reached end-of-file. And tracking read access (which is much more
+common than write access) causes havoc when remote hosts crash or
+disconnect.
+</P>
+<P>
+
+It is bizarre that the concept of multi-user contention for
+modifying files has not been adequately addressed by either of the
+large operating system development efforts. There is further irony
+that both camps support contention detection and resolution only
+through weak conventions of some their document editing programs.
+</P>
+<P>
+
+<A NAME="IDX1616"></A>
+The <EM>file-lock</EM> procedures implement a transaction method for file
+<A NAME="IDX1617"></A>
+replacement compatible with the methods used by the GNU <EM>emacs</EM>
+<A NAME="IDX1618"></A>
+text editor on Unix systems and the Microsoft <EM>Word</EM> editor.
+<A NAME="IDX1619"></A>
+<A NAME="IDX1620"></A>
+</P>
+<P>
+
+<A NAME="IDX1621"></A>
+Both protocols employ what I term a <EM>certificate</EM> containing the
+<A NAME="IDX1622"></A>
+user, hostname, time, and (on Unix) process-id.
+Intent to replace <VAR>file</VAR> is indicated by adding to <VAR>file</VAR>'s
+directory a certificate object whose name is derived from
+<VAR>file</VAR>.
+</P>
+<P>
+
+The Microsoft Word certificate is contained in a 162 byte file named
+for the visited <VAR>file</VAR> with a `<SAMP>~$</SAMP>' prefix.
+Emacs/Unix creates a symbolic link to a certificate named for the
+visited <VAR>file</VAR> prefixed with `<SAMP>.#</SAMP>'.
+Because Unix systems can import Microsoft file systems, these
+routines maintain and check both Emacs and Word certificates.
+</P>
+<P>
+
+<A NAME="IDX1623"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>file-lock-owner</B> <I>path</I>
+<DD><P>
+
+Returns the string `<SAMP><VAR>user</VAR>@<VAR>hostname</VAR></SAMP>' associated with
+the lock owner of file <VAR>path</VAR> if locked; and #f otherwise.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1624"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>file-lock!</B> <I>path email</I>
+<DD><P>
+
+<A NAME="IDX1625"></A>
+<DT><U>Procedure:</U> <B>file-lock!</B> <I>path</I>
+<DD></P>
+<P>
+
+<VAR>path</VAR> must be a string naming the file to be locked. If supplied, <VAR>email</VAR>
+must be a string formatted as `<SAMP><VAR>user</VAR>@<VAR>hostname</VAR></SAMP>'. If
+absent, <VAR>email</VAR> defaults to the value returned by <CODE>user-email-address</CODE>.
+</P>
+<P>
+
+If <VAR>path</VAR> is already locked, then <CODE>file-lock!</CODE> returns `<SAMP>#f</SAMP>'. If <VAR>path</VAR> is
+unlocked, then <CODE>file-lock!</CODE> returns the certificate string associated with the
+new lock for file <VAR>path</VAR>.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1626"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>file-unlock!</B> <I>path certificate</I>
+<DD><P>
+
+<VAR>path</VAR> must be a string naming the file to be unlocked. <VAR>certificate</VAR> must be the
+string returned by <CODE>file-lock!</CODE> for <VAR>path</VAR>.
+</P>
+<P>
+
+If <VAR>path</VAR> is locked with <VAR>certificate</VAR>, then <CODE>file-unlock!</CODE> removes the locks and returns
+`<SAMP>#t</SAMP>'. Otherwise, <CODE>file-unlock!</CODE> leaves the file system unaltered and returns
+`<SAMP>#f</SAMP>'.
+</P>
+</DL>
+<A NAME="SEC273"></A>
+<H4> File Transactions </H4>
+<!--docid::SEC273::-->
+<P>
+
+<A NAME="IDX1627"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>emacs:backup-name</B> <I>path backup-style</I>
+<DD><P>
+
+<VAR>path</VAR> must be a string. <VAR>backup-style</VAR> must be a symbol. Depending on <VAR>backup-style</VAR>, <CODE>emacs:backup-name</CODE>
+returns:
+</P>
+<DL COMPACT>
+<DT>none
+<DD>#f
+<DT>simple
+<DD>the string &quot;<VAR>path</VAR>~&quot;
+<DT>numbered
+<DD>the string &quot;<VAR>path</VAR>.~<VAR>n</VAR>~&quot;, where <VAR>n</VAR> is one greater than the
+highest number appearing in a filename matching &quot;<VAR>path</VAR>.~*~&quot;. <VAR>n</VAR>
+defauls to 1 when no filename matches.
+<DT>existing
+<DD>the string &quot;<VAR>path</VAR>.~<VAR>n</VAR>~&quot; if a numbered backup already exists in
+this directory; otherwise. &quot;<VAR>path</VAR>~&quot;
+<DT>orig
+<DD>the string &quot;<VAR>path</VAR>.orig&quot;
+<DT>bak
+<DD>the string &quot;<VAR>path</VAR>.bak&quot;
+</DL>
+</DL>
+<P>
+
+<A NAME="IDX1628"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>transact-file-replacement</B> <I>proc path backup-style certificate</I>
+<DD><P>
+
+<A NAME="IDX1629"></A>
+<DT><U>Function:</U> <B>transact-file-replacement</B> <I>proc path backup-style</I>
+<DD></P>
+<P>
+
+<A NAME="IDX1630"></A>
+<DT><U>Function:</U> <B>transact-file-replacement</B> <I>proc path</I>
+<DD></P>
+<P>
+
+<VAR>path</VAR> must be a string naming an existing file. <VAR>backup-style</VAR> is one of the
+symbols none, simple, numbered, existing, orig,
+bak or #f; with meanings described above; or a string naming
+the location of a backup file. <VAR>backup-style</VAR> defaults to #f. If supplied,
+<VAR>certificate</VAR> is the certificate with which <VAR>path</VAR> is locked.
+</P>
+<P>
+
+<VAR>proc</VAR> must be a procedure taking two string arguments:
+<UL>
+<LI>
+<VAR>path</VAR>, the original filename (to be read); and
+<LI>
+a temporary file-name.
+</UL>
+<P>
+
+If <VAR>path</VAR> is locked by other than <VAR>certificate</VAR>, or if <VAR>certificate</VAR> is supplied and <VAR>path</VAR> is not
+locked, then <CODE>transact-file-replacement</CODE> returns #f. If <VAR>certificate</VAR> is not supplied, then, <CODE>transact-file-replacement</CODE> creates
+temporary (Emacs and Word) locks for <VAR>path</VAR> during the transaction. The
+lock status of <VAR>path</VAR> will be restored before <CODE>transact-file-replacement</CODE> returns.
+</P>
+<P>
+
+<CODE>transact-file-replacement</CODE> calls <VAR>proc</VAR> with <VAR>path</VAR> (which should not be modified) and a temporary
+file path to be written.
+If <VAR>proc</VAR> returns any value other than #t, then the file named by <VAR>path</VAR>
+is not altered and <CODE>transact-file-replacement</CODE> returns #f.
+Otherwise, <CODE>emacs:backup-name</CODE> is called with <VAR>path</VAR> and <VAR>backup-style</VAR>. If it
+returns a string, then <VAR>path</VAR> is renamed to it.
+</P>
+<P>
+
+Finally, the temporary file is renamed <VAR>path</VAR>.
+<CODE>transact-file-replacement</CODE> returns #t if <VAR>path</VAR> was successfully replaced; and #f otherwise.
+</P>
+</DL>
+<A NAME="SEC274"></A>
+<H4> Identification </H4>
+<!--docid::SEC274::-->
+<P>
+
+<A NAME="IDX1631"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>user-email-address</B>
+<DD><P>
+
+<CODE>user-email-address</CODE> returns a string of the form `<SAMP>username@hostname</SAMP>'. If
+this e-mail address cannot be obtained, #f is returned.
+</P>
+</DL>
+<P>
+
+<A NAME="CVS"></A>
+<HR SIZE="6">
+<A NAME="SEC275"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC271"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC276"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC269"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H3> 7.6.3 CVS </H3>
+<!--docid::SEC275::-->
+<P>
+
+<CODE>(require 'cvs)</CODE>
+<A NAME="IDX1632"></A>
+</P>
+<P>
+
+<A NAME="IDX1633"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>cvs-files</B> <I>directory/</I>
+<DD>Returns a list of the local pathnames (with prefix <VAR>directory/</VAR>) of all
+CVS controlled files in <VAR>directory/</VAR> and in <VAR>directory/</VAR>'s subdirectories.
+</DL>
+<P>
+
+<A NAME="IDX1634"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>cvs-directories</B> <I>directory/</I>
+<DD>Returns a list of all of <VAR>directory/</VAR> and all <VAR>directory/</VAR>'s CVS controlled
+subdirectories.
+</DL>
+<P>
+
+<A NAME="IDX1635"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>cvs-root</B> <I>path/</I>
+<DD>Returns the (string) contents of <VAR>path/</VAR>CVS/Root;
+or <CODE>(getenv &quot;CVSROOT&quot;)</CODE> if Root doesn't exist.
+</DL>
+<P>
+
+<A NAME="IDX1636"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>cvs-repository</B> <I>directory/</I>
+<DD>Returns the (string) contents of <VAR>directory/</VAR>CVS/Root appended
+with <VAR>directory/</VAR>CVS/Repository; or #f if <VAR>directory/</VAR>CVS/Repository
+doesn't exist.
+</DL>
+<P>
+
+<A NAME="IDX1637"></A>
+</P>
+<DL>
+<DT><U>Procedure:</U> <B>cvs-set-root!</B> <I>new-root directory/</I>
+<DD><P>
+
+Writes <VAR>new-root</VAR> to file CVS/Root of <VAR>directory/</VAR> and all its subdirectories.
+</P>
+</DL>
+<P>
+
+<A NAME="IDX1638"></A>
+</P>
+<DL>
+<DT><U>Function:</U> <B>cvs-vet</B> <I>directory/</I>
+<DD><P>
+
+Signals an error if CVS/Repository or CVS/Root files in <VAR>directory/</VAR> or any
+subdirectory do not match.
+</P>
+</DL>
+<P>
+
+<A NAME="Extra-SLIB Packages"></A>
+<HR SIZE="6">
+<A NAME="SEC276"></A>
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC275"> &lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> Up </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<H2> 7.7 Extra-SLIB Packages </H2>
+<!--docid::SEC276::-->
+<P>
+
+Several Scheme packages have been written using SLIB. There are several
+reasons why a package might not be included in the SLIB distribution:
+<UL>
+<LI>
+Because it requires special hardware or software which is not universal.
+<LI>
+Because it is large and of limited interest to most Scheme users.
+<LI>
+Because it has copying terms different enough from the other SLIB
+packages that its inclusion would cause confusion.
+<LI>
+Because it is an application program, rather than a library module.
+<LI>
+Because I have been too busy to integrate it.
+</UL>
+<P>
+
+Once an optional package is installed (and an entry added to
+<CODE>*catalog*</CODE>, the <CODE>require</CODE> mechanism allows it to be called up
+and used as easily as any other SLIB package. Some optional packages
+(for which <CODE>*catalog*</CODE> already has entries) available from SLIB
+sites are:
+</P>
+<P>
+
+</P>
+<DL COMPACT>
+<DT>SLIB-PSD
+<DD>is a portable debugger for Scheme (requires emacs editor).
+<P>
+
+&lt;A HREF=&quot;http://swissnet.ai.mit.edu/ftpdir/scm/slib-psd1-3.tar.gz&quot;&gt;
+http://swissnet.ai.mit.edu/ftpdir/scm/slib-psd1-3.tar.gz
+&lt;/A&gt;
+</P>
+<P>
+
+swissnet.ai.mit.edu:/pub/scm/slib-psd1-3.tar.gz
+</P>
+<P>
+
+ftp.maths.tcd.ie:pub/bosullvn/jacal/slib-psd1-3.tar.gz
+</P>
+<P>
+
+ftp.cs.indiana.edu:/pub/scheme-repository/utl/slib-psd1-3.tar.gz
+</P>
+<P>
+
+With PSD, you can run a Scheme program in an Emacs buffer, set
+breakpoints, single step evaluation and access and modify the program's
+variables. It works by instrumenting the original source code, so it
+should run with any R4RS compliant Scheme. It has been tested with SCM,
+Elk 1.5, and the sci interpreter in the Scheme-&gt;C system, but should
+work with other Schemes with a minimal amount of porting, if at
+all. Includes documentation and user's manual. Written by Pertti
+Kellom\&quot;aki, pk @ cs.tut.fi. The Lisp Pointers article describing PSD
+(Lisp Pointers VI(1):15-23, January-March 1993) is available as
+&lt;A HREF=&quot;http://www.cs.tut.fi/staff/pk/scheme/psd/article/article.html&quot;&gt;
+http://www.cs.tut.fi/staff/pk/scheme/psd/article/article.html
+&lt;/A&gt;
+</P>
+<P>
+
+</P>
+<DT>SCHELOG
+<DD>is an embedding of Prolog in Scheme.<BR>
+&lt;A HREF=&quot;http://www.ccs.neu.edu/~dorai/schelog/schelog.html&quot;&gt;
+http://www.ccs.neu.edu/~dorai/schelog/schelog.html
+&lt;/A&gt;
+<P>
+
+</P>
+<DT>JFILTER
+<DD>is a Scheme program which converts text among the JIS, EUC, and
+Shift-JIS Japanese character sets.<BR>
+&lt;A HREF=&quot;http://www.sci.toyama-u.ac.jp/~iwao/Scheme/Jfilter/index.html&quot;&gt;
+http://www.sci.toyama-u.ac.jp/~iwao/Scheme/Jfilter/index.html
+&lt;/A&gt;
+</DL>
+<P>
+
+<A NAME="About SLIB"></A>
+<HR SIZE="6">
+<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
+<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_7.html#SEC183"> &lt;&lt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_8.html#SEC277"> &gt;&gt; </A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT"> &nbsp; <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib.html#SEC_Top">Top</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_toc.html#SEC_Contents">Contents</A>]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[Index]</TD>
+<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="slib_abt.html#SEC_About"> ? </A>]</TD>
+</TR></TABLE>
+<BR>
+<FONT SIZE="-1">
+This document was generated
+by <I>Steve Langasek</I> on <I>January, 10 2005</I>
+using <A HREF="http://texi2html.cvshome.org"><I>texi2html</I></A>
+</FONT>
+
+</BODY>
+</HTML>