This is scm.info, produced by makeinfo version 4.3 from scm.texi. INFO-DIR-SECTION The Algorithmic Language Scheme START-INFO-DIR-ENTRY * SCM: (scm). A Scheme interpreter. END-INFO-DIR-ENTRY  File: scm.info, Node: Top, Next: Overview, Prev: (dir), Up: (dir) This manual documents the SCM Scheme implementation. SCM version 5d6 was released May 2002. The most recent information about SCM can be found on SCM's "WWW" home page: Copyright (C) 1990-1999 Free Software Foundation Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the author. * Menu: * Overview:: * Installing SCM:: * Operational Features:: * The Language:: Reference. * Packages:: Optional Capabilities. * The Implementation:: How it works. * Index::  File: scm.info, Node: Overview, Next: Installing SCM, Prev: Top, Up: Top Overview ******** Scm is a portable Scheme implementation written in C. Scm provides a machine independent platform for [JACAL], a symbolic algebra system. * Menu: * SCM Features:: * SCM Authors:: * Copying:: * Bibliography::  File: scm.info, Node: SCM Features, Next: SCM Authors, Prev: Overview, Up: Overview Features ======== * Conforms to Revised^5 Report on the Algorithmic Language Scheme [R5RS] and the [IEEE] P1178 specification. * Support for [SICP], [R2RS], [R3RS], and [R5RS] scheme code. * Runs under Amiga, Atari-ST, MacOS, MS-DOS, OS/2, NOS/VE, Unicos, VMS, Unix and similar systems. Supports ASCII and EBCDIC character sets. * Is fully documented in TeXinfo form, allowing documentation to be generated in info, TeX, html, nroff, and troff formats. * Supports inexact real and complex numbers, 30 bit immediate integers and large precision integers. * Many Common Lisp functions: `logand', `logor', `logxor', `lognot', `ash', `logcount', `integer-length', `bit-extract', `defmacro', `macroexpand', `macroexpand1', `gentemp', `defvar', `force-output', `software-type', `get-decoded-time', `get-internal-run-time', `get-internal-real-time', `delete-file', `rename-file', `copy-tree', `acons', and `eval'. * `Char-code-limit', `most-positive-fixnum', `most-negative-fixnum', `and internal-time-units-per-second' constants. `*Features*' and `*load-pathname*' variables. * Arrays and bit-vectors. String ports and software emulation ports. I/O extensions providing ANSI C and POSIX.1 facilities. * Interfaces to standard libraries including REGEX string regular expression matching and the CURSES screen management package. * Available add-on packages including an interactive debugger, database, X-window graphics, BGI graphics, Motif, and Open-Windows packages. * A compiler (HOBBIT, available separately) and dynamic linking of compiled modules. * User definable responses to interrupts and errors, Process-syncronization primitives. Setable levels of monitoring and timing information printed interactively (the `verbose' function). `Restart', `quit', and `exec'.  File: scm.info, Node: SCM Authors, Next: Copying, Prev: SCM Features, Up: Overview Authors ======= Aubrey Jaffer (jaffer @ alum.mit.edu) Most of SCM. Radey Shouman Arrays, `gsubr's, compiled closures, records, Ecache, syntax-rules macros, and "safeport"s. Jerry D. Hedden Real and Complex functions. Fast mixed type arithmetics. Hugh Secker-Walker Syntax checking and memoization of special forms by evaluator. Storage allocation strategy and parameters. George Carrette "Siod", written by George Carrette, was the starting point for SCM. The major innovations taken from Siod are the evaluator's use of the C-stack and being able to garbage collect off the C-stack (*note Garbage Collection::). There are many other contributors to SCM. They are acknowledged in the file `ChangeLog', a log of changes that have been made to scm.  File: scm.info, Node: Copying, Next: Bibliography, Prev: SCM Authors, Up: Overview Copyright ========= Authors have assigned their SCM copyrights to: Free Software Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111, USA Permission to use, copy, modify, distribute, and sell this software and its documentation for any purpose is hereby granted without fee, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation. NO WARRANTY BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SIOD copyright ============== COPYRIGHT (c) 1989 BY PARADIGM ASSOCIATES INCORPORATED, CAMBRIDGE, MASSACHUSETTS. ALL RIGHTS RESERVED Permission to use, copy, modify, distribute and sell this software and its documentation for any purpose and without fee is hereby granted, provided that the above copyright notice appear in all copies and that both that copyright notice and this permission notice appear in supporting documentation, and that the name of Paradigm Associates Inc not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission. PARADIGM DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL PARADIGM BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. gjc@paradigm.com Phone: 617-492-6079 Paradigm Associates Inc 29 Putnam Ave, Suite 6 Cambridge, MA 02138  File: scm.info, Node: Bibliography, Prev: Copying, Up: Overview Bibliography ============ [IEEE] `IEEE Standard 1178-1990. IEEE Standard for the Scheme Programming Language.' IEEE, New York, 1991. [R4RS] William Clinger and Jonathan Rees, Editors. Revised(4) Report on the Algorithmic Language Scheme. `ACM Lisp Pointers' Volume IV, Number 3 (July-September 1991), pp. 1-55. *Note Top: (r4rs)Top. [R5RS] Richard Kelsey and William Clinger and Jonathan (Rees, editors) Revised(5) Report on the Algorithmic Language Scheme. `Higher-Order and Symbolic Computation' Volume 11, Number 1 (1998), pp. 7-105, and `ACM SIGPLAN Notices' 33(9), September 1998. *Note Top: (r5rs)Top. [Exrename] William Clinger Hygienic Macros Through Explicit Renaming `Lisp Pointers' Volume IV, Number 4 (December 1991), pp 17-23. [SICP] Harold Abelson and Gerald Jay Sussman with Julie Sussman. `Structure and Interpretation of Computer Programs.' MIT Press, Cambridge, 1985. [Simply] Brian Harvey and Matthew Wright. `Simply Scheme: Introducing Computer Science' MIT Press, 1994 ISBN 0-262-08226-8 [SchemePrimer] 犬飼大(Dai Inukai) `入門Scheme' 1999年12月初版 ISBN4-87966-954-7 [SLIB] Todd R. Eigenschink, Dave Love, and Aubrey Jaffer. SLIB, The Portable Scheme Library. Version 2c8, June 2000. *Note Top: (slib)Top. [JACAL] Aubrey Jaffer. JACAL Symbolic Mathematics System. Version 1b0, Sep 1999. *Note Top: (jacal)Top. `scm.texi' `scm.info' Documentation of `scm' extensions (beyond Scheme standards). Documentation on the internal representation and how to extend or include `scm' in other programs. `Xlibscm.texi' `Xlibscm.info' Documentation of the Xlib - SCM Language X Interface.  File: scm.info, Node: Installing SCM, Next: Operational Features, Prev: Overview, Up: Top Installing SCM ************** * Menu: * Making SCM:: Bootstrapping. * SLIB:: REQUIREd reading. * Building SCM:: * Installing Dynamic Linking:: * Configure Module Catalog:: * Saving Images:: Make Fast-Booting Executables * Automatic C Preprocessor Definitions:: * Problems Compiling:: * Problems Linking:: * Problems Running:: * Testing:: * Reporting Problems::  File: scm.info, Node: Making SCM, Next: SLIB, Prev: Installing SCM, Up: Installing SCM Making SCM ========== The SCM distribution has "Makefile" which contains rules for making "scmlit", a "bare-bones" version of SCM sufficient for running `build'. `build' is used to compile (or create scripts to compile) full featured versions. Makefiles are not portable to the majority of platforms. If `Makefile' works for you, good; If not, I don't want to hear about it. If you need to compile SCM without build, there are several ways to proceed: * Use the build (http://swissnet.ai.mit.edu/~jaffer/buildscm.html) web page to create custom batch scripts for compiling SCM. * Use SCM on a different platform to run `build' to create a script to build SCM; * Use another implementation of Scheme to run `build' to create a script to build SCM; * Create your own script or `Makefile'.  File: scm.info, Node: SLIB, Next: Building SCM, Prev: Making SCM, Up: Installing SCM SLIB ==== [SLIB] is a portable Scheme library meant to provide compatibility and utility functions for all standard Scheme implementations. Although SLIB is not _neccessary_ to run SCM, I strongly suggest you obtain and install it. Bug reports about running SCM without SLIB have very low priority. SLIB is available from the same sites as SCM: * swissnet.ai.mit.edu:/pub/scm/slib2d4.tar.gz * ftp.gnu.org:/pub/gnu/jacal/slib2d4.tar.gz * ftp.cs.indiana.edu:/pub/scheme-repository/imp/slib2d4.tar.gz Unpack SLIB (`tar xzf slib2d4.tar.gz' or `unzip -ao slib2d4.zip') in an appropriate directory for your system; both `tar' and `unzip' will create the directory `slib'. Then create a file `require.scm' in the SCM "implementation-vicinity" (this is the same directory as where the file `Init5d6.scm' is installed). `require.scm' should have the contents: (define (library-vicinity) "/usr/local/lib/slib/") (load (in-vicinity (library-vicinity) "require")) where the pathname string `/usr/local/lib/slib/' is to be replaced by the pathname into which you installed SLIB. Absolute pathnames are recommended here; if you use a relative pathname, SLIB can get confused when the working directory is changed (*note chmod: I/O-Extensions.). The way to specify a relative pathname is to append it to the implementation-vicinity, which is absolute: (define library-vicinity (let ((lv (string-append (implementation-vicinity) "../slib/"))) (lambda () lv))) (load (in-vicinity (library-vicinity) "require")) Alternatively, you can set the (shell) environment variable `SCHEME_LIBRARY_PATH' to the pathname of the SLIB directory (*note SCHEME_LIBRARY_PATH: SCM Variables.). If set, the environment variable overrides `require.scm'. Again, absolute pathnames are recommended.  File: scm.info, Node: Building SCM, Next: Installing Dynamic Linking, Prev: SLIB, Up: Installing SCM Building SCM ============ The file "build" loads the file "build.scm", which constructs a relational database of how to compile and link SCM executables. `build.scm' has information for the platforms which SCM has been ported to (of which I have been notified). Some of this information is old, incorrect, or incomplete. Send corrections and additions to jaffer @ ai.mit.edu. * Menu: * Invoking Build:: * Build Options:: * Compiling and Linking Custom Files::  File: scm.info, Node: Invoking Build, Next: Build Options, Prev: Building SCM, Up: Building SCM Invoking Build -------------- The _all_ method will also work for MS-DOS and unix. Use the _all_ method if you encounter problems with `build'. MS-DOS From the SCM source directory, type `build' followed by up to 9 command line arguments. unix From the SCM source directory, type `./build' followed by command line arguments. _all_ From the SCM source directory, start `scm' or `scmlit' and type `(load "build")'. Alternatively, start `scm' or `scmlit' with the command line argument `-ilbuild'. Invoking build without the `-F' option will build or create a shell script with the `arrays', `inexact', and `bignums' options as defaults. bash$ ./build -| #! /bin/sh # unix (linux) script created by SLIB/batch # ================ Write file with C defines rm -f scmflags.h echo '#define IMPLINIT "Init5d6.scm"'>>scmflags.h echo '#define BIGNUMS'>>scmflags.h echo '#define FLOATS'>>scmflags.h echo '#define ARRAYS'>>scmflags.h # ================ Compile C source files gcc -O2 -c continue.c scm.c scmmain.c findexec.c script.c time.c repl.c scl.c eval.c sys.c subr.c debug.c unif.c rope.c # ================ Link C object files gcc -rdynamic -o scm continue.o scm.o scmmain.o findexec.o script.o time.o repl.o scl.o eval.o sys.o subr.o debug.o unif.o rope.o -lm -lc To cross compile for another platform, invoke build with the `-p' or `--platform=' option. This will create a script for the platform named in the `-p' or `--platform=' option. bash$ ./build -o scmlit -p darwin -F lit -| #! /bin/sh # unix (darwin) script created by SLIB/batch # ================ Write file with C defines rm -f scmflags.h echo '#define IMPLINIT "Init5d6.scm"'>>scmflags.h # ================ Compile C source files cc -O3 -c continue.c scm.c scmmain.c findexec.c script.c time.c repl.c scl.c eval.c sys.c subr.c debug.c unif.c rope.c # ================ Link C object files mv -f scmlit scmlit~ cc -o scmlit continue.o scm.o scmmain.o findexec.o script.o time.o repl.o scl.o eval.o sys.o subr.o debug.o unif.o rope.o  File: scm.info, Node: Build Options, Next: Compiling and Linking Custom Files, Prev: Invoking Build, Up: Building SCM Build Options ------------- The options to "build" specify what, where, and how to build a SCM program or dynamically linked module. These options are unrelated to the SCM command line options. - Build Option: -p PLATFORM-NAME - Build Option: --platform=PLATFORM-NAME specifies that the compilation should be for a computer/operating-system combination called PLATFORM-NAME. _Note:_ The case of PLATFORM-NAME is distinguised. The current PLATFORM-NAMEs are all lower-case. The platforms defined by table "platform" in `build.scm' are: Table: platform name processor operating-system compiler #f processor-family operating-system #f symbol processor-family operating-system symbol symbol atom symbol symbol ================= ================= ================= ================= *unknown* *unknown* unix cc acorn-unixlib acorn *unknown* cc aix powerpc aix cc alpha alpha osf1 cc alpha-elf alpha unix cc alpha-linux alpha linux gcc amiga-aztec m68000 amiga cc amiga-dice-c m68000 amiga dcc amiga-gcc m68000 amiga gcc amiga-sas m68000 amiga lc atari-st-gcc m68000 atari.st gcc atari-st-turbo-c m68000 atari.st tcc borland-c 8086 ms-dos bcc cygwin32 i386 unix gcc darwin powerpc unix cc djgpp i386 ms-dos gcc freebsd i386 unix cc gcc *unknown* unix gcc highc i386 ms-dos hc386 hp-ux hp-risc hp-ux cc irix mips irix gcc linux i386 linux gcc linux-aout i386 linux gcc microsoft-c 8086 ms-dos cl microsoft-c-nt i386 ms-dos cl microsoft-quick-c 8086 ms-dos qcl ms-dos 8086 ms-dos cc openbsd *unknown* unix gcc os/2-cset i386 os/2 icc os/2-emx i386 os/2 gcc sunos sparc sunos cc svr4 *unknown* unix cc svr4-gcc-sun-ld sparc sunos gcc turbo-c 8086 ms-dos tcc unicos cray unicos cc unix *unknown* unix cc vms vax vms cc vms-gcc vax vms gcc watcom-9.0 i386 ms-dos wcc386p - Build Option: -o FILENAME - Build Option: --outname=FILENAME specifies that the compilation should produce an executable or object name of FILENAME. The default is `scm'. Executable suffixes will be added if neccessary, e.g. `scm' => `scm.exe'. - Build Option: -l LIBNAME ... - Build Option: --libraries=LIBNAME specifies that the LIBNAME should be linked with the executable produced. If compile flags or include directories (`-I') are needed, they are automatically supplied for compilations. The `c' library is always included. SCM "features" specify any libraries they need; so you shouldn't need this option often. - Build Option: -D DEFINITION ... - Build Option: --defines=DEFINITION specifies that the DEFINITION should be made in any C source compilations. If compile flags or include directories (`-I') are needed, they are automatically supplied for compilations. SCM "features" specify any flags they need; so you shouldn't need this option often. - Build Option: --compiler-options=FLAG specifies that that FLAG will be put on compiler command-lines. - Build Option: --linker-options=FLAG specifies that that FLAG will be put on linker command-lines. - Build Option: -s PATHNAME - Build Option: --scheme-initial=PATHNAME specifies that PATHNAME should be the default location of the SCM initialization file `Init5d6.scm'. SCM tries several likely locations before resorting to PATHNAME (*note File-System Habitat::). If not specified, the current directory (where build is building) is used. - Build Option: -c PATHNAME ... - Build Option: --c-source-files=PATHNAME specifies that the C source files PATHNAME ... are to be compiled. - Build Option: -j PATHNAME ... - Build Option: --object-files=PATHNAME specifies that the object files PATHNAME ... are to be linked. - Build Option: -i CALL ... - Build Option: --initialization=CALL specifies that the C functions CALL ... are to be invoked during initialization. - Build Option: -t BUILD-WHAT - Build Option: --type=BUILD-WHAT specifies in general terms what sort of thing to build. The choices are: `exe' executable program. `lib' library module. `dlls' archived dynamically linked library object files. `dll' dynamically linked library object file. The default is to build an executable. - Build Option: -h BATCH-SYNTAX - Build Option: -batch-dialect=BATCH-SYNTAX specifies how to build. The default is to create a batch file for the host system. The SLIB file `batch.scm' knows how to create batch files for: * unix * dos * vms * amigaos (was amigados) * system This option executes the compilation and linking commands through the use of the `system' procedure. * *unknown* This option outputs Scheme code. - Build Option: -w BATCH-FILENAME - Build Option: -script-name=BATCH-FILENAME specifies where to write the build script. The default is to display it on `(current-output-port)'. - Build Option: -F FEATURE ... - Build Option: --features=FEATURE specifies to build the given features into the executable. The defined features are: "array" Alias for ARRAYS "array-for-each" array-map! and array-for-each (arrays must also be featured). "arrays" Use if you want arrays, uniform-arrays and uniform-vectors. "bignums" Large precision integers. "careful-interrupt-masking" Define this for extra checking of interrupt masking and some simple checks for proper use of malloc and free. This is for debugging C code in `sys.c', `eval.c', `repl.c' and makes the interpreter several times slower than usual. "cautious" Normally, the number of arguments arguments to interpreted closures (from LAMBDA) are checked if the function part of a form is not a symbol or only the first time the form is executed if the function part is a symbol. defining `reckless' disables any checking. If you want to have SCM always check the number of arguments to interpreted closures define feature `cautious'. "cheap-continuations" If you only need straight stack continuations, executables compile with this feature will run faster and use less storage than not having it. Machines with unusual stacks _need_ this. Also, if you incorporate new C code into scm which uses VMS system services or library routines (which need to unwind the stack in an ordrly manner) you may need to use this feature. "compiled-closure" Use if you want to use compiled closures. "curses" For the "curses" screen management package. "debug" Turns on the features `cautious', `careful-interrupt-masking', and `stack-limit'; uses `-g' flags for debugging SCM source code. "dump" Convert a running scheme program into an executable file. "dynamic-linking" Be able to load compiled files while running. "edit-line" interface to the editline or GNU readline library. "engineering-notation" Use if you want floats to display in engineering notation (exponents always multiples of 3) instead of scientific notation. "generalized-c-arguments" `make_gsubr' for arbitrary (< 11) arguments to C functions. "i/o-extensions" Commonly available I/O extensions: "exec", line I/O, file positioning, file delete and rename, and directory functions. "inexact" Use if you want floating point numbers. "lit" Lightweight - no features "macro" C level support for hygienic and referentially transparent macros (syntax-rules macros). "mysql" Client connections to the mysql databases. "no-heap-shrink" Use if you want segments of unused heap to not be freed up after garbage collection. This may increase time in GC for *very* large working sets. "none" No features "posix" Posix functions available on all "Unix-like" systems. fork and process functions, user and group IDs, file permissions, and "link". "reckless" If your scheme code runs without any errors you can disable almost all error checking by compiling all files with `reckless'. "record" The Record package provides a facility for user to define their own record data types. See SLIB for documentation. "regex" String regular expression matching. "rev2-procedures" These procedures were specified in the `Revised^2 Report on Scheme' but not in `R4RS'. "sicp" Use if you want to run code from: Harold Abelson and Gerald Jay Sussman with Julie Sussman. `Structure and Interpretation of Computer Programs.' The MIT Press, Cambridge, Massachusetts, USA, 1985. Differences from R5RS are: * (eq? '() '#f) * (define a 25) returns the symbol a. * (set! a 36) returns 36. "single-precision-only" Use if you want all inexact real numbers to be single precision. This only has an effect if SINGLES is also defined (which is the default). This does not affect complex numbers. "socket" BSD "socket" interface. "stack-limit" Use to enable checking for stack overflow. Define value of the C preprocessor variable STACK_LIMIT to be the size to which SCM should allow the stack to grow. STACK_LIMIT should be less than the maximum size the hardware can support, as not every routine checks the stack. "tick-interrupts" Use if you want the ticks and ticks-interrupt functions. "turtlegr" "Turtle" graphics calls for both Borland-C and X11 from sjm@ee.tut.fi. "unix" Those unix features which have not made it into the Posix specs: nice, acct, lstat, readlink, symlink, mknod and sync. "windows" Microsoft Windows executable. "x" Alias for Xlib feature. "xlib" Interface to Xlib graphics routines.  File: scm.info, Node: Compiling and Linking Custom Files, Prev: Build Options, Up: Building SCM Compiling and Linking Custom Files ---------------------------------- A correspondent asks: How can we link in our own c files to the SCM interpreter so that we can add our own functionality? (e.g. we have a bunch of tcp functions we want access to). Would this involve changing build.scm or the Makefile or both? (*note Changing Scm:: has instructions describing the C code format). Suppose a C file "foo.c" has functions you wish to add to SCM. To compile and link your file at compile time, use the `-c' and `-i' options to build: bash$ build -c foo.c -i init_foo -| #! /bin/sh rm -f scmflags.h echo '#define IMPLINIT "/home/jaffer/scm/Init5d6.scm"'>>scmflags.h echo '#define COMPILED_INITS init_foo();'>>scmflags.h echo '#define BIGNUMS'>>scmflags.h echo '#define FLOATS'>>scmflags.h echo '#define ARRAYS'>>scmflags.h gcc -O2 -c continue.c scm.c findexec.c script.c time.c repl.c scl.c \ eval.c sys.c subr.c unif.c rope.c foo.c gcc -rdynamic -o scm continue.o scm.o findexec.o script.o time.o \ repl.o scl.o eval.o sys.o subr.o unif.o rope.o foo.o -lm -lc To make a dynamically loadable object file use the `-t dll' option: bash$ build -t dll -c foo.c -| #! /bin/sh rm -f scmflags.h echo '#define IMPLINIT "/home/jaffer/scm/Init5d6.scm"'>>scmflags.h echo '#define BIGNUMS'>>scmflags.h echo '#define FLOATS'>>scmflags.h echo '#define ARRAYS'>>scmflags.h echo '#define DLL'>>scmflags.h gcc -O2 -fpic -c foo.c gcc -shared -o foo.so foo.o -lm -lc Once `foo.c' compiles correctly (and your SCM build supports dynamic-loading), you can load the compiled file with the Scheme command `(load "./foo.so")'. See *Note Configure Module Catalog:: for how to add a compiled dll file to SLIB's catalog.  File: scm.info, Node: Installing Dynamic Linking, Next: Configure Module Catalog, Prev: Building SCM, Up: Installing SCM Installing Dynamic Linking ========================== Dynamic linking has not been ported to all platforms. Operating systems in the BSD family (a.out binary format) can usually be ported to "DLD". The "dl" library (`#define SUN_DL' for SCM) was a proposed POSIX standard and may be available on other machines with "COFF" binary format. For notes about porting to MS-Windows and finishing the port to VMS *Note Finishing Dynamic Linking::. "DLD" is a library package of C functions that performs "dynamic link editing" on Linux, VAX (Ultrix), Sun 3 (SunOS 3.4 and 4.0), SPARCstation (SunOS 4.0), Sequent Symmetry (Dynix), and Atari ST. It is available from: * ftp.gnu.org:pub/gnu/dld-3.3.tar.gz These notes about using libdl on SunOS are from `gcc.info': On a Sun, linking using GNU CC fails to find a shared library and reports that the library doesn't exist at all. This happens if you are using the GNU linker, because it does only static linking and looks only for unshared libraries. If you have a shared library with no unshared counterpart, the GNU linker won't find anything. We hope to make a linker which supports Sun shared libraries, but please don't ask when it will be finished-we don't know. Sun forgot to include a static version of `libdl.a' with some versions of SunOS (mainly 4.1). This results in undefined symbols when linking static binaries (that is, if you use `-static'). If you see undefined symbols `_dlclose', `_dlsym' or `_dlopen' when linking, compile and link against the file `mit/util/misc/dlsym.c' from the MIT version of X windows.  File: scm.info, Node: Configure Module Catalog, Next: Saving Images, Prev: Installing Dynamic Linking, Up: Installing SCM Configure Module Catalog ======================== The SLIB module "catalog" can be extended to define other `require'-able packages by adding calls to the Scheme source file `mkimpcat.scm'. Within `mkimpcat.scm', the following procedures are defined. - Function: add-link feature object-file lib1 ... FEATURE should be a symbol. OBJECT-FILE should be a string naming a file containing compiled "object-code". Each LIBn argument should be either a string naming a library file or `#f'. If OBJECT-FILE exists, the `add-link' procedure registers symbol FEATURE so that the first time `require' is called with the symbol FEATURE as its argument, OBJECT-FILE and the LIB1 ... are dynamically linked into the executing SCM session. If OBJECT-FILE exists, `add-link' returns `#t', otherwise it returns `#f'. For example, to install a compiled dll `foo', add these lines to `mkimpcat.scm': (add-link 'foo (in-vicinity (implementation-vicinity) "foo" link:able-suffix)) - Function: add-alias alias feature ALIAS and FEATURE are symbols. The procedure `add-alias' registers ALIAS as an alias for FEATURE. An unspecified value is returned. `add-alias' causes `(require 'ALIAS)' to behave like `(require 'FEATURE)'. - Function: add-source feature filename FEATURE is a symbol. FILENAME is a string naming a file containing Scheme source code. The procedure `add-source' registers FEATURE so that the first time `require' is called with the symbol FEATURE as its argument, the file FILENAME will be `load'ed. An unspecified value is returned. Remember to delete the file `slibcat' after modifying the file `mkimpcat.scm' in order to force SLIB to rebuild its cache.  File: scm.info, Node: Saving Images, Next: Automatic C Preprocessor Definitions, Prev: Configure Module Catalog, Up: Installing SCM Saving Images ============= In SCM, the ability to save running program images is called "dump" (*note Dump::). In order to make `dump' available to SCM, build with feature `dump'. `dump'ed executables are compatible with dynamic linking. Most of the code for "dump" is taken from `emacs-19.34/src/unex*.c'. No modifications to the emacs source code were required to use `unexelf.c'. Dump has not been ported to all platforms. If `unexec.c' or `unexelf.c' don't work for you, try using the appropriate `unex*.c' file from emacs.  File: scm.info, Node: Automatic C Preprocessor Definitions, Next: Problems Compiling, Prev: Saving Images, Up: Installing SCM Automatic C Preprocessor Definitions ==================================== These `#defines' are automatically provided by preprocessors of various C compilers. SCM uses the presence or absence of these definitions to configure "include file" locations and aliases for library functions. If the definition(s) corresponding to your system type is missing as your system is configured, add `-DFLAG' to the compilation command lines or add a `#define FLAG' line to `scmfig.h' or the beginning of `scmfig.h'. #define Platforms: ------- ---------- ARM_ULIB Huw Rogers free unix library for acorn archimedes AZTEC_C Aztec_C 5.2a __CYGWIN__ Cygwin _DCC Dice C on AMIGA __GNUC__ Gnu CC (and DJGPP) __EMX__ Gnu C port (gcc/emx 0.8e) to OS/2 2.0 __HIGHC__ MetaWare High C __IBMC__ C-Set++ on OS/2 2.1 _MSC_VER MS VisualC++ 4.2 MWC Mark Williams C on COHERENT __MWERKS__ Metrowerks Compiler; Macintosh and WIN32 (?) _POSIX_SOURCE ?? _QC Microsoft QuickC __STDC__ ANSI C compliant __TURBOC__ Turbo C and Borland C __USE_POSIX ?? __WATCOMC__ Watcom C on MS-DOS __ZTC__ Zortech C _AIX AIX operating system __APPLE__ Apple Darwin AMIGA SAS/C 5.10 or Dice C on AMIGA __amigaos__ Gnu CC on AMIGA atarist ATARI-ST under Gnu CC __FreeBSD__ FreeBSD GNUDOS DJGPP (obsolete in version 1.08) __GO32__ DJGPP (future?) hpux HP-UX linux Linux macintosh Macintosh (THINK_C and __MWERKS__ define) MCH_AMIGA Aztec_c 5.2a on AMIGA __MACH__ Apple Darwin MSDOS Microsoft C 5.10 and 6.00A __MSDOS__ Turbo C, Borland C, and DJGPP nosve Control Data NOS/VE SVR2 System V Revision 2. __SVR4 SunOS THINK_C developement environment for the Macintosh ultrix VAX with ULTRIX operating system. unix most Unix and similar systems and DJGPP (!?) __unix__ Gnu CC and DJGPP _UNICOS Cray operating system vaxc VAX C compiler VAXC VAX C compiler vax11c VAX C compiler VAX11 VAX C compiler _Windows Borland C 3.1 compiling for Windows _WIN32 MS VisualC++ 4.2 and Cygwin (Win32 API) vms (and VMS) VAX-11 C under VMS. __alpha DEC Alpha processor __alpha__ DEC Alpha processor hp9000s800 HP RISC processor __i386__ DJGPP i386 DJGPP MULTIMAX Encore computer ppc PowerPC __ppc__ PowerPC pyr Pyramid 9810 processor __sgi__ Silicon Graphics Inc. sparc SPARC processor sequent Sequent computer tahoe CCI Tahoe processor vax VAX processor  File: scm.info, Node: Problems Compiling, Next: Problems Linking, Prev: Automatic C Preprocessor Definitions, Up: Installing SCM Problems Compiling ================== FILE PROBLEM / MESSAGE HOW TO FIX *.c include file not found. Correct the status of STDC_HEADERS in scmfig.h. fix #include statement or add #define for system type to scmfig.h. *.c Function should return a value. Ignore. Parameter is never used. Condition is always false. Unreachable code in function. scm.c assignment between incompatible Change SIGRETTYPE in scm.c. types. time.c CLK_TCK redefined. incompatablility between and . Remove STDC_HEADERS in scmfig.h. Edit to remove incompatability. subr.c Possibly incorrect assignment Ignore. in function lgcd. sys.c statement not reached. Ignore. constant in conditional expression. sys.c undeclared, outside of #undef STDC_HEADERS in scmfig.h. functions. scl.c syntax error. #define SYSTNAME to your system type in scl.c (softtype).  File: scm.info, Node: Problems Linking, Next: Problems Running, Prev: Problems Compiling, Up: Installing SCM Problems Linking ================ PROBLEM HOW TO FIX _sin etc. missing. Uncomment LIBS in makefile.  File: scm.info, Node: Problems Running, Next: Testing, Prev: Problems Linking, Up: Installing SCM Problems Running ================ PROBLEM HOW TO FIX Opening message and then machine Change memory model option to C crashes. compiler (or makefile). Make sure sizet definition is correct in scmfig.h. Reduce the size of HEAP_SEG_SIZE in setjump.h. Input hangs. #define NOSETBUF ERROR: heap: need larger initial. Increase initial heap allocation using -a or INIT_HEAP_SIZE. ERROR: Could not allocate. Check sizet definition. Use 32 bit compiler mode. Don't try to run as subproccess. remove in scmfig.h and Do so and recompile files. recompile scm. add in scmfig.h and recompile scm. ERROR: Init5d6.scm not found. Assign correct IMPLINIT in makefile or scmfig.h. Define environment variable SCM_INIT_PATH to be the full pathname of Init5d6.scm. WARNING: require.scm not found. Define environment variable SCHEME_LIBRARY_PATH to be the full pathname of the scheme library [SLIB]. Change library-vicinity in Init5d6.scm to point to library or remove. Make sure the value of (library-vicinity) has a trailing file separator (like / or \).  File: scm.info, Node: Testing, Next: Reporting Problems, Prev: Problems Running, Up: Installing SCM Testing ======= Loading `r4rstest.scm' in the distribution will run an [R4RS] conformance test on `scm'. > (load "r4rstest.scm") -| ;loading "r4rstest.scm" SECTION(2 1) SECTION(3 4) # # # # ... Loading `pi.scm' in the distribution will enable you to compute digits of pi. > (load "pi") ;loading "pi" ;done loading "pi.scm" ;Evaluation took 20 ms (0 in gc) 767 cells work, 233.B other # > (pi 100 5) 00003 14159 26535 89793 23846 26433 83279 50288 41971 69399 37510 58209 74944 59230 78164 06286 20899 86280 34825 34211 70679 ;Evaluation took 550 ms (60 in gc) 36976 cells work, 1548.B other # Loading `bench.scm' will compute and display performance statistics of SCM running `pi.scm'. `make bench' or `make benchlit' appends the performance report to the file `BenchLog', facilitating tracking effects of changes to SCM on performance. PROBLEM HOW TO FIX Runs some and then machine crashes. See above under machine crashes. Runs some and then ERROR: ... Remove optimization option to C (after a GC has happened). compiler and recompile. #define SHORT_ALIGN in `scmfig.h'. Some symbol names print incorrectly. Change memory model option to C compiler (or makefile). Check that HEAP_SEG_SIZE fits within sizet. Increase size of HEAP_SEG_SIZE (or INIT_HEAP_SIZE if it is smaller than HEAP_SEG_SIZE). ERROR: Rogue pointer in Heap. See above under machine crashes. Newlines don't appear correctly in Check file mode (define OPEN_... in output files. `Init5d6.scm'). Spaces or control characters appear Check character defines in in symbol names. `scmfig.h'. Negative numbers turn positive. Check SRS in `scmfig.h'. VMS: Couldn't unwind stack. #define CHEAP_CONTIUATIONS in `scmfig.h'. VAX: botched longjmp. Sparc(SUN-4) heap is growing out of control You are experiencing a GC problem peculiar to the Sparc. The problem is that SCM doesn't know how to clear register windows. Every location which is not reused still gets marked at GC time. This causes lots of stuff which should be collected to not be. This will be a problem with any _conservative_ GC until we find what instruction will clear the register windows. This problem is exacerbated by using lots of call-with-current-continuations.  File: scm.info, Node: Reporting Problems, Prev: Testing, Up: Installing SCM Reporting Problems ================== Reported problems and solutions are grouped under Compiling, Linking, Running, and Testing. If you don't find your problem listed there, you can send a bug report to `jaffer @ alum.mit.edu'. The bug report should include: 1. The version of SCM (printed when SCM is invoked with no arguments). 2. The type of computer you are using. 3. The name and version of your computer's operating system. 4. The values of the environment variables `SCM_INIT_PATH' and `SCHEME_LIBRARY_PATH'. 5. The name and version of your C compiler. 6. If you are using an executable from a distribution, the name, vendor, and date of that distribution. In this case, corresponding with the vendor is recommended.  File: scm.info, Node: Operational Features, Next: The Language, Prev: Installing SCM, Up: Top Operational Features ******************** * Menu: * Invoking SCM:: * SCM Options:: * Invocation Examples:: * SCM Variables:: * SCM Session:: * Editing Scheme Code:: * Debugging Scheme Code:: * Errors:: * Memoized Expressions:: * Internal State:: * Scripting::  File: scm.info, Node: Invoking SCM, Next: SCM Options, Prev: Operational Features, Up: Operational Features Invoking SCM ============ scm [-a kbytes] [-muvbiq] [-version] [-help] [[-]-no-init-file] [-p int] [-r feature] [-h feature] [-d filename] [-f filename] [-l filename] [-c expression] [-e expression] [-o dumpname] [-- | - | -s] [filename] [arguments ...] Upon startup `scm' loads the file specified by by the environment variable SCM_INIT_PATH. If SCM_INIT_PATH is not defined or if the file it names is not present, `scm' tries to find the directory containing the executable file. If it is able to locate the executable, `scm' looks for the initialization file (usually `Init5d6.scm') in platform-dependent directories relative to this directory. See *Note File-System Habitat:: for a blow-by-blow description. As a last resort (if initialization file cannot be located), the C compile parameter IMPLINIT (defined in the makefile or `scmfig.h') is tried. Unless the option `-no-init-file' or `--no-init-file' occurs in the command line, `Init5d6.scm' checks to see if there is file `ScmInit.scm' in the path specified by the environment variable HOME (or in the current directory if HOME is undefined). If it finds such a file it is loaded. `Init5d6.scm' then looks for command input from one of three sources: From an option on the command line, from a file named on the command line, or from standard input. This explanation applies to SCMLIT or other builds of SCM. Scheme-code files can also invoke SCM and its variants. *Note #!: Syntax Extensions.  File: scm.info, Node: SCM Options, Next: Invocation Examples, Prev: Invoking SCM, Up: Operational Features Options ======= The options are processed in the order specified on the command line. - Command Option: -a k specifies that `scm' should allocate an initial heapsize of K kilobytes. This option, if present, must be the first on the command line. If not specified, the default is `INIT_HEAP_SIZE' in source file `setjump.h' which the distribution sets at `25000*sizeof(cell)'. - Command Option: -no-init-file - Command Option: --no-init-file Inhibits the loading of `ScmInit.scm' as described above. - Command Option: --help prints usage information and URI; then exit. - Command Option: --version prints version information and exit. - Command Option: -r feature requires FEATURE. This will load a file from [SLIB] if that FEATURE is not already provided. If FEATURE is 2, 2rs, r2rs, 3, 3rs, r3rs, 4, 4rs, r4rs, 5, 5rs, or r5rs; `scm' will require the features neccessary to support [R2RS], [R3RS], [R4RS], or [R5RS], respectively. - Command Option: -h feature provides FEATURE. - Command Option: -l filename - Command Option: -f filename loads FILENAME. `Scm' will load the first (unoptioned) file named on the command line if no `-c', `-e', `-f', `-l', or `-s' option preceeds it. - Command Option: -d filename Loads SLIB `databases' feature and opens FILENAME as a database. - Command Option: -e expression - Command Option: -c expression specifies that the scheme expression EXPRESSION is to be evaluated. These options are inspired by `perl' and `sh' respectively. On Amiga systems the entire option and argument need to be enclosed in quotes. For instance `"-e(newline)"'. - Command Option: -o dumpname saves the current SCM session as the executable program `dumpname'. This option works only in SCM builds supporting `dump' (*note Dump::). If options appear on the command line after `-o DUMPNAME', then the saved session will continue with processing those options when it is invoked. Otherwise the (new) command line is processed as usual when the saved image is invoked. - Command Option: -p level sets the prolixity (verboseness) to LEVEL. This is the same as the `scm' command (verobse LEVEL). - Command Option: -v (verbose mode) specifies that `scm' will print prompts, evaluation times, notice of loading files, and garbage collection statistics. This is the same as `-p3'. - Command Option: -q (quiet mode) specifies that `scm' will print no extra information. This is the same as `-p0'. - Command Option: -m specifies that subsequent loads, evaluations, and user interactions will be with syntax-rules macro capability. To use a specific syntax-rules macro implementation from [SLIB] (instead of [SLIB]'s default) put `-r' MACROPACKAGE before `-m' on the command line. - Command Option: -u specifies that subsequent loads, evaluations, and user interactions will be without syntax-rules macro capability. Syntax-rules macro capability can be restored by a subsequent `-m' on the command line or from Scheme code. - Command Option: -i specifies that `scm' should run interactively. That means that `scm' will not terminate until the `(quit)' or `(exit)' command is given, even if there are errors. It also sets the prolixity level to 2 if it is less than 2. This will print prompts, evaluation times, and notice of loading files. The prolixity level can be set by subsequent options. If `scm' is started from a tty, it will assume that it should be interactive unless given a subsequent `-b' option. - Command Option: -b specifies that `scm' should run non-interactively. That means that `scm' will terminate after processing the command line or if there are errors. - Command Option: -s specifies, by analogy with `sh', that further options are to be treated as program aguments. - Command Option: - - Command Option: -- specifies that there are no more options on the command line.  File: scm.info, Node: Invocation Examples, Next: SCM Variables, Prev: SCM Options, Up: Operational Features Invocation Examples =================== `% scm foo.scm' Loads and executes the contents of `foo.scm' and then enters interactive session. `% scm -f foo.scm arg1 arg2 arg3' Parameters `arg1', `arg2', and `arg3' are stored in the global list `*argv*'; Loads and executes the contents of `foo.scm' and exits. `% scm -s foo.scm arg1 arg2' Sets *argv* to `("foo.scm" "arg1" "arg2")' and enters interactive session. `% scm -e `(write (list-ref *argv* *optind*))' bar' Prints `"bar"'. `% scm -rpretty-print -r format -i' Loads `pretty-print' and `format' and enters interactive session. `% scm -r5' Loads `dynamic-wind', `values', and syntax-rules macros and enters interactive (with macros) session. `% scm -r5 -r4' Like above but `rev4-optional-procedures' are also loaded.  File: scm.info, Node: SCM Variables, Next: SCM Session, Prev: Invocation Examples, Up: Operational Features Environment Variables ===================== - Environment Variable: SCM_INIT_PATH is the pathname where `scm' will look for its initialization code. The default is the file `Init5d6.scm' in the source directory. - Environment Variable: SCHEME_LIBRARY_PATH is the [SLIB] Scheme library directory. - Environment Variable: HOME is the directory where `Init5d6.scm' will look for the user initialization file `ScmInit.scm'. - Environment Variable: EDITOR is the name of the program which `ed' will call. If EDITOR is not defined, the default is `ed'. Scheme Variables ================ - Variable: *argv* contains the list of arguments to the program. `*argv*' can change during argument processing. This list is suitable for use as an argument to [SLIB] `getopt'. - Variable: *syntax-rules* controls whether loading and interaction support syntax-rules macros. Define this in `ScmInit.scm' or files specified on the command line. This can be overridden by subsequent `-m' and `-u' options. - Variable: *interactive* controls interactivity as explained for the `-i' and `-b' options. Define this in `ScmInit.scm' or files specified on the command line. This can be overridden by subsequent `-i' and `-b' options.  File: scm.info, Node: SCM Session, Next: Editing Scheme Code, Prev: SCM Variables, Up: Operational Features SCM Session =========== * Options, file loading and features can be specified from the command line. *Note System interface: (scm)System interface. *Note Require: (slib)Require. * Typing the end-of-file character at the top level session (while SCM is not waiting for parenthesis closure) causes SCM to exit. * Typing the interrupt character aborts evaluation of the current form and resumes the top level read-eval-print loop. - Function: quit - Function: quit n - Function: exit - Function: exit n Aliases for `exit' (*note exit: (slib)System.). On many systems, SCM can also tail-call another program. *Note execp: I/O-Extensions. - Callback procedure: boot-tail dumped? `boot-tail' is called by `scm_top_level' just before entering interactive top-level. If `boot-tail' calls `quit', then interactive top-level is not entered. - Function: program-arguments Returns a list of strings of the arguments scm was called with. For documentation of the procedures `getenv' and `system' *Note System Interface: (slib)System Interface. - Function: vms-debug If SCM is compiled under VMS this `vms-debug' will invoke the VMS debugger.  File: scm.info, Node: Editing Scheme Code, Next: Debugging Scheme Code, Prev: SCM Session, Up: Operational Features Editing Scheme Code =================== - Function: ed arg1 ... The value of the environment variable `EDITOR' (or just `ed' if it isn't defined) is invoked as a command with arguments ARG1 .... - Function: ed filename If SCM is compiled under VMS `ed' will invoke the editor with a single the single argument FILENAME. Gnu Emacs: Editing of Scheme code is supported by emacs. Buffers holding files ending in .scm are automatically put into scheme-mode. EMACS for MS-DOS and MS-Windows systems is available (free) from: If your Emacs can run a process in a buffer you can use the Emacs command `M-x run-scheme' with SCM. Otherwise, use the emacs command `M-x suspend-emacs'; or see "other systems" below. Epsilon (MS-DOS): There is lisp (and scheme) mode available by use of the package `LISP.E'. It offers several different indentation formats. With this package, buffers holding files ending in `.L', `.LSP', `.S', and `.SCM' (my modification) are automatically put into lisp-mode. It is possible to run a process in a buffer under Epsilon. With Epsilon 5.0 the command line options `-e512 -m0' are neccessary to manage RAM properly. It has been reported that when compiling SCM with Turbo C, you need to `#define NOSETBUF' for proper operation in a process buffer with Epsilon 5.0. One can also call out to an editor from SCM if RAM is at a premium; See "under other systems" below. other systems: Define the environment variable `EDITOR' to be the name of the editing program you use. The SCM procedure `(ed arg1 ...)' will invoke your editor and return to SCM when you exit the editor. The following definition is convenient: (define (e) (ed "work.scm") (load "work.scm")) Typing `(e)' will invoke the editor with the file of interest. After editing, the modified file will be loaded.  File: scm.info, Node: Debugging Scheme Code, Next: Errors, Prev: Editing Scheme Code, Up: Operational Features Debugging Scheme Code ===================== The `cautious' and `stack-limit' options of `build' (*note Build Options::) support debugging in Scheme. "CAUTIOUS" If SCM is built with the `CAUTIOUS' flag, then when an error occurs, a "stack trace" of certain pending calls are printed as part of the default error response. A (memoized) expression and newline are printed for each partially evaluated combination whose procedure is not builtin. See *Note Memoized Expressions:: for how to read memoized expressions. Also as the result of the `CAUTIOUS' flag, both `error' and `user-interrupt' (invoked by ) to print stack traces and conclude by calling `breakpoint' (*note Breakpoints: (slib)Breakpoints.) instead of aborting to top level. Under either condition, program execution can be resumed by `(continue)'. In this configuration one can interrupt a running Scheme program with , inspect or modify top-level values, trace or untrace procedures, and continue execution with `(continue)'. "STACK_LIMIT" If SCM is built with the `STACK_LIMIT' flag, the interpreter will check stack size periodically. If the size of stack exceeds a certain amount (default is `HEAP_SEG_SIZE/2'), SCM generates a `segment violation' interrupt. The usefulness of `STACK_LIMIT' depends on the user. I don't use it; but the user I added this feature for got primarily this type of error. There are several SLIB macros which so useful that SCM automatically loads the appropriate module from SLIB if they are invoked. - Macro: trace proc1 ... Traces the top-level named procedures given as arguments. - Macro: trace 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. - Macro: untrace proc1 ... Turns tracing off for its arguments. - Macro: untrace With no arguments, untraces all currently traced identifiers and returns a list of these formerly traced identifiers. The routines I use most frequently for debugging are: - Procedure: print arg1 ... `Print' writes all its arguments, separated by spaces. `Print' outputs a `newline' at the end and returns the value of the last argument. One can just insert `(print '' and `)' around an expression in order to see its value as a program operates. - Syntax: print-args name1 ... Writes NAME1 ... (separated by spaces) and then writes the values of the closest lexical bindings enclosing the call to `Print-args'. (define (foo a b) (print-args foo) (+ a b)) (foo 3 6) -| In foo: a = 3; b = 6; => 9 Sometimes more elaborate measures are needed to print values in a useful manner. When the values to be printed may have very large (or infinite) external representations, *Note Quick Print: (slib)Quick Print, can be used. When `trace' is not sufficient to find program flow problems, SLIB-PSD, the Portable Scheme Debugger offers source code debugging from GNU Emacs. PSD runs slowly, so start by instrumenting only a few functions at a time. http://swissnet.ai.mit.edu/ftpdir/scm/slib-psd1-3.tar.gz swissnet.ai.mit.edu:/pub/scm/slib-psd1-3.tar.gz ftp.maths.tcd.ie:pub/bosullvn/jacal/slib-psd1-3.tar.gz ftp.cs.indiana.edu:/pub/scheme-repository/utl/slib-psd1-3.tar.gz  File: scm.info, Node: Errors, Next: Memoized Expressions, Prev: Debugging Scheme Code, Up: Operational Features Errors ====== A computer-language implementation designer faces choices of how reflexive to make the implementation in handling exceptions and errors; that is, how much of the error and exception routines should be written in the language itself. The design of a portable implementation is further constrained by the need to have (almost) all errors print meaningful messages, even when the implementation itself is not functioning correctly. Therefore, SCM implements much of its error response code in C. The following common error and conditions are handled by C code. Those with callback names after them can also be handled by Scheme code (*note Interrupts::). If the callback identifier is not defined at top level, the default error handler (C code) is invoked. There are many other error messages which are not treated specially. "ARGn" Wrong type in argument "ARG1" Wrong type in argument 1 "ARG2" Wrong type in argument 2 "ARG3" Wrong type in argument 3 "ARG4" Wrong type in argument 4 "ARG5" Wrong type in argument 5 "WNA" Wrong number of args "OVFLOW" numerical overflow "OUTOFRANGE" Argument out of range "NALLOC" `(out-of-storage)' "THRASH" GC is `(thrashing)' "EXIT" `(end-of-program)' "HUP_SIGNAL" `(hang-up)' "INT_SIGNAL" `(user-interrupt)' "FPE_SIGNAL" `(arithmetic-error)' "BUS_SIGNAL" bus error "SEGV_SIGNAL" segment violation "ALRM_SIGNAL" `(alarm-interrupt)' "VTALRM_SIGNAL" `(virtual-alarm-interrupt)' "PROF_SIGNAL" `(profile-alarm-interrupt)' - Variable: errobj When SCM encounters a non-fatal error, it aborts evaluation of the current form, prints a message explaining the error, and resumes the top level read-eval-print loop. The value of ERROBJ is the offending object if appropriate. The builtin procedure `error' does _not_ set ERROBJ. `errno' and `perror' report ANSI C errors encountered during a call to a system or library function. - Function: errno - Function: errno n With no argument returns the current value of the system variable `errno'. When given an argument, `errno' sets the system variable `errno' to N and returns the previous value of `errno'. `(errno 0)' will clear outstanding errors. This is recommended after `try-load' returns `#f' since this occurs when the file could not be opened. - Function: perror string Prints on standard error output the argument STRING, a colon, followed by a space, the error message corresponding to the current value of `errno' and a newline. The value returned is unspecified. `warn' and `error' provide a uniform way for Scheme code to signal warnings and errors. - Function: warn arg1 arg2 arg3 ... Alias for *Note slib:warn: (slib)System. Outputs an error message containing the arguments. `warn' is defined in `Init5d6.scm'. - Function: error arg1 arg2 arg3 ... Alias for *Note slib:error: (slib)System. Outputs an error message containing the arguments, aborts evaluation of the current form and resumes the top level read-eval-print loop. `Error' is defined in `Init5d6.scm'. If SCM is built with the `CAUTIOUS' flag, then when an error occurs, a "stack trace" of certain pending calls are printed as part of the default error response. A (memoized) expression and newline are printed for each partially evaluated combination whose procedure is not builtin. See *Note Memoized Expressions:: for how to read memoized expressions. Also as the result of the `CAUTIOUS' flag, both `error' and `user-interrupt' (invoked by ) are defined to print stack traces and conclude by calling `breakpoint' (*note Breakpoints: (slib)Breakpoints.). This allows the user to interract with SCM as with Lisp systems. - Function: stack-trace Prints information describing the stack of partially evaluated expressions. `stack-trace' returns `#t' if any lines were printed and `#f' otherwise. See `Init5d6.scm' for an example of the use of `stack-trace'.  File: scm.info, Node: Memoized Expressions, Next: Internal State, Prev: Errors, Up: Operational Features Memoized Expressions ==================== SCM memoizes the address of each occurence of an identifier's value when first encountering it in a source expression. Subsequent executions of that memoized expression is faster because the memoized reference encodes where in the top-level or local environment its value is. When procedures are displayed, the memoized locations appear in a format different from references which have not yet been executed. I find this a convenient aid to locating bugs and untested expressions. * The names of memoized lexically bound identifiers are replaced with #@-, where is the number of binding contours back and is the index of the value in that binding countour. * The names of identifiers which are not lexiallly bound but defined at top-level have #@ prepended. For instance, `open-input-file' is defined as follows in `Init5d6.scm': (define (open-input-file str) (or (open-file str OPEN_READ) (and (procedure? could-not-open) (could-not-open) #f) (error "OPEN-INPUT-FILE couldn't open file " str))) If `open-input-file' has not yet been used, the displayed procedure is similar to the original definition (lines wrapped for readability): open-input-file => # If we open a file using `open-input-file', the sections of code used become memoized: (open-input-file "r4rstest.scm") => # open-input-file => # If we cause `open-input-file' to execute other sections of code, they too become memoized: (open-input-file "foo.scm") => ERROR: No such file or directory ERROR: OPEN-INPUT-FILE couldn't open file "foo.scm" open-input-file => #  File: scm.info, Node: Internal State, Next: Scripting, Prev: Memoized Expressions, Up: Operational Features Internal State ============== - Variable: *interactive* The variable *INTERACTIVE* determines whether the SCM session is interactive, or should quit after the command line is processed. *INTERACTIVE* is controlled directly by the command-line options `-b', `-i', and `-s' (*note Invoking SCM::). If none of these options are specified, the rules to determine interactivity are more complicated; see `Init5d6.scm' for details. - Function: abort Resumes the top level Read-Eval-Print loop. - Function: restart Restarts the SCM program with the same arguments as it was originally invoked. All `-l' loaded files are loaded again; If those files have changed, those changes will be reflected in the new session. _Note:_ When running a saved executable (*note Dump::), `restart' is redefined to be `exec-self'. - Function: exec-self Exits and immediately re-invokes the same executable with the same arguments. If the executable file has been changed or replaced since the beginning of the current session, the _new_ executable will be invoked. This differentiates `exec-self' from `restart'. - Function: verbose n Controls how much monitoring information is printed. If N is: 0 no prompt or information is printed. >= 1 a prompt is printed. >= 2 messages bracketing file loading are printed. >= 3 the CPU time is printed after each top level form evaluated; notifications of heap growth printed. >= 4 a garbage collection summary is printed after each top level form evaluated; >= 5 a message for each GC (*note Garbage Collection::) is printed; warnings issued for top-level symbols redefined. - Function: gc Scans all of SCM objects and reclaims for further use those that are no longer accessible. - Function: room - Function: room #t Prints out statistics about SCM's current use of storage. `(room #t)' also gives the hexadecimal heap segment and stack bounds. - Constant: *scm-version* Contains the version string (e.g. `5d6') of SCM. Executable path --------------- In order to dump a saved executable or to dynamically-link using DLD, SCM must know where its executable file is. Sometimes SCM (*note Executable Pathname::) guesses incorrectly the location of the currently running executable. In that case, the correct path can be set by calling `execpath' with the pathname. - Function: execpath Returns the path (string) which SCM uses to find the executable file whose invocation the currently running session is, or #f if the path is not set. - Function: execpath #f - Function: execpath newpath Sets the path to `#f' or NEWPATH, respectively. The old path is returned. For other configuration constants and procedures *Note Configuration: (slib)Configuration.  File: scm.info, Node: Scripting, Prev: Internal State, Up: Operational Features Scripting ========= * Menu: * Unix Scheme Scripts:: From Olin Shivers' Scheme Shell * MS-DOS Compatible Scripts:: Run in MS-DOS and Unix * Unix Shell Scripts:: Use /bin/sh to run Scheme  File: scm.info, Node: Unix Scheme Scripts, Next: MS-DOS Compatible Scripts, Prev: Scripting, Up: Scripting Unix Scheme Scripts ------------------- In reading this section, keep in mind that the first line of a script file has (different) meanings to SCM and the operating system (`execve'). - file: #! interpreter \ ... On unix systems, a "Shell-Script" is a file (with execute permissions) whose first two characters are `#!'. The INTERPRETER argument must be the pathname of the program to process the rest of the file. The directories named by environment variable `PATH' are _not_ searched to find INTERPRETER. When executing a shell-script, the operating system invokes INTERPRETER with a single argument encapsulating the rest of the first line's contents (if if not just whitespace), the pathname of the Scheme Script file, and then any arguments which the shell-script was invoked with. Put one space character between `#!' and the first character of INTERPRETER (`/'). The INTERPRETER name is followed by ` \'; SCM substitutes the second line of FILE for `\' (and the rest of the line), then appends any arguments given on the command line invoking this Scheme-Script. When SCM executes the script, the Scheme variable *SCRIPT* will be set to the script pathname. The last argument before `!#' on the second line should be `-'; SCM will load the script file, preserve the unprocessed arguments, and set *ARGV* to a list of the script pathname and the unprocessed arguments. Note that the interpreter, not the operating system, provides the `\' substitution; this will only take place if INTERPRETER is a SCM or SCSH interpreter. - Read syntax: #! ignored !# When the first two characters of the file being loaded are `#!' and a `\' is present before a newline in the file, all characters up to `!#' will be ignored by SCM `read'. This combination of interpretatons allows SCM source files to be used as POSIX shell-scripts if the first line is: #! /usr/local/bin/scm \ The following Scheme-Script prints factorial of its argument: #! /usr/local/bin/scm \ %0 %1 %2 %3 %4 %5 %6 %7 %8 %9 - !# ; -*-scheme-*- (define (go-script) (cond ((not *script*)) ((and (= 1 (- (length *argv*) *optind*)) (string->number (list-ref *argv* *optind*))) => (lambda (n) (print (fact n)))) (else (print *argv*) (display "\ Usage: fact n Returns the factorial of N. http://swissnet.ai.mit.edu/~jaffer/SLIB.html " (current-error-port)) (exit #f)))) (define (fact n) (if (< n 2) 1 (* n (fact (+ -1 n))))) (go-script) ./fact 32 => 263130836933693530167218012160000000 If the wrong number of arguments is given, `fact' prints its ARGV with usage information. ./fact 3 2 -| ("./fact" "3" "2") Usage: fact n Returns the factorial of N. http://swissnet.ai.mit.edu/~jaffer/SLIB.html  File: scm.info, Node: MS-DOS Compatible Scripts, Next: Unix Shell Scripts, Prev: Unix Scheme Scripts, Up: Scripting MS-DOS Compatible Scripts ------------------------- It turns out that we can create scheme-scripts which run both under unix and MS-DOS. To implement this, I have written the MS-DOS programs: `#!.bat' and `!#.exe'. With these two programs installed in a `PATH' directory, we have the following syntax for .BAT files. - file: #! interpreter \ %0 %1 %2 %3 %4 %5 %6 %7 %8 %9 The first two characters of the Scheme-Script are `#!'. The INTERPRETER can be either a unix style program path (using `/' between filename components) or a DOS program name or path. The rest of the first line of the Scheme-Script should be literally `\ %0 %1 %2 %3 %4 %5 %6 %7 %8 %9', as shown. If INTERPRETER has `/' in it, INTERPRETER is converted to a DOS style filename (`/' => `\'). In looking for an executable named INTERPRETER, `#!' first checks this (converted) filename; if INTERPRETER doesn't exist, it then tries to find a program named like the string starting after the last `\' (or `/') in INTERPRETER. When searching for executables, `#!' tries all directories named by environment variable `PATH'. Once the INTERPRETER executable path is found, arguments are processed in the manner of scheme-shell, with the all the text after the `\' taken as part of the meta-argument. More precisely, `#!' calls INTERPRETER with any options on the second line of the Scheme-Script up to `!#', the name of the Scheme-Script file, and then any of at most 8 arguments given on the command line invoking this Scheme-Script. The previous example Scheme-Script works in both MS-DOS and unix systems.  File: scm.info, Node: Unix Shell Scripts, Prev: MS-DOS Compatible Scripts, Up: Scripting Unix Shell Scripts ------------------ Scheme-scripts suffer from two drawbacks: * Some Unixes limit the length of the `#!' interpreter line to the size of an object file header, which can be as small as 32 bytes. * A full, explicit pathname must be specified, perhaps requiring more than 32 bytes and making scripts vulnerable to breakage when programs are moved. The following approach solves these problems at the expense of slower startup. Make `#! /bin/sh' the first line and prepend every subsequent line to be executed by the shell with `:;'. The last line to be executed by the shell should contain an "exec" command; `exec' tail-calls its argument. `/bin/sh' is thus invoked with the name of the script file, which it executes as a *sh script. Usually the second line starts `:;exec scm -f$0', which executes scm, which in turn loads the script file. When SCM loads the script file, it ignores the first and second lines, and evaluates the rest of the file as Scheme source code. The second line of the script file does not have the length restriction mentioned above. Also, `/bin/sh' searches the directories listed in the `PATH' environment variable for `scm', eliminating the need to use absolute locations in order to invoke a program. The following example additionally sets *SCRIPT* to the script argument, making it compatible with the scheme code of the previous example. #! /bin/sh :;exec scm -e"(set! *script* \"$0\")" -l$0 $* (define (go-script) (cond ((not *script*)) ((and (= 1 (- (length *argv*) *optind*)) (string->number (list-ref *argv* *optind*))) => (lambda (n) (print (fact n)))) (else (print *argv*) (display "\ Usage: fact n Returns the factorial of N. http://swissnet.ai.mit.edu/~jaffer/SLIB.html " (current-error-port)) (exit #f)))) (define (fact n) (if (< n 2) 1 (* n (fact (+ -1 n))))) (go-script) ./fact 6 => 720  File: scm.info, Node: The Language, Next: Packages, Prev: Operational Features, Up: Top The Language ************ * Menu: * Standards Compliance:: Links to sections in [R5RS] and [SLIB] * Miscellaneous Procedures:: * Time:: Both real time and processor time * Interrupts:: and exceptions * Process Synchronization:: Because interrupts are preemptive * Files and Ports:: * Line Numbers:: * Soft Ports:: Emulate I/O devices * Syntax Extensions:: * Low Level Syntactic Hooks:: * Syntactic Hooks for Hygienic Macros::  File: scm.info, Node: Standards Compliance, Next: Miscellaneous Procedures, Prev: The Language, Up: The Language Standards Compliance ==================== Scm conforms to the `IEEE Standard 1178-1990. IEEE Standard for the Scheme Programming Language.' (*note Bibliography::), and `Revised(5) Report on the Algorithmic Language Scheme'. *Note Top: (r5rs)Top. All the required features of these specifications are supported. Many of the optional features are supported as well. Optionals of [R5RS] Supported by SCM ------------------------------------ `-' and `/' of more than 2 arguments `exp' `log' `sin' `cos' `tan' `asin' `acos' `atan' `sqrt' `expt' `make-rectangular' `make-polar' `real-part' `imag-part' `magnitude' `angle' `exact->inexact' `inexact->exact' *Note Numerical operations: (r5rs)Numerical operations. `with-input-from-file' `with-output-to-file' *Note Ports: (r5rs)Ports. `load' `transcript-on' `transcript-off' *Note System interface: (r5rs)System interface. Optionals of [R5RS] not Supported by SCM ---------------------------------------- `numerator' `denominator' `rationalize' *Note Numerical operations: (r5rs)Numerical operations. [SLIB] Features of SCM and SCMLIT --------------------------------- `delay' `full-continuation' `ieee-p1178' `object-hash' `rev4-report' `source' See SLIB file `Template.scm'. `current-time' *Note Time: (slib)Time. `defmacro' *Note Defmacro: (slib)Defmacro. `getenv' `system' *Note System Interface: (slib)System Interface. `hash' *Note Hashing: (slib)Hashing. `logical' *Note Bit-Twiddling: (slib)Bit-Twiddling. `multiarg-apply' *Note Multi-argument Apply: (slib)Multi-argument Apply. `multiarg/and-' *Note Multi-argument / and -: (slib)Multi-argument / and -. `rev4-optional-procedures' *Note Rev4 Optional Procedures: (slib)Rev4 Optional Procedures. `string-port' *Note String Ports: (slib)String Ports. `tmpnam' *Note Input/Output: (slib)Input/Output. `transcript' *Note Transcripts: (slib)Transcripts. `vicinity' *Note Vicinity: (slib)Vicinity. `with-file' *Note With-File: (slib)With-File. [SLIB] Features of SCM ---------------------- `array' *Note Arrays: (slib)Arrays. `array-for-each' *Note Array Mapping: (slib)Array Mapping. `bignum' `complex' `inexact' `rational' `real' *Note Require: (slib)Require.  File: scm.info, Node: Miscellaneous Procedures, Next: Time, Prev: Standards Compliance, Up: The Language Miscellaneous Procedures ======================== - Function: try-load filename If the string FILENAME names an existing file, the try-load procedure reads Scheme source code expressions and definitions from the file and evaluates them sequentially and returns `#t'. If not, try-load returns `#f'. The try-load procedure does not affect the values returned by `current-input-port' and `current-output-port'. - Variable: *load-pathname* Is set to the pathname given as argument to `load', `try-load', and `dyn:link' (*note Compiling And Linking: (hobbit)Compiling And Linking.). `*load-pathname*' is used to compute the value of *Note program-vicinity: (slib)Vicinity. - Function: line-number Returns the current line number of the file currently being loaded. - Function: port-filename port Returns the filename PORT was opened with. If PORT is not open to a file the result is unspecified. - Function: port-line port - Function: port-column port If PORT is a tracked port, return the current line (column) number, otherwise return `#f'. Line and column numbers begin with 1. The column number applies to the next character to be read; if that character is a newline, then the column number will be one more than the length of the line. - Function: eval obj Alias for *Note eval: (slib)System. - Function: eval-string str Returns the result of reading an expression from STR and evaluating it. `eval-string' does not change `*load-pathname*' or `line-number'. - Function: load-string str Reads and evaluates all the expressions from STR. As with `load', the value returned is unspecified. `load-string' does not change `*load-pathname*' or `line-number'. - Function: vector-set-length! object length Change the length of string, vector, bit-vector, or uniform-array OBJECT to LENGTH. If this shortens OBJECT then the remaining contents are lost. If it enlarges OBJECT then the contents of the extended part are undefined but the original part is unchanged. It is an error to change the length of literal datums. The new object is returned. - Function: copy-tree obj - Function: @copy-tree obj *Note copy-tree: (slib)Tree Operations. This extends the SLIB version by also copying vectors. Use `@copy-tree' if you depend on this feature; `copy-tree' could get redefined. - Function: acons obj1 obj2 obj3 Returns (cons (cons obj1 obj2) obj3). The expression (set! a-list (acons key datum a-list)) adds a new association to a-list. - Function: terms This command displays the GNU General Public License. - Function: list-file filename Displays the text contents of FILENAME. - Procedure: print arg1 ... `Print' writes all its arguments, separated by spaces. `Print' outputs a `newline' at the end and returns the value of the last argument.  File: scm.info, Node: Time, Next: Interrupts, Prev: Miscellaneous Procedures, Up: The Language Time ==== - Constant: internal-time-units-per-second Is the integer number of internal time units in a second. - Function: get-internal-run-time Returns the integer run time in internal time units from an unspecified starting time. The difference of two calls to `get-internal-run-time' divided by `internal-time-units-per-second' will give elapsed run time in seconds. - Function: get-internal-real-time Returns the integer time in internal time units from an unspecified starting time. The difference of two calls to `get-internal-real-time' divided by `interal-time-units-per-second' will give elapsed real time in seconds. - Function: current-time Returns the time since 00:00:00 GMT, January 1, 1970, measured in seconds. *Note current-time: (slib)Time. `current-time' is used in *Note Time: (slib)Time.  File: scm.info, Node: Interrupts, Next: Process Synchronization, Prev: Time, Up: The Language Interrupts ========== - Function: ticks n Returns the number of ticks remaining till the next tick interrupt. Ticks are an arbitrary unit of evaluation. Ticks can vary greatly in the amount of time they represent. If N is 0, any ticks request is canceled. Otherwise a `ticks-interrupt' will be signaled N from the current time. `ticks' is supported if SCM is compiled with the `ticks' flag defined. - Callback procedure: ticks-interrupt ... Establishes a response for tick interrupts. Another tick interrupt will not occur unless `ticks' is called again. Program execution will resume if the handler returns. This procedure should (abort) or some other action which does not return if it does not want processing to continue. - Function: alarm secs Returns the number of seconds remaining till the next alarm interrupt. If SECS is 0, any alarm request is canceled. Otherwise an `alarm-interrupt' will be signaled SECS from the current time. ALARM is not supported on all systems. - Function: milli-alarm millisecs interval - Function: virtual-alarm millisecs interval - Function: profile-alarm millisecs interval `milli-alarm' is similar to `alarm', except that the first argument MILLISECS, and the return value are measured in milliseconds rather than seconds. If the optional argument INTERVAL is supplied then alarm interrupts will be scheduled every INTERVAL milliseconds until turned off by a call to `milli-alarm' or `alarm'. `virtual-alarm' and `profile-alarm' are similar. `virtual-alarm' decrements process execution time rather than real time, and causes `SIGVTALRM' to be signaled. `profile-alarm' decrements both process execution time and system execution time on behalf of the process, and causes `SIGPROF' to be signaled. `milli-alarm', `virtual-alarm', and `profile-alarm' are supported only on systems providing the `setitimer' system call. - Callback procedure: user-interrupt ... - Callback procedure: alarm-interrupt ... - Callback procedure: virtual-alarm-interrupt ... - Callback procedure: profile-alarm-interrupt ... Establishes a response for `SIGINT' (control-C interrupt) and `SIGALRM', `SIGVTALRM', and `SIGPROF' interrupts. Program execution will resume if the handler returns. This procedure should `(abort)' or some other action which does not return if it does not want processing to continue after it returns. Interrupt handlers are disabled during execution `system' and `ed' procedures. To unestablish a response for an interrupt set the handler symbol to `#f'. For instance, `(set! user-interrupt #f)'. - Callback procedure: out-of-storage ... - Callback procedure: could-not-open ... - Callback procedure: end-of-program ... - Callback procedure: hang-up ... - Callback procedure: arithmetic-error ... Establishes a response for storage allocation error, file opening error, end of program, SIGHUP (hang up interrupt) and arithmetic errors respectively. This procedure should (abort) or some other action which does not return if it does not want the default error message to also be displayed. If no procedure is defined for HANG-UP then END-OF-PROGRAM (if defined) will be called. To unestablish a response for an error set the handler symbol to `#f'. For instance, `(set! could-not-open #f)'. - Callback procedure: gc-hook ... Allows a Scheme procedure to be run shortly after each garbage collection. This procedure will not be run recursively. If it runs long enough to cause a garbage collection before returning a warning will be printed. - Function: add-finalizer object finalizer OBJECT may be any garbage collected object, that is, any object other than an immediate integer, character, or special token such as `#f' or `#t', *Note Immediates::. FINALIZER is a thunk, or procedure taking no arguments. FINALIZER will be invoked asynchronously exactly once some time after OBJECT becomes eligible for garbage collection. A reference to OBJECT in the environment of FINALIZER will not prevent finalization, but will delay the reclamation of OBJECT at least until the next garbage collection. A reference to OBJECT in some other object's finalizer will necessarily prevent finalization until both objects are eligible for garbage collection. Finalizers are not run in any predictable order. All finalizers will be run by the time the program ends. This facility was based on the paper by Simon Peyton Jones, et al, "Stretching the storage manager: weak pointers and stable names in Haskell", Proc. 11th International Workshop on the Implementation of Functional Languages, The Netherlands, September 7-10 1999, Springer-Verlag LNCS.  File: scm.info, Node: Process Synchronization, Next: Files and Ports, Prev: Interrupts, Up: The Language Process Synchronization ======================= An "exchanger" is a procedure of one argument regulating mutually exclusive access to a resource. When a exchanger is called, its current content is returned, while being replaced by its argument in an atomic operation. - Function: make-exchanger obj Returns a new exchanger with the argument OBJ as its initial content. (define queue (make-exchanger (list a))) A queue implemented as an exchanger holding a list can be protected from reentrant execution thus: (define (pop queue) (let ((lst #f)) (dynamic-wind (lambda () (set! lst (queue #f))) (lambda () (and lst (not (null? lst)) (let ((ret (car lst))) (set! lst (cdr lst)) ret))) (lambda () (and lst (queue lst)))))) (pop queue) => a (pop queue) => #f - Function: make-arbiter name Returns an object of type arbiter and name NAME. Its state is initially unlocked. - Function: try-arbiter arbiter Returns `#t' and locks ARBITER if ARBITER was unlocked. Otherwise, returns `#f'. - Function: release-arbiter arbiter Returns `#t' and unlocks ARBITER if ARBITER was locked. Otherwise, returns `#f'.  File: scm.info, Node: Files and Ports, Next: Line Numbers, Prev: Process Synchronization, Up: The Language Files and Ports =============== These procedures generalize and extend the standard capabilities in *Note Ports: (r5rs)Ports. - Function: open-file string modes - Function: try-open-file string modes Returns a port capable of receiving or delivering characters as specified by the MODES string. If a file cannot be opened `#f' is returned. Internal functions opening files "callback" to the SCM function `open-file'. You can extend `open-file' by redefining it. `try-open-file' is the primitive procedure; Do not redefine `try-open-file'! - Constant: open_read - Constant: open_write - Constant: open_both Contain modes strings specifying that a file is to be opened for reading, writing, and both reading and writing respectively. Both input and output functions can be used with io-ports. An end of file must be read or a file-set-position done on the port between a read operation and a write operation or vice-versa. - Function: _ionbf modestr Returns a version of MODESTR which when `open-file' is called with it as the second argument will return an unbuffered port. An input-port must be unbuffered in order for `char-ready?' and `wait-for-input' to work correctly on it. The initial value of `(current-input-port)' is unbuffered if the platform supports it. - Function: _tracked modestr Returns a version of MODESTR which when `open-file' is called with it as the second argument will return a tracked port. A tracked port maintains current line and column numbers, which may be queried with `port-line' and `port-column'. - Function: _exclusive modestr Returns a version of MODESTR which when `open-file' is called with it as the second argument will return a port only if the named file does not already exist. This functionality is provided by calling `try-create-file' *Note I/O-Extensions::, which is not available for all platforms. - Function: port-closed? port Returns #t if PORT is closed. - Function: port-type obj If OBJ is not a port returns false, otherwise returns a symbol describing the port type, for example string or pipe. - Function: close-port port Closes PORT. The same as close-input-port and close-output-port. - Function: current-error-port Returns the current port to which diagnostic output is directed. - Function: with-error-to-file string thunk THUNK must be a procedure of no arguments, and string must be a string naming a file. The file is opened for output, an output port connected to it is made the default value returned by current-error-port, and the THUNK is called with no arguments. When the thunk returns, the port is closed and the previous default is restored. With-error-to-file returns the value yielded by THUNK. - Function: with-input-from-port port thunk - Function: with-output-to-port port thunk - Function: with-error-to-port port thunk These routines differ from with-input-from-file, with-output-to-file, and with-error-to-file in that the first argument is a port, rather than a string naming a file. - Function: call-with-outputs thunk proc Calls the THUNK procedure while the current-output-port and current-error-port are directed to string-ports. If THUNK returns, the PROC procedure is called with the output-string, the error-string, and the value returned by THUNK. If THUNK does not return a value (perhaps because of error), PROC is called with just the output-string and the error-string as arguments. - procedure: char-ready? - procedure: char-ready? port Returns `#t' if a character is ready on the input PORT and returns `#f' otherwise. If `char-ready?' returns `#t' then the next `read-char' operation on the given PORT is guaranteed not to hang. If the PORT is at end of file then `char-ready?' returns `#t'. PORT may be omitted, in which case it defaults to the value returned by `current-input-port'. _Rationale:_ `Char-ready?' exists to make it possible for a program to accept characters from interactive ports without getting stuck waiting for input. Any input editors associated with such ports must ensure that characters whose existence has been asserted by `char-ready?' cannot be rubbed out. If `char-ready?' were to return `#f' at end of file, a port at end of file would be indistinguishable from an interactive port that has no ready characters. - procedure: wait-for-input x - procedure: wait-for-input x port1 ... Returns a list those ports PORT1 ... which are `char-ready?'. If none of PORT1 ... become `char-ready?' within the time interval of X seconds, then #f is returned. The PORT1 ... arguments may be omitted, in which case they default to the list of the value returned by `current-input-port'. - Function: isatty? port Returns `#t' if PORT is input or output to a serial non-file device. - Function: freshline port Outputs a newline to optional argument PORT unless the current output column number of PORT is known to be zero, ie output will start at the beginning of a new line. PORT defaults to `current-output-port'. If PORT is not a tracked port `freshline' is equivalent to `newline'. - Function: open-ports Returns a list of all currently open ports, excluding string ports, see *Note String Ports: (slib)String Ports. This may be useful after a fork *Note Posix Extensions::, or for debugging. Bear in mind that ports that would be closed by gc will be kept open by a reference to this list.  File: scm.info, Node: Line Numbers, Next: Soft Ports, Prev: Files and Ports, Up: The Language Line Numbers ============ Scheme code define by load may optionally contain line number information. Currently this information is used only for reporting expansion time errors, but in the future run-time error messages may also include line number information. - Function: try-load pathname reader This is the primitive for loading, PATHNAME is the name of a file containing Scheme code, and optional argument READER is a function of one argument, a port. READER should read and return Scheme code as list structure. The default value is `read', which is used if READER is not supplied or is false. Line number objects are disjoint from integers or other Scheme types. When evaluated or loaded as Scheme code, an s-expression containing a line-number in the car is equivalent to the cdr of the s-expression. A pair consisting of a line-number in the car and a vector in the cdr is equivalent to the vector. The meaning of s-expressions with line-numbers in other positions is undefined. - Function: read-numbered port Behaves like `read', except that every s-expression read will be replaced with a cons of a line-number object and the sexp actually read. This replacement is done only if PORT is a tracked port See *Note Files and Ports::. - Function: integer->line-number int Returns a line-number object with value INT. INT should be an exact non-negative integer. - Function: line-number->integer linum Returns the value of line-number object LINUM as an integer. - Function: line-number? obj Returns true if and only if OBJ is a line-number object. - Variable: *load-reader* - Variable: *slib-load-reader* The value of `*load-reader*' should be a value acceptable as the second argument to `try-load' (note that #f is acceptable). This value will be used to read code during calls to `scm:load'. The value of `*slib-load-reader*' will similarly be used during calls to `slib:load' and `require'. In order to disable all line-numbering, it is sufficient to set! `*load-reader*' and `*slib-load-reader*' to #f.  File: scm.info, Node: Soft Ports, Next: Syntax Extensions, Prev: Line Numbers, Up: The Language Soft Ports ========== A "soft-port" is a port based on a vector of procedures capable of accepting or delivering characters. It allows emulation of I/O ports. - Function: make-soft-port vector modes Returns a port capable of receiving or delivering characters as specified by the MODES string (*note open-file: Files and Ports.). VECTOR must be a vector of length 6. Its components are as follows: 0. procedure accepting one character for output 1. procedure accepting a string for output 2. thunk for flushing output 3. thunk for getting one character 4. thunk for closing port (not by garbage collection) For an output-only port only elements 0, 1, 2, and 4 need be procedures. For an input-only port only elements 3 and 4 need be procedures. Thunks 2 and 4 can instead be `#f' if there is no useful operation for them to perform. If thunk 3 returns `#f' or an `eof-object' (*note eof-object?: (r5rs)Input.) it indicates that the port has reached end-of-file. For example: If it is necessary to explicitly close the port when it is garbage collected, (*note add-finalizer: Interrupts.). (define stdout (current-output-port)) (define p (make-soft-port (vector (lambda (c) (write c stdout)) (lambda (s) (display s stdout)) (lambda () (display "." stdout)) (lambda () (char-upcase (read-char))) (lambda () (display "@" stdout))) "rw")) (write p p) => #  File: scm.info, Node: Syntax Extensions, Next: Low Level Syntactic Hooks, Prev: Soft Ports, Up: The Language Syntax Extensions ================= - procedure: procedure-documentation proc Returns the documentation string of PROC if it exists, or `#f' if not. If the body of a `lambda' (or the definition of a procedure) has more than one expression, and the first expression (preceeding any internal definitions) is a string, then that string is the "documentation string" of that procedure. (procedure-documentation (lambda (x) "Identity" x)) => "Identity" (define (square x) "Return the square of X." (* x x)) => # (procedure-documentation square) => "Return the square of X." - Function: comment string1 ... Appends STRING1 ... to the strings given as arguments to previous calls `comment'. - Function: comment Returns the (appended) strings given as arguments to previous calls `comment' and empties the current string collection. - Read syntax: #;text-till-end-of-line Behaves as `(comment "TEXT-TILL-END-OF-LINE")'. - Read syntax: #. expression Is read as the object resulting from the evaluation of EXPRESSION. This substitution occurs even inside quoted structure. In order to allow compiled code to work with `#.' it is good practice to define those symbols used inside of EXPRESSION with `#.(define ...)'. For example: #.(define foo 9) => # '(#.foo #.(+ foo foo)) => (9 18) - Read syntax: #+ feature form If feature is `provided?' (by `*features*') then FORM is read as a scheme expression. If not, then FORM is treated as whitespace. Feature is a boolean expression composed of symbols and `and', `or', and `not' of boolean expressions. For more information on `provided?' and `*features*', *Note Require: (slib)Require. - Read syntax: #- feature form is equivalent to `#+(not feature) expression'. - Read syntax: #' form is equivalent to FORM (for compatibility with common-lisp). - Read syntax: #| any thing |# Is a balanced comment. Everything up to the matching `|#' is ignored by the `read'. Nested `#|...|#' can occur inside ANY THING. A similar read syntax "#!" (exclamation rather than vertical bar) is supported for Posix shell-scripts (*note Scripting::). - Read syntax: #\token If TOKEN is a sequence of two or more digits, then this syntax is equivalent to `#.(integer->char (string->number token 8))'. If TOKEN is `C-', `c-', or `^' followed by a character, then this syntax is read as a control character. If TOKEN is `M-' or `m-' followed by a character, then a meta character is read. `c-' and `m-' prefixes may be combined. - Special Form: defined? symbol Equivalent to `#t' if SYMBOL is a syntactic keyword (such as `if') or a symbol with a value in the top level environment (*note Variables and regions: (r5rs)Variables and regions.). Otherwise equivalent to `#f'. - Special Form: defvar identifier initial-value If IDENTIFIER is unbound in the top level environment, then IDENTIFIER is `define'd to the result of evaluating the form INITIAL-VALUE as if the `defvar' form were instead the form `(define identifier initial-value)' . If IDENTIFIER already has a value, then INITIAL-VALUE is _not_ evaluated and IDENTIFIER's value is not changed. `defconst' is valid only when used at top-level. - Special Form: defconst identifier value If IDENTIFIER is unbound in the top level environment, then IDENTIFIER is `define'd to the result of evaluating the form VALUE as if the `defconst' form were instead the form `(define identifier value)' . If IDENTIFIER already has a value, then VALUE is _not_ evaluated, IDENTIFIER's value is not changed, and an error is signaled. `defconst' is valid only when used at top-level. - Special Form: set! (variable1 variable2 ...) The identifiers VARIABLE1, VARIABLE2, ... must be bound either in some region enclosing the `set!' expression or at top level. is evaluated, and the elements of the resulting list are stored in the locations to which each corresponding VARIABLE is bound. The result of the `set!' expression is unspecified. (define x 2) (define y 3) (+ x y) => 5 (set! (x y) (list 4 5)) => _unspecified_ (+ x y) => 9 - Special Form: qase key clause1 clause2 ... `qase' is an extension of standard Scheme `case': Each CLAUSE of a `qase' statement must have as first element a list containing elements which are: * literal datums, or * a comma followed by the name of a symbolic constant, or * a comma followed by an at-sign (@) followed by the name of a symbolic constant whose value is a list. A `qase' statement is equivalent to a `case' statement in which these symbolic constants preceded by commas have been replaced by the values of the constants, and all symbolic constants preceded by comma-at-signs have been replaced by the elements of the list values of the constants. This use of comma, (or, equivalently, `unquote') is similar to that of `quasiquote' except that the unquoted expressions must be "symbolic constants". Symbolic constants are defined using `defconst', their values are substituted in the head of each `qase' clause during macro expansion. `defconst' constants should be defined before use. `qase' can be substituted for any correct use of `case'. (defconst unit '1) (defconst semivowels '(w y)) (qase (* 2 3) ((2 3 5 7) 'prime) ((,unit 4 6 8 9) 'composite)) ==> composite (qase (car '(c d)) ((a) 'a) ((b) 'b)) ==> _unspecified_ (qase (car '(c d)) ((a e i o u) 'vowel) ((,@semivowels) 'semivowel) (else 'consonant)) ==> consonant SCM also supports the following constructs from Common Lisp: `defmacro', `macroexpand', `macroexpand-1', and `gentemp'. *Note Defmacro: (slib)Defmacro. SCM `defmacro' is extended over that described for SLIB: (defmacro (macro-name . arguments) body) is equivalent to (defmacro macro-name arguments body) As in Common Lisp, an element of the formal argument list for `defmacro' may be a possibly nested list, in which case the corresponding actual argument must be a list with as many members as the formal argument. Rest arguments are indicated by improper lists, as in Scheme. It is an error if the actual argument list does not have the tree structure required by the formal argument list. For example: (defmacro (let1 ((name value)) . body) `((lambda (,name) ,@body) ,value)) (let1 ((x (foo))) (print x) x) == ((lambda (x) (print x) x) (foo)) (let1 not legal syntax) error--> not "does not match" ((name value)) SCM supports [R5RS] `syntax-rules' macros *Note Macros: (r5rs)Macros. The pattern language is extended by the syntax `(... )', which is identical to `' except that ellipses in `' are treated as ordinary identifiers in a template, or as literals in a pattern. In particular, `(... ...)' quotes the ellipsis token `...' in a pattern or template. For example: (define-syntax check-tree (syntax-rules () ((_ (?pattern (... ...)) ?obj) (let loop ((obj ?obj)) (or (null? obj) (and (pair? obj) (check-tree ?pattern (car obj)) (loop (cdr obj)))))) ((_ (?first . ?rest) ?obj) (let ((obj ?obj)) (and (pair? obj) (check-tree ?first (car obj)) (check-tree ?rest (cdr obj))))) ((_ ?atom ?obj) #t))) (check-tree ((a b) ...) '((1 2) (3 4) (5 6))) => #t (check-tree ((a b) ...) '((1 2) (3 4) not-a-2list) => #f Note that although the ellipsis is matched as a literal token in the defined macro it is not included in the literals list for `syntax-rules'. The pattern language is also extended to support identifier macros. A reference to an identifier macro keyword that is not the first identifier in a form may expand into Scheme code, rather than raising a "keyword as variable" error. The pattern for expansion of such a bare macro keyword is a single identifier, as in other syntax rules the identifier is ignored. For example: (define-syntax eight (syntax-rules () (_ 8))) (+ 3 eight) => 11 (eight) => ERROR (set! eight 9) => ERROR  File: scm.info, Node: Low Level Syntactic Hooks, Next: Syntactic Hooks for Hygienic Macros, Prev: Syntax Extensions, Up: The Language Low Level Syntactic Hooks ========================= - Callback procedure: read:sharp c port If a <#> followed by a character (for a non-standard syntax) is encountered by `read', `read' will call the value of the symbol `read:sharp' with arguments the character and the port being read from. The value returned by this function will be the value of `read' for this expression unless the function returns `#' in which case the expression will be treated as whitespace. `#' is the value returned by the expression `(if #f #f)'. - Callback procedure: read:sharp-char token If the sequence <#\> followed by a non-standard character name is encountered by `read', `read' will call the value of the symbol `read:sharp-char' with the token (a string of length at least two) as argument. If the value returned is a character, then that will be the value of `read' for this expression, otherwise an error will be signaled. _Note:_ When adding new <#> syntaxes, have your code save the previous value of `read:sharp' or `read:sharp-char' when defining it. Call this saved value if an invocation's syntax is not recognized. This will allow `#+', `#-', `#!', and *Note Uniform Array::s to still be supported (as they use `read:sharp'). - Function: procedure->syntax proc Returns a "macro" which, when a symbol defined to this value appears as the first symbol in an expression, returns the result of applying PROC to the expression and the environment. - Function: procedure->macro proc - Function: procedure->memoizing-macro proc - Function: procedure->identifier-macro Returns a "macro" which, when a symbol defined to this value appears as the first symbol in an expression, evaluates the result of applying PROC to the expression and the environment. The value returned from PROC which has been passed to `PROCEDURE->MEMOIZING-MACRO' replaces the form passed to PROC. For example: (defsyntax trace (procedure->macro (lambda (x env) `(set! ,(cadr x) (tracef ,(cadr x) ',(cadr x)))))) (trace foo) == (set! foo (tracef foo 'foo)). `PROCEDURE->IDENTIFIER-MACRO' is similar to `PROCEDURE->MEMOIZING-MACRO' except that PROC is also called in case the symbol bound to the macro appears in an expression but _not_ as the first symbol, that is, when it looks like a variable reference. In that case, the form passed to PROC is a single identifier. - Special Form: defsyntax name expr Defines NAME as a macro keyword bound to the result of evaluating EXPR, which should be a macro. Using `define' for this purpose may not result in NAME being interpreted as a macro keyword. An "environment" is a list of frames representing lexical bindings. Only the names and scope of the bindings are included in environments passed to macro expanders - run-time values are not included. There are several types of environment frames: `((lambda (variable1 ...) ...) value1 ...)' `(let ((variable1 value1) (variable2 value2) ...) ...)' `(letrec ((variable1 value1) ...) ...)' result in a single enviroment frame: (variable1 variable2 ...) `(let ((variable1 value1)) ...)' `(let* ((variable1 value1) ...) ...)' result in an environment frame for each variable: variable1 variable2 ... `(let-syntax ((key1 macro1) (key2 macro2)) ...)' `(letrec-syntax ((key1 value1) (key2 value2)) ...)' Lexically bound macros result in environment frames consisting of a marker and an alist of keywords and macro objects: ( (key1 . value1) (key2 . value2)) Currently is the integer 6. `line numbers' Line numbers (*note Line Numbers::) may be included in the environment as frame entries to indicate the line number on which a function is defined. They are ignored for variable lookup. # `miscellaneous' Debugging information is stored in environments in a plist format: Any exact integer stored as an environment frame may be followed by any value. The two frame entries are ignored when doing variable lookup. Load file names, procedure names, and closure documentation strings are stored in this format. "foo.scm" foo ... Currently is the integer 1 and the integer 2. - Special Form: @apply procedure argument-list Returns the result of applying PROCEDURE to ARGUMENT-LIST. `@apply' differs from `apply' when the identifiers bound by the closure being applied are `set!'; setting affects ARGUMENT-LIST. (define lst (list 'a 'b 'c)) (@apply (lambda (v1 v2 v3) (set! v1 (cons v2 v3))) lst) lst => ((b . c) b c) Thus a mutable environment can be treated as both a list and local bindings.  File: scm.info, Node: Syntactic Hooks for Hygienic Macros, Prev: Low Level Syntactic Hooks, Up: The Language Syntactic Hooks for Hygienic Macros =================================== SCM provides a synthetic identifier type for efficient implementation of hygienic macros (for example, `syntax-rules' *note Macros: (r5rs)Macros.) A synthetic identifier may be inserted in Scheme code by a macro expander in any context where a symbol would normally be used. Collectively, symbols and synthetic identifiers are _identifiers_. - Function: identifier? obj Returns `#t' if OBJ is a symbol or a synthetic identifier, and `#f' otherwise. If it is necessary to distinguish between symbols and synthetic identifiers, use the predicate `symbol?'. A synthetic identifier includes two data: a parent, which is an identifier, and an environment, which is either `#f' or a lexical environment which has been passed to a "macro expander" (a procedure passed as an argument to `procedure->macro', `procedure->memoizing-macro', or `procedure->syntax'). - Function: renamed-identifier parent env Returns a synthetic identifier. PARENT must be an identifier, and ENV must either be `#f' or a lexical environment passed to a macro expander. `renamed-identifier' returns a distinct object for each call, even if passed identical arguments. There is no direct way to access all of the data internal to a synthetic identifier, those data are used during variable lookup. If a synthetic identifier is inserted as quoted data then during macro expansion it will be repeatedly replaced by its parent, until a symbol is obtained. - Function: identifier->symbol id Returns the symbol obtained by recursively extracting the parent of ID, which must be an identifier. Use of synthetic identifiers ---------------------------- `renamed-identifier' may be used as a replacement for `gentemp': (define gentemp (let ((name (string->symbol "An unlikely variable"))) (lambda () (renamed-identifier name #f)))) If an identifier returned by this version of `gentemp' is inserted in a binding position as the name of a variable then it is guaranteed that no other identifier (except one produced by passing the first to `renamed-identifier') may denote that variable. If an identifier returned by `gentemp' is inserted free, then it will denote the top-level value bound to its parent, the symbol named "An unlikely variable". This behavior, of course, is meant to be put to good use: (define top-level-foo (procedure->memoizing-macro (lambda (exp env) (renamed-identifier 'foo #f)))) Defines a macro which may always be used to refer to the top-level binding of `foo'. (define foo 'top-level) (let ((foo 'local)) (top-level-foo)) => top-level In other words, we can avoid capturing `foo'. If a lexical environment is passed as the second argument to `renamed-identifier' then if the identifier is inserted free its parent will be looked up in that environment, rather than in the top-level environment. The use of such an identifier _must_ be restricted to the lexical scope of its environment. There is another restriction imposed for implementation convenience: Macros passing their lexical environments to `renamed-identifier' may be lexically bound only by the special forms `let-syntax' or `letrec-syntax'. No error is signaled if this restriction is not met, but synthetic identifier lookup will not work properly. In order to maintain referential transparency it is necessary to determine whether two identifiers have the same denotation. With synthetic identifiers it is not necessary that two identifiers be `eq?' in order to denote the same binding. - Function: identifier-equal? id1 id2 env Returns `#t' if identifiers ID1 and ID2 denote the same binding in lexical environment ENV, and `#f' otherwise. ENV must either be a lexical environment passed to a macro transformer during macro expansion or the empty list. For example, (define top-level-foo? (procedure->memoizing-macro (let ((foo-name (renamed-identifier 'foo #f))) (lambda (exp env) (identifier-equal? (cadr exp) foo-name env))))) (top-level-foo? foo) => #t (let ((foo 'local)) (top-level-foo? foo)) => #f - Function: @macroexpand1 expr env If the `car' of EXPR denotes a macro in ENV, then if that macro is a primitive, EXPR will be returned, if the macro was defined in Scheme, then a macro expansion will be returned. If the `car' of EXPR does not denote a macro, the `#f' is returned. - Function: extended-environment names values env Returns a new environment object, equivalent to ENV, which must either be an environment object or null, extended by one frame. NAMES must be an identifier, or an improper list of identifiers, usable as a formals list in a `lambda' expression. VALUES must be a list of objects long enough to provide a binding for each of the identifiers in NAMES. If NAMES is an identifier or an improper list then VALS may be, respectively, any object or an improper list of objects. - Special Form: syntax-quote obj Synthetic identifiers are converted to their parent symbols by `quote' and `quasiquote' so that literal data in macro definitions will be properly transcribed. `syntax-quote' behaves like `quote', but preserves synthetic identifier intact. - Special Form: the-macro mac `the-macro' is the simplest of all possible macro transformers: MAC may be a syntactic keyword (macro name) or an expression evaluating to a macro, otherwise an error is signaled. MAC is evaluated and returned once only, after which the same memoizied value is returned. `the-macro' may be used to protect local copies of macros against redefinition, for example: (@let-syntax ((let (the-macro let))) ;; code that will continue to work even if LET is redefined. ...) - Special Form: renaming-transformer proc A low-level "explicit renaming" macro facility very similar to that proposed by W. Clinger [Exrename] is supported. Syntax may be defined in `define-syntax', `let-syntax', and `letrec-syntax' using `renaming-transformer' instead of `syntax-rules'. PROC should evaluate to a procedure accepting three arguments: EXPR, RENAME, and COMPARE. EXPR is a representation of Scheme code to be expanded, as list structure. RENAME is a procedure accepting an identifier and returning an identifier renamed in the definition environment of the new syntax. COMPARE accepts two identifiers and returns true if and only if both denote the same binding in the usage environment of the new syntax.  File: scm.info, Node: Packages, Next: The Implementation, Prev: The Language, Up: Top Packages ******** * Menu: * Dynamic Linking:: * Dump:: Create Fast-Booting Executables * Numeric:: Numeric Language Extensions * Arrays:: As in APL * Records:: Define new aggregate data types * I/O-Extensions:: i/o-extensions * Posix Extensions:: posix * Unix Extensions:: non-posix unix * Regular Expression Pattern Matching:: regex * Line Editing:: edit-line * Curses:: Screen Control * Sockets:: Cruise the Net * Menu: * Xlib: (Xlibscm). X Window Graphics. * Hobbit: (hobbit). Scheme-to-C Compiler.  File: scm.info, Node: Dynamic Linking, Next: Dump, Prev: Packages, Up: Packages Dynamic Linking =============== If SCM has been compiled with `dynl.c' then the additional properties of load and ([SLIB]) require specified here are supported. The `require' form is preferred. - Function: require feature If the symbol FEATURE has not already been given as an argument to `require', then the object and library files associated with FEATURE will be dynamically-linked, and an unspecified value returned. If FEATURE is not found in `*catalog*', then an error is signaled. - Function: usr:lib lib Returns the pathname of the C library named LIB. For example: `(usr:lib "m")' returns `"/usr/lib/libm.a"', the path of the C math library. - Function: x:lib lib Returns the pathname of the X library named LIB. For example: `(x:lib "X11")' returns `"/usr/X11/lib/libX11.sa"', the path of the X11 library. - Function: load filename lib1 ... In addition to the [R5RS] requirement of loading Scheme expressions if FILENAME is a Scheme source file, `load' will also dynamically load/link object files (produced by `compile-file', for instance). The object-suffix need not be given to load. For example, (load (in-vicinity (implementation-vicinity) "sc2")) or (load (in-vicinity (implementation-vicinity) "sc2.o")) or (require 'rev2-procedures) or (require 'rev3-procedures) will load/link `sc2.o' if it exists. The LIB1 ... pathnames specify additional libraries which may be needed for object files not produced by the Hobbit compiler. For instance, crs is linked on Linux by (load (in-vicinity (implementation-vicinity) "crs.o") (usr:lib "ncurses") (usr:lib "c")) or (require 'curses) Turtlegr graphics library is linked by: (load (in-vicinity (implementation-vicinity) "turtlegr") (usr:lib "X11") (usr:lib "c") (usr:lib "m")) or (require 'turtle-graphics) And the string regular expression (*note Regular Expression Pattern Matching::) package is linked by: (load (in-vicinity (implementation-vicinity) "rgx") (usr:lib "c")) or (require 'regex) The following functions comprise the low-level Scheme interface to dynamic linking. See the file `Link.scm' in the SCM distribution for an example of their use. - Function: dyn:link filename FILENAME should be a string naming an "object" or "archive" file, the result of C-compiling. The `dyn:link' procedure links and loads FILENAME into the current SCM session. If successfull, `dyn:link' returns a "link-token" suitable for passing as the second argument to `dyn:call'. If not successful, `#f' is returned. - Function: dyn:call name link-token LINK-TOKEN should be the value returned by a call to `dyn:link'. NAME should be the name of C function of no arguments defined in the file named FILENAME which was succesfully `dyn:link'ed in the current SCM session. The `dyn:call' procedure calls the C function corresponding to NAME. If successful, `dyn:call' returns `#t'; If not successful, `#f' is returned. `dyn:call' is used to call the "init_..." function after loading SCM object files. The init_... function then makes the identifiers defined in the file accessible as Scheme procedures. - Function: dyn:main-call name link-token arg1 ... LINK-TOKEN should be the value returned by a call to `dyn:link'. NAME should be the name of C function of 2 arguments, `(int argc, char **argv)', defined in the file named FILENAME which was succesfully `dyn:link'ed in the current SCM session. The `dyn:main-call' procedure calls the C function corresponding to NAME with `argv' style arguments, such as are given to C `main' functions. If successful, `dyn:main-call' returns the integer returned from the call to NAME. `dyn:main-call' can be used to call a `main' procedure from SCM. For example, I link in and `dyn:main-call' a large C program, the low level routines of which callback (*note Callbacks::) into SCM (which emulates PCI hardware). - Function: dyn:unlink link-token LINK-TOKEN should be the value returned by a call to `dyn:link'. The `dyn:unlink' procedure removes the previously loaded file from the current SCM session. If successful, `dyn:unlink' returns `#t'; If not successful, `#f' is returned.  File: scm.info, Node: Dump, Next: Numeric, Prev: Dynamic Linking, Up: Packages Dump ==== "Dump", (also known as "unexec"), saves the continuation of an entire SCM session to an executable file, which can then be invoked as a program. Dumped executables start very quickly, since no Scheme code has to be loaded. There are constraints on which sessions are savable using `dump' * Saved continuations are invalid in subsequent invocations; they cause segmentation faults and other unpleasant side effects. * Although DLD (*note Dynamic Linking::) can be used to load compiled modules both before and after dumping, `SUN_DL' ELF systems can load compiled modules only after dumping. This can be worked around by compiling in those features you wish to `dump'. * Ports (other than `current-input-port', `current-output-port', `current-error-port'), X windows, etc. are invalid in subsequent invocations. This restriction could be removed; *Note Improvements To Make::. * `Dump' should only be called from a loading file when the call to dump is the last expression in that file. * `Dump' can be called from the command line. - Function: dump newpath - Function: dump newpath #f - Function: dump newpath #t - Function: dump newpath thunk * Calls `gc'. * Creates an executable program named NEWPATH which continues the state of the current SCM session when invoked. The optional argument THUNK, if provided, should be a procedure of no arguments; BOOT-TAIL will be set to this procedure, causing it to be called in the restored executable. If the optional argument is missing or a boolean, SCM's standard command line processing will be called in the restored executable. If the second argument to `dump' is `#t', argument processing will continue from the command line passed to the dumping session. If the second argument is missing or `#f' then the command line arguments of the restoring invocation will be processed. * Resumes the top level Read-Eval-Print loop. This is done instead of continuing normally to avoid creating a saved continuation in the dumped executable. `dump' may set the values of `boot-tail', `*argv*', `restart', and *INTERACTIVE*. `dump' returns an unspecified value. When a dumped executable is invoked, the variable *INTERACTIVE* (*note Internal State::) has the value it possessed when `dump' created it. Calling `dump' with a single argument sets *INTERACTIVE* to `#f', which is the state it has at the beginning of command line processing. The procedure `program-arguments' returns the command line arguments for the curent invocation. More specifically, `program-arguments' for the restored session are _not_ saved from the dumping session. Command line processing is done on the value of the identifier `*argv*'. The following example shows how to create `rscm', which is like regular scm, but which loads faster and has the `random' package alreadly provided. bash$ scm -rrandom > (dump "rscm") # > (quit) bash$ ./rscm -lpi.scm -e"(pi (random 200) 5)" 00003 14159 26535 89793 23846 26433 83279 50288 41971 69399 37510 58209 74944 59230 78164 06286 20899 86280 34825 34211 70679 82148 08651 32823 06647 09384 46095 50582 23172 53594 08128 48111 74502 84102 70193 85211 05559 64462 29489 bash$ This task can also be accomplished using the `-o' command line option (*note SCM Options::). bash$ scm -rrandom -o rscm > (quit) bash$ ./rscm -lpi.scm -e"(pi (random 200) 5)" 00003 14159 26535 89793 23846 26433 83279 50288 41971 69399 37510 58209 74944 59230 78164 06286 20899 86280 34825 34211 70679 82148 08651 32823 06647 09384 46095 50582 23172 53594 08128 48111 74502 84102 70193 85211 05559 64462 29489 bash$  File: scm.info, Node: Numeric, Next: Arrays, Prev: Dump, Up: Packages Numeric ======= - Constant: most-positive-fixnum The immediate integer closest to positive infinity. *Note Configuration: (slib)Configuration. - Constant: most-negative-fixnum The immediate integer closest to negative infinity. - Constant: $pi - Constant: pi The ratio of the circumference to the diameter of a circle. These procedures augment the standard capabilities in *Note Numerical operations: (r5rs)Numerical operations. - Function: pi* z `(* pi Z)' - Function: pi/ z `(/ pi Z)' - Function: sinh z - Function: cosh z - Function: tanh z Return the hyperbolic sine, cosine, and tangent of Z - Function: asinh z - Function: acosh z - Function: atanh z Return the inverse hyperbolic sine, cosine, and tangent of Z - Function: $sqrt x - Function: $abs x - Function: $exp x - Function: $log x - Function: $sin x - Function: $cos x - Function: $tan x - Function: $asin x - Function: $acos x - Function: $atan x - Function: $sinh x - Function: $cosh x - Function: $tanh x - Function: $asinh x - Function: $acosh x - Function: $atanh x Real-only versions of these popular functions. The argument X must be a real number. It is an error if the value which should be returned by a call to these procedures is _not_ real. - Function: $log10 x Real-only base 10 logarithm. - Function: $atan2 y x Computes `(angle (make-rectangular x y))' for real numbers Y and X. - Function: $expt x1 x2 Returns real number X1 raised to the real power X2. It is an error if the value which should be returned by a call to `$expt' is not real.  File: scm.info, Node: Arrays, Next: Records, Prev: Numeric, Up: Packages Arrays ====== * Menu: * Conventional Arrays:: * Array Mapping:: array-for-each * Uniform Array:: * Bit Vectors::  File: scm.info, Node: Conventional Arrays, Next: Array Mapping, Prev: Arrays, Up: Arrays Conventional Arrays ------------------- "Arrays" read and write as a `#' followed by the "rank" (number of dimensions) followed by the character #\a or #\A and what appear as lists (of lists) of elements. The lists must be nested to the depth of the rank. For each depth, all lists must be the same length. (make-array 'ho 3 3) => #2A((ho ho ho) (ho ho ho) (ho ho ho)) The rank may be elided, in which case it is read as one. '#A(a b c) == '#(a b c) Unshared conventional (not uniform) 0-based arrays of rank 1 (dimension) are equivalent to (and can't be distinguished from) vectors. (make-array 'ho 3) => #(ho ho ho) When constructing an array, BOUND is either an inclusive range of indices expressed as a two element list, or an upper bound expressed as a single integer. So (make-array 'foo 3 3) == (make-array 'foo '(0 2) '(0 2)) - Function: array? obj Returns `#t' if the OBJ is an array, and `#f' if not. - Function: make-array initial-value bound1 bound2 ... Creates and returns an array that has as many dimensions as there are BOUNDs and fills it with INITIAL-VALUE. - Function: array-ref array index1 index2 ... Returns the INDEX1, INDEX2, ...'th element of ARRAY. - Function: array-in-bounds? array index1 index2 ... Returns `#t' if its arguments would be acceptable to ARRAY-REF. - Function: array-set! array new-value index1 index2 ... Sets the INDEX1, INDEX2, ...'th element of ARRAY to NEW-VALUE. The value returned by `array-set!' is unspecified. - Function: make-shared-array array mapper bound1 bound2 ... `make-shared-array' can be used to create shared subarrays of other arrays. The MAPPER is a function that translates coordinates in the new array into coordinates in the old array. A MAPPER must be linear, and its range must stay within the bounds of the old array, but it can be otherwise arbitrary. A simple example: (define fred (make-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 - Function: transpose-array array dim0 dim1 ... Returns an array sharing contents with ARRAY, but with dimensions arranged in a different order. There must be one DIM argument for each dimension of ARRAY. DIM0, DIM1, ... should be integers between 0 and the rank of the array to be returned. Each integer in that range must appear at least once in the argument list. The values of DIM0, DIM1, ... correspond to dimensions in the array to be returned, their positions in the argument list to dimensions of ARRAY. Several DIMs may have the same value, in which case the returned array will have smaller rank than ARRAY. examples: (transpose-array '#2A((a b) (c d)) 1 0) => #2A((a c) (b d)) (transpose-array '#2A((a b) (c d)) 0 0) => #1A(a d) (transpose-array '#3A(((a b c) (d e f)) ((1 2 3) (4 5 6))) 1 1 0) => #2A((a 4) (b 5) (c 6)) - Function: enclose-array array dim0 dim1 ... DIM0, DIM1 ... should be nonnegative integers less than the rank of ARRAY. ENCLOSE-ARRAY returns an array resembling an array of shared arrays. The dimensions of each shared array are the same as the DIMth dimensions of the original array, the dimensions of the outer array are the same as those of the original array that did not match a DIM. An enclosed array is not a general Scheme array. Its elements may not be set using `array-set!'. Two references to the same element of an enclosed array will be `equal?' but will not in general be `eq?'. The value returned by ARRAY-PROTOTYPE when given an enclosed array is unspecified. examples: (enclose-array '#3A(((a b c) (d e f)) ((1 2 3) (4 5 6))) 1) => # (enclose-array '#3A(((a b c) (d e f)) ((1 2 3) (4 5 6))) 1 0) => # - Function: array-shape array Returns a list of inclusive bounds of integers. (array-shape (make-array 'foo '(-1 3) 5)) => ((-1 3) (0 4)) - Function: array-dimensions array `Array-dimensions' is similar to `array-shape' but replaces elements with a `0' minimum with one greater than the maximum. So: (array-dimensions (make-array 'foo '(-1 3) 5)) => ((-1 3) 5) - Function: array-rank obj Returns the number of dimensions of OBJ. If OBJ is not an array, `0' is returned. - Function: array->list array Returns a list consisting of all the elements, in order, of ARRAY. In the case of a rank-0 array, returns the single element. - Function: array-copy! source destination Copies every element from vector or array SOURCE to the corresponding element of DESTINATION. DESTINATION must have the same rank as SOURCE, and be at least as large in each dimension. The order of copying is unspecified. - Function: serial-array-copy! source destination Same as `array-copy!' but guaranteed to copy in row-major order. - Function: array-fill! array fill Stores FILL in every element of ARRAY. The value returned is unspecified. - Function: array-equal? array0 array1 ... Returns `#t' iff all arguments are arrays with the same shape, the same type, and have corresponding elements which are either `equal?' or `array-equal?'. This function differs from `equal?' in that a one dimensional shared array may be ARRAY-EQUAL? but not EQUAL? to a vector or uniform vector. - Function: array-contents array - Function: array-contents array strict If ARRAY may be "unrolled" into a one dimensional shared array without changing their order (last subscript changing fastest), then `array-contents' returns that shared array, otherwise it returns `#f'. All arrays made by MAKE-ARRAY and CREATE-ARRAY may be unrolled, some arrays made by MAKE-SHARED-ARRAY may not be. If the optional argument STRICT is provided, a shared array will be returned only if its elements are stored internally contiguous in memory.  File: scm.info, Node: Array Mapping, Next: Uniform Array, Prev: Conventional Arrays, Up: Arrays Array Mapping ------------- `(require 'array-for-each)' - Function: array-map! array0 proc array1 ... If ARRAY1, ... are arrays, they must have the same number of dimensions as ARRAY0 and have a range for each index which includes the range for the corresponding index in ARRAY0. If they are scalars, that is, not arrays, vectors, or strings, then they will be converted internally to arrays of the appropriate shape. PROC is applied to each tuple of elements of ARRAY1 ... and the result is stored as the corresponding element in ARRAY0. The value returned is unspecified. The order of application is unspecified. - Function: serial-array-map! array0 proc array1 ... Same as ARRAY-MAP!, but guaranteed to apply PROC in row-major order. - Function: array-for-each proc array0 ... PROC is applied to each tuple of elements of ARRAY0 ... in row-major order. The value returned is unspecified. - Function: array-index-map! array proc applies PROC to the indices of each element of ARRAY in turn, storing the result in the corresponding element. The value returned and the order of application are unspecified. One can implement ARRAY-INDEXES as (define (array-indexes array) (let ((ra (apply make-array #f (array-shape array)))) (array-index-map! ra (lambda x x)) ra)) Another example: (define (apl:index-generator n) (let ((v (make-vector n 1))) (array-index-map! v (lambda (i) i)) v)) - Function: scalar->array scalar array prototype Returns a uniform array of the same shape as ARRAY, having only one shared element, which is `eqv?' to SCALAR. If the optional argument PROTOTYPE is supplied it will be used as the prototype for the returned array. Otherwise the returned array will be of the same type as `array' if that is possible, and a conventional array if it is not. This function is used internally by `array-map!' and friends to handle scalar arguments.  File: scm.info, Node: Uniform Array, Next: Bit Vectors, Prev: Array Mapping, Up: Arrays Uniform Array ------------- "Uniform Arrays" and vectors are arrays whose elements are all of the same type. Uniform vectors occupy less storage than conventional vectors. Uniform Array procedures also work on vectors, uniform-vectors, bit-vectors, and strings. SLIB now supports uniform arrys. The primary array creation procedure is `create-array', detailed in *Note Arrays: (slib)Arrays. Unshared uniform character 0-based arrays of rank 1 (dimension) are equivalent to (and can't be distinguished from) strings. (create-array "" 3) => "$q2" Unshared uniform boolean 0-based arrays of rank 1 (dimension) are equivalent to (and can't be distinguished from) *Note bit-vectors: Bit Vectors. (create-array '#at() 3) => #*000 == #At(#f #f #f) => #*000 == #1At(#f #f #f) => #*000 PROTOTYPE arguments in the following procedures are interpreted according to the table: prototype type display prefix () conventional vector #a +64i complex (double precision) #ac64 64.0 double (double precision) #ar64 32.0 float (single precision) #ar32 32 unsigned integer (32-bit) #au32 -32 signed integer (32-bit) #as32 -16 signed integer (16-bit) #as16 #\a char (string) #a\ #t boolean (bit-vector) #at Other uniform vectors are written in a form similar to that of general arrays, except that one or more modifying characters are put between the #\A character and the contents list. For example, `'#As32(3 5 9)' returns a uniform vector of signed integers. - Function: array? obj prototype Returns `#t' if the OBJ is an array of type corresponding to PROTOTYPE, and `#f' if not. - Function: array-prototype array Returns an object that would produce an array of the same type as ARRAY, if used as the PROTOTYPE for `list->uniform-array'. - Function: list->uniform-array rank prot lst Returns a uniform array of the type indicated by prototype PROT with elements the same as those of LST. Elements must be of the appropriate type, no coercions are done. In, for example, the case of a rank-2 array, LST must be a list of lists, all of the same length. The length of LST will be the first dimension of the result array, and the length of each element the second dimension. If RANK is zero, LST, which need not be a list, is the single element of the returned array. - Function: uniform-vector-fill! uve fill Stores FILL in every element of UVE. The value returned is unspecified. - Function: dimensions->uniform-array dims prototype fill - Function: dimensions->uniform-array dims prototype Creates and returns a uniform array or vector of type corresponding to PROTOTYPE with dimensions DIMS or length LENGTH. If the FILL argument is supplied, the returned array is filled with this value. - Function: uniform-array-read! ura - Function: uniform-array-read! ura port Attempts to read all elements of URA, in lexicographic order, as binary objects from PORT. If an end of file is encountered during uniform-array-read! the objects up to that point only are put into URA (starting at the beginning) and the remainder of the array is unchanged. `uniform-array-read!' returns the number of objects read. PORT may be omitted, in which case it defaults to the value returned by `(current-input-port)'. - Function: uniform-array-write ura - Function: uniform-array-write ura port Writes all elements of URA as binary objects to PORT. The number of of objects actually written is returned. PORT may be omitted, in which case it defaults to the value returned by `(current-output-port)'. - Function: logaref array index1 index2 ... If an INDEX is provided for each dimension of ARRAY returns the INDEX1, INDEX2, ...'th element of ARRAY. If one more INDEX is provided, then the last index specifies bit position of the twos-complement representation of the array element indexed by the other INDEXs returning `#t' if the bit is 1, and `#f' if 0. It is an error if this element is not an exact integer. (logaref '#(#b1101 #b0010) 0) => #b1101 (logaref '#(#b1101 #b0010) 0 1) => #f (logaref '#2((#b1101 #b0010)) 0 0) => #b1101 - Function: logaset! array val index1 index2 ... If an INDEX is provided for each dimension of ARRAY sets the INDEX1, INDEX2, ...'th element of ARRAY to VAL. If one more INDEX is provided, then the last index specifies bit position of the twos-complement representation of an exact integer array element, setting the bit to 1 if VAL is `#t' and to 0 if VAL is `#f'. In this case it is an error if the array element is not an exact integer or if VAL is not boolean.  File: scm.info, Node: Bit Vectors, Prev: Uniform Array, Up: Arrays Bit Vectors ----------- Bit vectors can be written and read as a sequence of `0's and `1's prefixed by `#*'. #At(#f #f #f #t #f #t #f) => #*0001010 Some of these operations will eventually be generalized to other uniform-arrays. - Function: bit-count bool bv Returns the number occurrences of BOOL in BV. - Function: bit-position bool bv k Returns the minimum index of an occurrence of BOOL in BV which is at least K. If no BOOL occurs within the specified range `#f' is returned. - Function: bit-invert! bv Modifies BV by replacing each element with its negation. - Function: bit-set*! bv uve bool If uve is a bit-vector BV and uve must be of the same length. If BOOL is `#t', uve is OR'ed into BV; If BOOL is `#f', the inversion of uve is AND'ed into BV. If uve is a unsigned integer vector all the elements of uve must be between 0 and the `LENGTH' of BV. The bits of BV corresponding to the indexes in uve are set to BOOL. The return value is unspecified. - Function: bit-count* bv uve bool Returns (bit-count (bit-set*! (if bool bv (bit-invert! bv)) uve #t) #t). BV is not modified.  File: scm.info, Node: Records, Next: I/O-Extensions, Prev: Arrays, Up: Packages Records ======= SCM provides user-definable datatypes with the same interface as SLIB, see *Note Records: (slib)Records, with the following extension. - Function: record-printer-set! rtd printer Causes records of type RTD to be printed in a user-specified format. RTD must be a record type descriptor returned by `make-record-type', PRINTER a procedure accepting three arguments: the record to be printed, the port to print to, and a boolean which is true if the record is being written on behalf of `write' and false if for `display'. If PRINTER returns #f, the default record printer will be called. A PRINTER value of #f means use the default printer. Only the default printer will be used when printing error messages.  File: scm.info, Node: I/O-Extensions, Next: Posix Extensions, Prev: Records, Up: Packages I/O-Extensions ============== If `'i/o-extensions' is provided (by linking in `ioext.o'), *Note Line I/O: (slib)Line I/O, and the following functions are defined: - Function: stat Returns a vector of integers describing the argument. The argument can be either a string or an open input port. If the argument is an open port then the returned vector describes the file to which the port is opened; If the argument is a string then the returned vector describes the file named by that string. If there exists no file with the name string, or if the file cannot be accessed `#f' is returned. The elements of the returned vector are as follows: 0 st_dev ID of device containing a directory entry for this file 1 st_ino Inode number 2 st_mode File type, attributes, and access control summary 3 st_nlink Number of links 4 st_uid User ID of file owner 5 st_gid Group ID of file group 6 st_rdev Device ID; this entry defined only for char or blk spec files 7 st_size File size (bytes) 8 st_atime Time of last access 9 st_mtime Last modification time 10 st_ctime Last file status change time - Function: getpid Returns the process ID of the current process. - Function: file-position port Returns the current position of the character in PORT which will next be read or written. If PORT is not open to a file the result is unspecified. - Function: file-set-position port integer Sets the current position in PORT which will next be read or written. If PORT is not open to a file the action of `file-set-position' is unspecified. The result of `file-set-position' is unspecified. - Function: try-create-file name modes perms If the file with name NAME already exists, return `#f', otherwise try to create and open the file like `try-open-file', *Note Files and Ports::. If the optional integer argument PERMS is provided, it is used as the permissions of the new file (modified by the current umask). - Function: reopen-file filename modes port Closes port PORT and reopens it with FILENAME and MODES. `reopen-file' returns `#t' if successful, `#f' if not. - Function: duplicate-port port modes Creates and returns a "duplicate" port from PORT. Duplicate _unbuffered_ ports share one file position. MODES are as for *Note open-file: Files and Ports. - Function: redirect-port! from-port to-port Closes TO-PORT and makes TO-PORT be a duplicate of FROM-PORT. `redirect-port!' returns TO-PORT if successful, `#f' if not. If unsuccessful, TO-PORT is not closed. - Function: opendir dirname Returns a "directory" object corresponding to the file system directory named DIRNAME. If unsuccessful, returns `#f'. - Function: readdir dir Returns the string name of the next entry from the directory DIR. If there are no more entries in the directory, `readdir' returns a `#f'. - Function: rewinddir dir Reinitializes DIR so that the next call to `readdir' with DIR will return the first entry in the directory again. - Function: closedir dir Closes DIR and returns `#t'. If DIR is already closed,, `closedir' returns a `#f'. - Function: directory-for-each proc directory The LISTs must be lists, and PROC must be a procedure taking one argument. `Directory-For-Each' applies PROC to the (string) name of each file in DIRECTORY. The dynamic order in which PROC is applied to the elements of the LISTs is unspecified. The value returned by `directory-for-each' is unspecified. - Function: directory-for-each proc directory pred Applies PROC only to those filenames for which the procedure PRED returns a non-false value. - Function: directory-for-each proc directory match Applies PROC only to those filenames for which `(filename:match?? MATCH)' would return a non-false value (*note Filenames: (slib)Filenames.). (require 'directory-for-each) (directory-for-each print "." "[A-Z]*.scm") -| "Init.scm" "Iedline.scm" "Link.scm" "Macro.scm" "Transcen.scm" "Init5d6.scm" - Function: mkdir path mode The `mkdir' function creates a new, empty directory whose name is PATH. The integer argument MODE specifies the file permissions for the new directory. *Note The Mode Bits for Access Permission: (libc)The Mode Bits for Access Permission, for more information about this. `mkdir' returns if successful, `#f' if not. - Function: rmdir path The `rmdir' function deletes the directory PATH. The directory must be empty before it can be removed. `rmdir' returns if successful, `#f' if not. - Function: chdir filename Changes the current directory to FILENAME. If FILENAME does not exist or is not a directory, `#f' is returned. Otherwise, `#t' is returned. - Function: getcwd The function `getcwd' returns a string containing the absolute file name representing the current working directory. If this string cannot be obtained, `#f' is returned. - Function: rename-file oldfilename newfilename Renames the file specified by OLDFILENAME to NEWFILENAME. If the renaming is successful, `#t' is returned. Otherwise, `#f' is returned. - Function: chmod file mode The function `chmod' sets the access permission bits for the file named by FILE to MODE. The FILE argument may be a string containing the filename or a port open to the file. `chmod' returns if successful, `#f' if not. - Function: utime pathname acctime modtime Sets the file times associated with the file named PATHNAME to have access time ACCTIME and modification time MODTIME. `utime' returns if successful, `#f' if not. - Function: umask mode The function `umask' sets the file creation mask of the current process to MASK, and returns the previous value of the file creation mask. - Function: fileno port Returns the integer file descriptor associated with the port PORT. If an error is detected, `#f' is returned. - Function: access pathname how Returns `#t' if the file named by PATHNAME can be accessed in the way specified by the HOW argument. The HOW argument can be the `logior' of the flags: 0. File-exists? 1. File-is-executable? 2. File-is-writable? 4. File-is-readable? Or the HOW argument can be a string of 0 to 3 of the following characters in any order. The test performed is the `and' of the associated tests and `file-exists?'. File-is-executable? File-is-writable? File-is-readable? - Function: execl command arg0 ... - Function: execlp command arg0 ... Transfers control to program COMMAND called with arguments ARG0 .... For `execl', COMMAND must be an exact pathname of an executable file. `execlp' searches for COMMAND in the list of directories specified by the environment variable PATH. The convention is that ARG0 is the same name as COMMAND. If successful, this procedure does not return. Otherwise an error message is printed and the integer `errno' is returned. - Function: execv command arglist - Function: execvp command arglist Like `execl' and `execlp' except that the set of arguments to COMMAND is ARGLIST. - Function: putenv string adds or removes definitions from the "environment". If the STRING is of the form `NAME=VALUE', the definition is added to the environment. Otherwise, the STRING is interpreted as the name of an environment variable, and any definition for this variable in the environment is removed. Names of environment variables are case-sensitive and must not contain the character `='. System-defined environment variables are invariably uppercase. `Putenv' is used to set up the environment before calls to `execl', `execlp', `execv', `execvp', `system', or `open-pipe' (*note open-pipe: Posix Extensions.). To access environment variables, use `getenv' (*note getenv: (slib)System Interface.).  File: scm.info, Node: Posix Extensions, Next: Unix Extensions, Prev: I/O-Extensions, Up: Packages Posix Extensions ================ If `'posix' is provided (by linking in `posix.o'), the following functions are defined: - Function: open-pipe string modes If the string MODES contains an , returns an input port capable of delivering characters from the standard output of the system command STRING. Otherwise, returns an output port capable of receiving characters which become the standard input of the system command STRING. If a pipe cannot be created `#f' is returned. - Function: open-input-pipe string Returns an input port capable of delivering characters from the standard output of the system command STRING. If a pipe cannot be created `#f' is returned. - Function: open-output-pipe string Returns an output port capable of receiving characters which become the standard input of the system command STRING. If a pipe cannot be created `#f' is returned. - Function: broken-pipe port If this function is defined at top level, it will be called when an output pipe is closed from the other side (this is the condition under which a SIGPIPE is sent). The already closed PORT will be passed so that any necessary cleanup may be done. An error is not signaled when output to a pipe fails in this way, but any further output to the closed pipe will cause an error to be signaled. - Function: close-port pipe Closes the PIPE, rendering it incapable of delivering or accepting characters. This routine has no effect if the pipe has already been closed. The value returned is unspecified. - Function: pipe Returns `(cons RD WD)' where RD and WD are the read and write (port) ends of a "pipe" respectively. - Function: fork Creates a copy of the process calling `fork'. Both processes return from `fork', but the calling ("parent") process's `fork' returns the "child" process's ID whereas the child process's `fork' returns 0. For a discussion of "ID"s *Note Process Persona: (GNU C Library)Process Persona. - Function: getppid Returns the process ID of the parent of the current process. For a process's own ID *Note getpid: I/O-Extensions. - Function: getlogin Returns the (login) name of the user logged in on the controlling terminal of the process, or #f if this information cannot be determined. - Function: getuid Returns the real user ID of this process. - Function: getgid Returns the real group ID of this process. - Function: getegid Returns the effective group ID of this process. - Function: geteuid Returns the effective user ID of this process. - Function: setuid id Sets the real user ID of this process to ID. Returns `#t' if successful, `#f' if not. - Function: setgid id Sets the real group ID of this process to ID. Returns `#t' if successful, `#f' if not. - Function: setegid id Sets the effective group ID of this process to ID. Returns `#t' if successful, `#f' if not. - Function: seteuid id Sets the effective user ID of this process to ID. Returns `#t' if successful, `#f' if not. - Function: kill pid sig The `kill' function sends the signal SIGNUM to the process or process group specified by PID. Besides the signals listed in *Note Standard Signals: (libc)Standard Signals, SIGNUM can also have a value of zero to check the validity of the PID. The PID specifies the process or process group to receive the signal: > 0 The process whose identifier is PID. 0 All processes in the same process group as the sender. The sender itself does not receive the signal. -1 If the process is privileged, send the signal to all processes except for some special system processes. Otherwise, send the signal to all processes with the same effective user ID. < -1 The process group whose identifier is `(abs PID)'. A process can send a signal to itself with `(kill (getpid) SIGNUM)'. If `kill' is used by a process to send a signal to itself, and the signal is not blocked, then `kill' delivers at least one signal (which might be some other pending unblocked signal instead of the signal SIGNUM) to that process before it returns. The return value from `kill' is zero if the signal can be sent successfully. Otherwise, no signal is sent, and a value of `-1' is returned. If PID specifies sending a signal to several processes, `kill' succeeds if it can send the signal to at least one of them. There's no way you can tell which of the processes got the signal or whether all of them did. - Function: waitpid pid options The `waitpid' function suspends execution of the current process until a child as specified by the PID argument has exited, or until a signal is delivered whose action is to terminate the current process or to call a signal handling function. If a child as requested by PID has already exited by the time of the call (a so-called "zombie" process), the function returns immediately. Any system resources used by the child are freed. The value of PID can be: < -1 which means to wait for any child process whose process group ID is equal to the absolute value of PID. -1 which means to wait for any child process; this is the same behaviour which wait exhibits. 0 which means to wait for any child process whose process group ID is equal to that of the calling process. > 0 which means to wait for the child whose process ID is equal to the value of PID. The value of OPTIONS is one of the following: 0. Nothing special. 1. (`WNOHANG') which means to return immediately if no child is there to be waited for. 2. (`WUNTRACED') which means to also return for children which are stopped, and whose status has not been reported. 3. Which means both of the above. The return value normally is the exit status of the child process, including the exit value along with flags indicating whether a coredump was generated or the child terminated as a result of a signal. If the `WNOHANG' option was specified and no child process is waiting to be noticed, the value is zero. A value of `#f' is returned in case of error and `errno' is set. For information about the `errno' codes *Note Process Completion: (GNU C Library)Process Completion. - Function: uname You can use the `uname' procedure to find out some information about the type of computer your program is running on. Returns a vector of strings. These strings are: 0. The name of the operating system in use. 1. The network name of this particular computer. 2. The current release level of the operating system implementation. 3. The current version level within the release of the operating system. 4. Description of the type of hardware that is in use. Some examples are `"i386-ANYTHING"', `"m68k-hp"', `"sparc-sun"', `"m68k-sun"', `"m68k-sony"' and `"mips-dec"'. - Function: getpw name - Function: getpw uid - Function: getpw Returns a vector of information for the entry for `NAME', `UID', or the next entry if no argument is given. The information is: 0. The user's login name. 1. The encrypted password string. 2. The user ID number. 3. The user's default group ID number. 4. A string typically containing the user's real name, and possibly other information such as a phone number. 5. The user's home directory, initial working directory, or `#f', in which case the interpretation is system-dependent. 6. The user's default shell, the initial program run when the user logs in, or `#f', indicating that the system default should be used. - Function: setpwent #t Rewinds the pw entry table back to the begining. - Function: setpwent #f - Function: setpwent Closes the pw table. - Function: getgr name - Function: getgr uid - Function: getgr Returns a vector of information for the entry for `NAME', `UID', or the next entry if no argument is given. The information is: 0. The name of the group. 1. The encrypted password string. 2. The group ID number. 3. A list of (string) names of users in the group. - Function: setgrent #t Rewinds the group entry table back to the begining. - Function: setgrent #f - Function: setgrent Closes the group table. - Function: getgroups Returns a vector of all the supplementary group IDs of the process. - Function: link oldname newname The `link' function makes a new link to the existing file named by OLDNAME, under the new name NEWNAME. `link' returns a value of `#t' if it is successful and `#f' on failure. - Function: chown filename owner group The `chown' function changes the owner of the file FILENAME to OWNER, and its group owner to GROUP. `chown' returns a value of `#t' if it is successful and `#f' on failure. - Function: ttyname port If port PORT is associated with a terminal device, returns a string containing the file name of termainal device; otherwise `#f'.  File: scm.info, Node: Unix Extensions, Next: Regular Expression Pattern Matching, Prev: Posix Extensions, Up: Packages Unix Extensions =============== If `'unix' is provided (by linking in `unix.o'), the following functions are defined: These "privileged" and symbolic link functions are not in Posix: - Function: symlink oldname newname The `symlink' function makes a symbolic link to OLDNAME named NEWNAME. `symlink' returns a value of `#t' if it is successful and `#f' on failure. - Function: readlink filename Returns the value of the symbolic link FILENAME or `#f' for failure. - Function: lstat filename The `lstat' function is like `stat', except that it does not follow symbolic links. If FILENAME is the name of a symbolic link, `lstat' returns information about the link itself; otherwise, `lstat' works like `stat'. *Note I/O-Extensions::. - Function: nice increment Increment the priority of the current process by INCREMENT. `chown' returns a value of `#t' if it is successful and `#f' on failure. - Function: acct filename When called with the name of an exisitng file as argument, accounting is turned on, records for each terminating process are appended to FILENAME as it terminates. An argument of `#f' causes accounting to be turned off. `acct' returns a value of `#t' if it is successful and `#f' on failure. - Function: mknod filename mode dev The `mknod' function makes a special file with name FILENAME and modes MODE for device number DEV. `mknod' returns a value of `#t' if it is successful and `#f' on failure. - Function: sync `sync' first commits inodes to buffers, and then buffers to disk. sync() only schedules the writes, so it may return before the actual writing is done. The value returned is unspecified.  File: scm.info, Node: Regular Expression Pattern Matching, Next: Line Editing, Prev: Unix Extensions, Up: Packages Regular Expression Pattern Matching =================================== These functions are defined in `rgx.c' using a POSIX or GNU "regex" library. If your computer does not support regex, a package is available via ftp from `ftp.gnu.org:/pub/gnu/regex-0.12.tar.gz'. For a description of regular expressions, *Note syntax: (regex)syntax. - Function: regcomp PATTERN [FLAGS] Compile a "regular expression". Return a compiled regular expression, or an integer error code suitable as an argument to `regerror'. FLAGS in `regcomp' is a string of option letters used to control the compilation of the regular expression. The letters may consist of: `n' newlines won't be matched by `.' or hat lists; ( `[^...]' ) `i' ignore case.only when compiled with _GNU_SOURCE: `0' allows dot to match a null character. `f' enable GNU fastmaps. - Function: regerror ERRNO Returns a string describing the integer ERRNO returned when `regcomp' fails. - Function: regexec RE STRING Returns `#f' or a vector of integers. These integers are in doublets. The first of each doublet is the index of STRING of the start of the matching expression or sub-expression (delimited by parentheses in the pattern). The last of each doublet is index of STRING of the end of that expression. `#f' is returned if the string does not match. - Function: regmatch? RE STRING Returns `#t' if the PATTERN such that REGEXP = (regcomp PATTERN) matches STRING as a POSIX extended regular expressions. Returns `#f' otherwise. - Function: regsearch RE STRING [START [LEN]] - Function: regsearchv RE STRING [START [LEN]] - Function: regmatch RE STRING [START [LEN]] - Function: regmatchv RE STRING [START [LEN]] `Regsearch' searches for the pattern within the string. `Regmatch' anchors the pattern and begins matching it against string. `Regsearch' returns the character position where RE starts, or `#f' if not found. `Regmatch' returns the number of characters matched, `#f' if not matched. `Regsearchv' and `regmatchv' return the match vector is returned if RE is found, `#f' otherwise. RE may be either: 1. a compiled regular expression returned by `regcomp'; 2. a string representing a regular expression; 3. a list of a string and a set of option letters. STRING The string to be operated upon. START The character position at which to begin the search or match. If absent, the default is zero. _Compiled _GNU_SOURCE and using GNU libregex only:_ When searching, if START is negative, the absolute value of START will be used as the start location and reverse searching will be performed. LEN The search is allowed to examine only the first LEN characters of STRING. If absent, the entire string may be examined. - Function: string-split RE STRING - Function: string-splitv RE STRING `String-split' splits a string into substrings that are separated by RE, returning a vector of substrings. `String-splitv' returns a vector of string positions that indicate where the substrings are located. - Function: string-edit RE EDIT-SPEC STRING [COUNT] Returns the edited string. EDIT-SPEC Is a string used to replace occurances of RE. Backquoted integers in the range of 1-9 may be used to insert subexpressions in RE, as in `sed'. COUNT The number of substitutions for `string-edit' to perform. If `#t', all occurances of RE will be replaced. The default is to perform one substitution.  File: scm.info, Node: Line Editing, Next: Curses, Prev: Regular Expression Pattern Matching, Up: Packages Line Editing ============ These procedures provide input line editing and recall. These functions are defined in `edline.c' and `Iedline.scm' using the "editline" or GNU "readline" (*note Overview: (readline)Top.) libraries available from: * `ftp.sys.toronto.edu:/pub/rc/editline.shar' * `ftp.gnu.org:/pub/gnu/readline-2.0.tar.gz' When `Iedline.scm' is loaded, if the current input port is the default input port and the environment variable EMACS is not defined, line-editing mode will be entered. - Function: default-input-port Returns the initial `current-input-port' SCM was invoked with (stdin). - Function: default-output-port Returns the initial `current-output-port' SCM was invoked with (stdout). - Function: make-edited-line-port Returns an input/output port that allows command line editing and retrieval of history. - Function: line-editing Returns the current edited line port or `#f'. - Function: line-editing bool If BOOL is false, exits line-editing mode and returns the previous value of `(line-editing)'. If BOOL is true, sets the current input and output ports to an edited line port and returns the previous value of `(line-editing)'.  File: scm.info, Node: Curses, Next: Sockets, Prev: Line Editing, Up: Packages Curses ====== These functions are defined in `crs.c' using the "curses" library. Unless otherwise noted these routines return `#t' for successful completion and `#f' for failure. - Function: initscr Returns a port for a full screen window. This routine must be called to initialize curses. - Function: endwin A program should call `endwin' before exiting or escaping from curses mode temporarily, to do a system call, for example. This routine will restore termio modes, move the cursor to the lower left corner of the screen and reset the terminal into the proper non-visual mode. To resume after a temporary escape, call *Note refresh: Window Manipulation. * Menu: * Output Options Setting:: * Terminal Mode Setting:: * Window Manipulation:: * Output:: * Input:: * Curses Miscellany::  File: scm.info, Node: Output Options Setting, Next: Terminal Mode Setting, Prev: Curses, Up: Curses Output Options Setting ---------------------- These routines set options within curses that deal with output. All options are initially `#f', unless otherwise stated. It is not necessary to turn these options off before calling `endwin'. - Function: clearok win bf If enabled (BF is `#t'), the next call to `force-output' or `refresh' with WIN will clear the screen completely and redraw the entire screen from scratch. This is useful when the contents of the screen are uncertain, or in some cases for a more pleasing visual effect. - Function: idlok win bf If enabled (BF is `#t'), curses will consider using the hardware "insert/delete-line" feature of terminals so equipped. If disabled (BF is `#f'), curses will very seldom use this feature. The "insert/delete-character" feature is always considered. This option should be enabled only if your application needs "insert/delete-line", for example, for a screen editor. It is disabled by default because "insert/delete-line" tends to be visually annoying when used in applications where it is not really needed. If "insert/delete-line" cannot be used, curses will redraw the changed portions of all lines. - Function: leaveok win bf Normally, the hardware cursor is left at the location of the window cursor being refreshed. This option allows the cursor to be left wherever the update happens to leave it. It is useful for applications where the cursor is not used, since it reduces the need for cursor motions. If possible, the cursor is made invisible when this option is enabled. - Function: scrollok win bf This option controls what happens when the cursor of window WIN is moved off the edge of the window or scrolling region, either from a newline on the bottom line, or typing the last character of the last line. If disabled (BF is `#f'), the cursor is left on the bottom line at the location where the offending character was entered. If enabled (BF is `#t'), `force-output' is called on the window WIN, and then the physical terminal and window WIN are scrolled up one line. _Note:_ in order to get the physical scrolling effect on the terminal, it is also necessary to call `idlok'. - Function: nodelay win bf This option causes wgetch to be a non-blocking call. If no input is ready, wgetch will return an eof-object. If disabled, wgetch will hang until a key is pressed.  File: scm.info, Node: Terminal Mode Setting, Next: Window Manipulation, Prev: Output Options Setting, Up: Curses Terminal Mode Setting --------------------- These routines set options within curses that deal with input. The options involve using ioctl(2) and therefore interact with curses routines. It is not necessary to turn these options off before calling `endwin'. The routines in this section all return an unspecified value. - Function: cbreak - Function: nocbreak These two routines put the terminal into and out of `CBREAK' mode, respectively. In `CBREAK' mode, characters typed by the user are immediately available to the program and erase/kill character processing is not performed. When in `NOCBREAK' mode, the tty driver will buffer characters typed until a or is typed. Interrupt and flowcontrol characters are unaffected by this mode. Initially the terminal may or may not be in `CBREAK' mode, as it is inherited, therefore, a program should call `cbreak' or `nocbreak' explicitly. Most interactive programs using curses will set `CBREAK' mode. _Note:_ `cbreak' overrides `raw'. For a discussion of how these routines interact with `echo' and `noecho' *Note read-char: Input. - Function: raw - Function: noraw The terminal is placed into or out of `RAW' mode. `RAW' mode is similar to `CBREAK' mode, in that characters typed are immediately passed through to the user program. The differences are that in `RAW' mode, the interrupt, quit, suspend, and flow control characters are passed through uninterpreted, instead of generating a signal. `RAW' mode also causes 8-bit input and output. The behavior of the `BREAK' key depends on other bits in the terminal driver that are not set by curses. - Function: echo - Function: noecho These routines control whether characters typed by the user are echoed by `read-char' as they are typed. Echoing by the tty driver is always disabled, but initially `read-char' is in `ECHO' mode, so characters typed are echoed. Authors of most interactive programs prefer to do their own echoing in a controlled area of the screen, or not to echo at all, so they disable echoing by calling `noecho'. For a discussion of how these routines interact with `echo' and `noecho' *Note read-char: Input. - Function: nl - Function: nonl These routines control whether is translated into and `LFD' on output, and whether is translated into on input. Initially, the translations do occur. By disabling these translations using `nonl', curses is able to make better use of the linefeed capability, resulting in faster cursor motion. - Function: resetty - Function: savetty These routines save and restore the state of the terminal modes. `savetty' saves the current state of the terminal in a buffer and `resetty' restores the state to what it was at the last call to `savetty'.  File: scm.info, Node: Window Manipulation, Next: Output, Prev: Terminal Mode Setting, Up: Curses Window Manipulation ------------------- - Function: newwin nlines ncols begy begx Create and return a new window with the given number of lines (or rows), NLINES, and columns, NCOLS. The upper left corner of the window is at line BEGY, column BEGX. If either NLINES or NCOLS is 0, they will be set to the value of `LINES'-BEGY and `COLS'-BEGX. A new full-screen window is created by calling `newwin(0,0,0,0)'. - Function: subwin orig nlines ncols begy begx Create and return a pointer to a new window with the given number of lines (or rows), NLINES, and columns, NCOLS. The window is at position (BEGY, BEGX) on the screen. This position is relative to the screen, and not to the window ORIG. The window is made in the middle of the window ORIG, so that changes made to one window will affect both windows. When using this routine, often it will be necessary to call `touchwin' or `touchline' on ORIG before calling `force-output'. - Function: close-port win Deletes the window WIN, freeing up all memory associated with it. In the case of sub-windows, they should be deleted before the main window WIN. - Function: refresh - Function: force-output win These routines are called to write output to the terminal, as most other routines merely manipulate data structures. `force-output' copies the window WIN to the physical terminal screen, taking into account what is already there in order to minimize the amount of information that's sent to the terminal (called optimization). Unless `leaveok' has been enabled, the physical cursor of the terminal is left at the location of window WIN's cursor. With `refresh', the number of characters output to the terminal is returned. - Function: mvwin win y x Move the window WIN so that the upper left corner will be at position (Y, X). If the move would cause the window WIN to be off the screen, it is an error and the window WIN is not moved. - Function: overlay srcwin dstwin - Function: overwrite srcwin dstwin These routines overlay SRCWIN on top of DSTWIN; that is, all text in SRCWIN is copied into DSTWIN. SRCWIN and DSTWIN need not be the same size; only text where the two windows overlap is copied. The difference is that `overlay' is non-destructive (blanks are not copied), while `overwrite' is destructive. - Function: touchwin win - Function: touchline win start count Throw away all optimization information about which parts of the window WIN have been touched, by pretending that the entire window WIN has been drawn on. This is sometimes necessary when using overlapping windows, since a change to one window will affect the other window, but the records of which lines have been changed in the other window will not reflect the change. `touchline' only pretends that COUNT lines have been changed, beginning with line START. - Function: wmove win y x The cursor associated with the window WIN is moved to line (row) Y, column X. This does not move the physical cursor of the terminal until `refresh' (or `force-output') is called. The position specified is relative to the upper left corner of the window WIN, which is (0, 0).  File: scm.info, Node: Output, Next: Input, Prev: Window Manipulation, Up: Curses Output ------ These routines are used to "draw" text on windows - Function: display ch win - Function: display str win - Function: wadd win ch - Function: wadd win str The character CH or characters in STR are put into the window WIN at the current cursor position of the window and the position of WIN's cursor is advanced. At the right margin, an automatic newline is performed. At the bottom of the scrolling region, if scrollok is enabled, the scrolling region will be scrolled up one line. If CH is a , , or backspace, the cursor will be moved appropriately within the window WIN. A also does a `wclrtoeol' before moving. characters are considered to be at every eighth column. If CH is another control character, it will be drawn in the `C-x' notation. (Calling `winch' after adding a control character will not return the control character, but instead will return the representation of the control character.) Video attributes can be combined with a character by or-ing them into the parameter. This will result in these attributes also being set. The intent here is that text, including attributes, can be copied from one place to another using inch and display. See `standout', below. _Note:_ For `wadd' CH can be an integer and will insert the character of the corresponding value. - Function: werase win This routine copies blanks to every position in the window WIN. - Function: wclear win This routine is like `werase', but it also calls *Note clearok: Output Options Setting, arranging that the screen will be cleared completely on the next call to `refresh' or `force-output' for window WIN, and repainted from scratch. - Function: wclrtobot win All lines below the cursor in window WIN are erased. Also, the current line to the right of the cursor, inclusive, is erased. - Function: wclrtoeol win The current line to the right of the cursor, inclusive, is erased. - Function: wdelch win The character under the cursor in the window WIN is deleted. All characters to the right on the same line are moved to the left one position and the last character on the line is filled with a blank. The cursor position does not change. This does not imply use of the hardware "delete-character" feature. - Function: wdeleteln win The line under the cursor in the window WIN is deleted. All lines below the current line are moved up one line. The bottom line WIN is cleared. The cursor position does not change. This does not imply use of the hardware "deleteline" feature. - Function: winsch win ch The character CH is inserted before the character under the cursor. All characters to the right are moved one to the right, possibly losing the rightmost character of the line. The cursor position does not change . This does not imply use of the hardware "insertcharacter" feature. - Function: winsertln win A blank line is inserted above the current line and the bottom line is lost. This does not imply use of the hardware "insert-line" feature. - Function: scroll win The window WIN is scrolled up one line. This involves moving the lines in WIN's data structure. As an optimization, if WIN is stdscr and the scrolling region is the entire window, the physical screen will be scrolled at the same time.  File: scm.info, Node: Input, Next: Curses Miscellany, Prev: Output, Up: Curses Input ----- - Function: read-char win A character is read from the terminal associated with the window WIN. Depending on the setting of `cbreak', this will be after one character (`CBREAK' mode), or after the first newline (`NOCBREAK' mode). Unless `noecho' has been set, the character will also be echoed into WIN. When using `read-char', do not set both `NOCBREAK' mode (`nocbreak') and `ECHO' mode (`echo') at the same time. Depending on the state of the terminal driver when each character is typed, the program may produce undesirable results. - Function: winch win The character, of type chtype, at the current position in window WIN is returned. If any attributes are set for that position, their values will be OR'ed into the value returned. - Function: getyx win A list of the y and x coordinates of the cursor position of the window WIN is returned  File: scm.info, Node: Curses Miscellany, Prev: Input, Up: Curses Curses Miscellany ----------------- - Function: wstandout win - Function: wstandend win These functions set the current attributes of the window WIN. The current attributes of WIN are applied to all characters that are written into it. Attributes are a property of the character, and move with the character through any scrolling and insert/delete line/character operations. To the extent possible on the particular terminal, they will be displayed as the graphic rendition of characters put on the screen. `wstandout' sets the current attributes of the window WIN to be visibly different from other text. `wstandend' turns off the attributes. - Function: box win vertch horch A box is drawn around the edge of the window WIN. VERTCH and HORCH are the characters the box is to be drawn with. If VERTCH and HORCH are 0, then appropriate default characters, `ACS_VLINE' and `ACS_HLINE', will be used. _Note:_ VERTCH and HORCH can be an integers and will insert the character (with attributes) of the corresponding values. - Function: unctrl c This macro expands to a character string which is a printable representation of the character C. Control characters are displayed in the `C-x' notation. Printing characters are displayed as is.  File: scm.info, Node: Sockets, Prev: Curses, Up: Packages Sockets ======= These procedures (defined in `socket.c') provide a Scheme interface to most of the C "socket" library. For more information on sockets, *Note Sockets: (libc)Sockets. * Menu: * Host Data:: * Internet Addresses and Socket Names:: * Socket::  File: scm.info, Node: Host Data, Next: Internet Addresses and Socket Names, Prev: Sockets, Up: Sockets Host Data, Network, Protocol, and Service Inquiries --------------------------------------------------- - Constant: af_inet - Constant: af_unix Integer family codes for Internet and Unix sockets, respectively. - Function: gethost host-spec - Function: gethost Returns a vector of information for the entry for `HOST-SPEC' or the next entry if `HOST-SPEC' isn't given. The information is: 0. host name string 1. list of host aliases strings 2. integer address type (`AF_INET') 3. integer size of address entries (in bytes) 4. list of integer addresses - Function: sethostent stay-open - Function: sethostent Rewinds the host entry table back to the begining if given an argument. If the argument STAY-OPEN is `#f' queries will be be done using `UDP' datagrams. Otherwise, a connected `TCP' socket will be used. When called without an argument, the host table is closed. - Function: getnet name-or-number - Function: getnet Returns a vector of information for the entry for NAME-OR-NUMBER or the next entry if an argument isn't given. The information is: 0. official network name string 1. list of network aliases strings 2. integer network address type (`AF_INET') 3. integer network number - Function: setnetent stay-open - Function: setnetent Rewinds the network entry table back to the begining if given an argument. If the argument STAY-OPEN is `#f' the table will be closed between calls to getnet. Otherwise, the table stays open. When called without an argument, the network table is closed. - Function: getproto name-or-number - Function: getproto Returns a vector of information for the entry for NAME-OR-NUMBER or the next entry if an argument isn't given. The information is: 1. official protocol name string 2. list of protocol aliases strings 3. integer protocol number - Function: setprotoent stay-open - Function: setprotoent Rewinds the protocol entry table back to the begining if given an argument. If the argument STAY-OPEN is `#f' the table will be closed between calls to getproto. Otherwise, the table stays open. When called without an argument, the protocol table is closed. - Function: getserv name-or-port-number protocol - Function: getserv Returns a vector of information for the entry for NAME-OR-PORT-NUMBER and PROTOCOL or the next entry if arguments aren't given. The information is: 0. official service name string 1. list of service aliases strings 2. integer port number 3. protocol - Function: setservent stay-open - Function: setservent Rewinds the service entry table back to the begining if given an argument. If the argument STAY-OPEN is `#f' the table will be closed between calls to getserv. Otherwise, the table stays open. When called without an argument, the service table is closed.  File: scm.info, Node: Internet Addresses and Socket Names, Next: Socket, Prev: Host Data, Up: Sockets Internet Addresses and Socket Names ----------------------------------- - Function: inet:string->address string Returns the host address number (integer) for host STRING or `#f' if not found. - Function: inet:address->string address Converts an internet (integer) address to a string in numbers and dots notation. - Function: inet:network address Returns the network number (integer) specified from ADDRESS or `#f' if not found. - Function: inet:local-network-address address Returns the integer for the address of ADDRESS within its local network or `#f' if not found. - Function: inet:make-address network local-address Returns the Internet address of LOCAL-ADDRESS in NETWORK. The type "socket-name" is used for inquiries about open sockets in the following procedures: - Function: getsockname socket Returns the socket-name of SOCKET. Returns `#f' if unsuccessful or SOCKET is closed. - Function: getpeername socket Returns the socket-name of the socket connected to SOCKET. Returns `#f' if unsuccessful or SOCKET is closed. - Function: socket-name:family socket-name Returns the integer code for the family of SOCKET-NAME. - Function: socket-name:port-number socket-name Returns the integer port number of SOCKET-NAME. - Function: socket-name:address socket-name Returns the integer Internet address for SOCKET-NAME.  File: scm.info, Node: Socket, Prev: Internet Addresses and Socket Names, Up: Sockets Socket ------ When a port is returned from one of these calls it is unbuffered. This allows both reading and writing to the same port to work. If you want buffered ports you can (assuming sock-port is a socket i/o port): (require 'i/o-extensions) (define i-port (duplicate-port sock-port "r")) (define o-port (duplicate-port sock-port "w")) - Function: make-stream-socket family - Function: make-stream-socket family protocol Returns a `SOCK_STREAM' socket of type FAMILY using PROTOCOL. If FAMILY has the value `AF_INET', `SO_REUSEADDR' will be set. The integer argument PROTOCOL corresponds to the integer protocol numbers returned (as vector elements) from `(getproto)'. If the PROTOCOL argument is not supplied, the default (0) for the specified FAMILY is used. SCM sockets look like ports opened for neither reading nor writing. - Function: make-stream-socketpair family - Function: make-stream-socketpair family protocol Returns a pair (cons) of connected `SOCK_STREAM' (socket) ports of type FAMILY using PROTOCOL. Many systems support only socketpairs of the `af-unix' FAMILY. The integer argument PROTOCOL corresponds to the integer protocol numbers returned (as vector elements) from (getproto). If the PROTOCOL argument is not supplied, the default (0) for the specified FAMILY is used. - Function: socket:shutdown socket how Makes SOCKET no longer respond to some or all operations depending on the integer argument HOW: 0. Further input is disallowed. 1. Further output is disallowed. 2. Further input or output is disallowed. `Socket:shutdown' returns SOCKET if successful, `#f' if not. - Function: socket:connect inet-socket host-number port-number - Function: socket:connect unix-socket pathname Returns SOCKET (changed to a read/write port) connected to the Internet socket on host HOST-NUMBER, port PORT-NUMBER or the Unix socket specified by PATHNAME. Returns `#f' if not successful. - Function: socket:bind inet-socket port-number - Function: socket:bind unix-socket pathname Returns INET-SOCKET bound to the integer PORT-NUMBER or the UNIX-SOCKET bound to new socket in the file system at location PATHNAME. Returns `#f' if not successful. Binding a UNIX-SOCKET creates a socket in the file system that must be deleted by the caller when it is no longer needed (using `delete-file'). - Function: socket:listen socket backlog The bound (*note bind: Socket.) SOCKET is readied to accept connections. The positive integer BACKLOG specifies how many pending connections will be allowed before further connection requests are refused. Returns SOCKET (changed to a read-only port) if successful, `#f' if not. - Function: char-ready? listen-socket The input port returned by a successful call to `socket:listen' can be polled for connections by `char-ready?' (*note char-ready?: Files and Ports.). This avoids blocking on connections by `socket:accept'. - Function: socket:accept socket Accepts a connection on a bound, listening SOCKET. Returns an input/output port for the connection. The following example is not too complicated, yet shows the use of sockets for multiple connections without input blocking. ;;;; Scheme chat server ;;; This program implements a simple `chat' server which accepts ;;; connections from multiple clients, and sends to all clients any ;;; characters received from any client. ;;; To connect to chat `telnet localhost 8001' (require 'socket) (require 'i/o-extensions) (let ((listener-socket (socket:bind (make-stream-socket af_inet) 8001)) (connections '())) (socket:listen listener-socket 5) (do () (#f) (let ((actives (or (apply wait-for-input 5 listener-socket connections) '()))) (cond ((null? actives)) ((memq listener-socket actives) (set! actives (cdr (memq listener-socket actives))) (let ((con (socket:accept listener-socket))) (display "accepting connection from ") (display (getpeername con)) (newline) (set! connections (cons con connections)) (display "connected" con) (newline con)))) (set! connections (let next ((con-list connections)) (cond ((null? con-list) '()) (else (let ((con (car con-list))) (cond ((memq con actives) (let ((c (read-char con))) (cond ((eof-object? c) (display "closing connection from ") (display (getpeername con)) (newline) (close-port con) (next (cdr con-list))) (else (for-each (lambda (con) (file-set-position con 0) (write-char c con) (file-set-position con 0)) connections) (cons con (next (cdr con-list))))))) (else (cons con (next (cdr con-list))))))))))))) You can use `telnet localhost 8001' to connect to the chat server, or you can use a client written in scheme: ;;;; Scheme chat client ;;; this program connects to socket 8001. It then sends all ;;; characters from current-input-port to the socket and sends all ;;; characters from the socket to current-output-port. (require 'socket) (require 'i/o-extensions) (define con (make-stream-socket af_inet)) (set! con (socket:connect con (inet:string->address "localhost") 8001)) (define (go) (define actives (wait-for-input (* 30 60) con (current-input-port))) (let ((cs (and actives (memq con actives) (read-char con))) (ct (and actives (memq (current-input-port) actives) (read-char)))) (cond ((or (eof-object? cs) (eof-object? ct)) (close-port con)) (else (cond (cs (display cs))) (cond (ct (file-set-position con 0) (display ct con) (file-set-position con 0))) (go))))) (cond (con (display "Connecting to ") (display (getpeername con)) (newline) (go)) (else (display "Server not listening on port 8001") (newline)))  File: scm.info, Node: The Implementation, Next: Index, Prev: Packages, Up: Top The Implementation ****************** * Menu: * Data Types:: * Operations:: * Program Self-Knowledge:: What SCM needs to know about itself. * Improvements To Make::  File: scm.info, Node: Data Types, Next: Operations, Prev: The Implementation, Up: The Implementation Data Types ========== In the descriptions below it is assumed that `long int's are 32 bits in length. Acutally, SCM is written to work with any `long int' size larger than 31 bits. With some modification, SCM could work with word sizes as small as 24 bits. All SCM objects are represented by type "SCM". Type `SCM' come in 2 basic flavors, Immediates and Cells: * Menu: * Immediates:: * Cells:: Non-Immediate types * Header Cells:: Malloc objects * Subr Cells:: Built-in and Compiled Procedures * Ptob Cells:: I/O ports * Smob Cells:: Miscellaneous datatypes * Data Type Representations:: How they all fit together  File: scm.info, Node: Immediates, Next: Cells, Prev: Data Types, Up: Data Types Immediates ---------- An "immediate" is a data type contained in type `SCM' (`long int'). The type codes distinguishing immediate types from each other vary in length, but reside in the low order bits. - Macro: IMP x - Macro: NIMP x Return non-zero if the `SCM' object X is an immediate or non-immediate type, respectively. - Immediate: inum immediate 30 bit signed integer. An INUM is flagged by a `1' in the second to low order bit position. The high order 30 bits are used for the integer's value. - Macro: INUMP x - Macro: NINUMP x Return non-zero if the `SCM' X is an immediate integer or not an immediate integer, respectively. - Macro: INUM x Returns the C `long integer' corresponding to `SCM' X. - Macro: MAKINUM x Returns the `SCM' inum corresponding to C `long integer' x. - Immediate Constant: INUM0 is equivalent to `MAKINUM(0)'. Computations on INUMs are performed by converting the arguments to C integers (by a shift), operating on the integers, and converting the result to an inum. The result is checked for overflow by converting back to integer and checking the reverse operation. The shifts used for conversion need to be signed shifts. If the C implementation does not support signed right shift this fact is detected in a #if statement in `scmfig.h' and a signed right shift, `SRS', is constructed in terms of unsigned right shift. - Immediate: ichr characters. - Macro: ICHRP x Return non-zero if the `SCM' object X is a character. - Macro: ICHR x Returns corresponding `unsigned char'. - Macro: MAKICHR x Given `char' X, returns `SCM' character. - Immediate: iflags These are frequently used immediate constants. - Immediate Constant: SCM BOOL_T `#t' - Immediate Constant: SCM BOOL_F `#f' - Immediate Constant: SCM EOL `()'. If `SICP' is `#define'd, `EOL' is `#define'd to be identical with `BOOL_F'. In this case, both print as `#f'. - Immediate Constant: SCM EOF_VAL end of file token, `#'. - Immediate Constant: SCM UNDEFINED `#' used for variables which have not been defined and absent optional arguments. - Immediate Constant: SCM UNSPECIFIED `#' is returned for those procedures whose return values are not specified. - Macro: IFLAGP n Returns non-zero if N is an ispcsym, isym or iflag. - Macro: ISYMP n Returns non-zero if N is an ispcsym or isym. - Macro: ISYMNUM n Given ispcsym, isym, or iflag N, returns its index in the C array `isymnames[]'. - Macro: ISYMCHARS n Given ispcsym, isym, or iflag N, returns its `char *' representation (from `isymnames[]'). - Macro: MAKSPCSYM n Returns `SCM' ispcsym N. - Macro: MAKISYM n Returns `SCM' iisym N. - Macro: MAKIFLAG n Returns `SCM' iflag N. - Variable: isymnames An array of strings containing the external representations of all the ispcsym, isym, and iflag immediates. Defined in `repl.c'. - Constant: NUM_ISPCSYM - Constant: NUM_ISYMS The number of ispcsyms and ispcsyms+isyms, respectively. Defined in `scm.h'. - Immediate: isym `and', `begin', `case', `cond', `define', `do', `if', `lambda', `let', `let*', `letrec', `or', `quote', `set!', `#f', `#t', `#', `#', `()', and `#'. - CAR Immediate: ispcsym special symbols: syntax-checked versions of first 14 isyms - CAR Immediate: iloc indexes to a variable's location in environment - CAR Immediate: gloc pointer to a symbol's value cell - Immediate: CELLPTR pointer to a cell (not really an immediate type, but here for completeness). Since cells are always 8 byte aligned, a pointer to a cell has the low order 3 bits `0'. There is one exception to this rule, _CAR Immediate_s, described next. A "CAR Immediate" is an Immediate point which can only occur in the `CAR's of evaluated code (as a result of `ceval''s memoization process).  File: scm.info, Node: Cells, Next: Header Cells, Prev: Immediates, Up: Data Types Cells ----- "Cell"s represent all SCM objects other than immediates. A cell has a `CAR' and a `CDR'. Low-order bits in `CAR' identify the type of object. The rest of `CAR' and `CDR' hold object data. The number after `tc' specifies how many bits are in the type code. For instance, `tc7' indicates that the type code is 7 bits. - Macro: NEWCELL x Allocates a new cell and stores a pointer to it in `SCM' local variable X. Care needs to be taken that stores into the new cell pointed to by X do not create an inconsistent object. *Note Signals::. All of the C macros decribed in this section assume that their argument is of type `SCM' and points to a cell (`CELLPTR'). - Macro: CAR x - Macro: CDR x Returns the `car' and `cdr' of cell X, respectively. - Macro: TYP3 x - Macro: TYP7 x - Macro: TYP16 x Returns the 3, 7, and 16 bit type code of a cell. - Cell: tc3_cons scheme cons-cell returned by (cons arg1 arg2). - Macro: CONSP x - Macro: NCONSP x Returns non-zero if X is a `tc3_cons' or isn't, respectively. - Cell: tc3_closure applicable object returned by (lambda (args) ...). `tc3_closure's have a pointer to the body of the procedure in the `CAR' and a pointer to the environment in the `CDR'. Bits 1 and 2 (zero-based) in the `CDR' indicate a lower bound on the number of required arguments to the closure, which is used to avoid allocating rest argument lists in the environment cache. This encoding precludes an immediate value for the `CDR': In the case of an empty environment all bits above 2 in the `CDR' are zero. - Macro: CLOSUREP x Returns non-zero if X is a `tc3_closure'. - Macro: CODE x - Macro: ENV x Returns the code body or environment of closure X, respectively. - Macro: ARGC x Returns the a lower bound on the number of required arguments to closure X, it cannot exceed 3.  File: scm.info, Node: Header Cells, Next: Subr Cells, Prev: Cells, Up: Data Types Header Cells ------------ "Header"s are Cells whose `CDR's point elsewhere in memory, such as to memory allocated by `malloc'. - Header: spare spare `tc7' type code - Header: tc7_vector scheme vector. - Macro: VECTORP x - Macro: NVECTORP x Returns non-zero if X is a `tc7_vector' or if not, respectively. - Macro: VELTS x - Macro: LENGTH x Returns the C array of `SCM's holding the elements of vector X or its length, respectively. - Header: tc7_ssymbol static scheme symbol (part of initial system) - Header: tc7_msymbol `malloc'ed scheme symbol (can be GCed) - Macro: SYMBOLP x Returns non-zero if X is a `tc7_ssymbol' or `tc7_msymbol'. - Macro: CHARS x - Macro: UCHARS x - Macro: LENGTH x Returns the C array of `char's or as `unsigned char's holding the elements of symbol X or its length, respectively. - Header: tc7_string scheme string - Macro: STRINGP x - Macro: NSTRINGP x Returns non-zero if X is a `tc7_string' or isn't, respectively. - Macro: CHARS x - Macro: UCHARS x - Macro: LENGTH x Returns the C array of `char's or as `unsigned char's holding the elements of string X or its length, respectively. - Header: tc7_bvect uniform vector of booleans (bit-vector) - Header: tc7_ivect uniform vector of integers - Header: tc7_uvect uniform vector of non-negative integers - Header: tc7_svect uniform vector of short integers - Header: tc7_fvect uniform vector of short inexact real numbers - Header: tc7_dvect uniform vector of double precision inexact real numbers - Header: tc7_cvect uniform vector of double precision inexact complex numbers - Header: tc7_contin applicable object produced by call-with-current-continuation - Header: tc7_specfun subr that is treated specially within the evaluator `apply' and `call-with-current-continuation' are denoted by these objects. Their behavior as functions is built into the evaluator; they are not directly associated with C functions. This is necessary in order to make them properly tail recursive. tc16_cclo is a subtype of tc7_specfun, a cclo is similar to a vector (and is GCed like one), but can be applied as a function: 1. the cclo itself is consed onto the head of the argument list 2. the first element of the cclo is applied to that list. Cclo invocation is currently not tail recursive when given 2 or more arguments. - Function: makcclo proc len makes a closure from the _subr_ PROC with LEN-1 extra locations for `SCM' data. Elements of a CCLO are referenced using `VELTS(cclo)[n]' just as for vectors. - Macro: CCLO_LENGTH cclo Expands to the length of CCLO.  File: scm.info, Node: Subr Cells, Next: Ptob Cells, Prev: Header Cells, Up: Data Types Subr Cells ---------- A "Subr" is a header whose `CDR' points to a C code procedure. Scheme primitive procedures are subrs. Except for the arithmetic `tc7_cxr's, the C code procedures will be passed arguments (and return results) of type `SCM'. - Subr: tc7_asubr associative C function of 2 arguments. Examples are `+', `-', `*', `/', `max', and `min'. - Subr: tc7_subr_0 C function of no arguments. - Subr: tc7_subr_1 C function of one argument. - Subr: tc7_cxr These subrs are handled specially. If inexact numbers are enabled, the `CDR' should be a function which takes and returns type `double'. Conversions are handled in the interpreter. `floor', `ceiling', `truncate', `round', `$sqrt', `$abs', `$exp', `$log', `$sin', `$cos', `$tan', `$asin', `$acos', `$atan', `$sinh', `$cosh', `$tanh', `$asinh', `$acosh', `$atanh', and `exact->inexact' are defined this way. If the `CDR' is `0' (`NULL'), the name string of the procedure is used to control traversal of its list structure argument. `car', `cdr', `caar', `cadr', `cdar', `cddr', `caaar', `caadr', `cadar', `caddr', `cdaar', `cdadr', `cddar', `cdddr', `caaaar', `caaadr', `caadar', `caaddr', `cadaar', `cadadr', `caddar', `cadddr', `cdaaar', `cdaadr', `cdadar', `cdaddr', `cddaar', `cddadr', `cdddar', and `cddddr' are defined this way. - Subr: tc7_subr_3 C function of 3 arguments. - Subr: tc7_subr_2 C function of 2 arguments. - Subr: tc7_rpsubr transitive relational predicate C function of 2 arguments. The C function should return either `BOOL_T' or `BOOL_F'. - Subr: tc7_subr_1o C function of one optional argument. If the optional argument is not present, `UNDEFINED' is passed in its place. - Subr: tc7_subr_2o C function of 1 required and 1 optional argument. If the optional argument is not present, `UNDEFINED' is passed in its place. - Subr: tc7_lsubr_2 C function of 2 arguments and a list of (rest of) `SCM' arguments. - Subr: tc7_lsubr C function of list of `SCM' arguments.  File: scm.info, Node: Ptob Cells, Next: Smob Cells, Prev: Subr Cells, Up: Data Types Ptob Cells ---------- A "ptob" is a port object, capable of delivering or accepting characters. *Note Ports: (r5rs)Ports. Unlike the types described so far, new varieties of ptobs can be defined dynamically (*note Defining Ptobs::). These are the initial ptobs: - ptob: tc16_inport input port. - ptob: tc16_outport output port. - ptob: tc16_ioport input-output port. - ptob: tc16_inpipe input pipe created by `popen()'. - ptob: tc16_outpipe output pipe created by `popen()'. - ptob: tc16_strport String port created by `cwos()' or `cwis()'. - ptob: tc16_sfport Software (virtual) port created by `mksfpt()' (*note Soft Ports::). - Macro: PORTP x - Macro: OPPORTP x - Macro: OPINPORTP x - Macro: OPOUTPORTP x - Macro: INPORTP x - Macro: OUTPORTP x Returns non-zero if X is a port, open port, open input-port, open output-port, input-port, or output-port, respectively. - Macro: OPENP x - Macro: CLOSEDP x Returns non-zero if port X is open or closed, respectively. - Macro: STREAM x Returns the `FILE *' stream for port X. Ports which are particularly well behaved are called "fport"s. Advanced operations like `file-position' and `reopen-file' only work for fports. - Macro: FPORTP x - Macro: OPFPORTP x - Macro: OPINFPORTP x - Macro: OPOUTFPORTP x Returns non-zero if X is a port, open port, open input-port, or open output-port, respectively.  File: scm.info, Node: Smob Cells, Next: Data Type Representations, Prev: Ptob Cells, Up: Data Types Smob Cells ---------- A "smob" is a miscellaneous datatype. The type code and GCMARK bit occupy the lower order 16 bits of the `CAR' half of the cell. The rest of the `CAR' can be used for sub-type or other information. The `CDR' contains data of size long and is often a pointer to allocated memory. Like ptobs, new varieties of smobs can be defined dynamically (*note Defining Smobs::). These are the initial smobs: - smob: tc_free_cell unused cell on the freelist. - smob: tc16_flo single-precision float. Inexact number data types are subtypes of type `tc16_flo'. If the sub-type is: 0. a single precision float is contained in the `CDR'. 1. `CDR' is a pointer to a `malloc'ed double. 3. `CDR' is a pointer to a `malloc'ed pair of doubles. - smob: tc_dblr double-precision float. - smob: tc_dblc double-precision complex. - smob: tc16_bigpos - smob: tc16_bigneg positive and negative bignums, respectively. Scm has large precision integers called bignums. They are stored in sign-magnitude form with the sign occuring in the type code of the SMOBs bigpos and bigneg. The magnitude is stored as a `malloc'ed array of type `BIGDIG' which must be an unsigned integral type with size smaller than `long'. `BIGRAD' is the radix associated with `BIGDIG'. `NUMDIGS_MAX' (defined in `scmfig.h') limits the number of digits of a bignum to 1000. These digits are base `BIGRAD', which is typically 65536, giving 4816 decimal digits. Why only 4800 digits? The simple multiplication algorithm SCM uses is O(n^2); this means the number of processor instructions required to perform a multiplication is _some multiple_ of the product of the number of digits of the two multiplicands. digits * digits ==> operations 5 x 50 100 * x 500 10000 * x 5000 1000000 * x To calculate numbers larger than this, FFT multiplication [O(n*log(n))] and other specialized algorithms are required. You should obtain a package which specializes in number-theoretical calculations: - smob: tc16_promise made by DELAY. *Note Control features: (r5rs)Control features. - smob: tc16_arbiter synchronization object. *Note Process Synchronization::. - smob: tc16_macro macro expanding function. *Note Low Level Syntactic Hooks::. - smob: tc16_array multi-dimensional array. *Note Arrays::. This type implements both conventional arrays (those with arbitrary data as elements *note Conventional Arrays::) and uniform arrays (those with elements of a uniform type *note Uniform Array::). Conventional Arrays have a pointer to a vector for their `CDR'. Uniform Arrays have a pointer to a Uniform Vector type (string, bvect, ivect, uvect, fvect, dvect, or cvect) in their `CDR'.  File: scm.info, Node: Data Type Representations, Prev: Smob Cells, Up: Data Types Data Type Representations ------------------------- IMMEDIATE: B,D,E,F=data bit, C=flag code, P=pointer address bit ................................ inum BBBBBBBBBBBBBBBBBBBBBBBBBBBBBB10 ichr BBBBBBBBBBBBBBBBBBBBBBBB11110100 iflag CCCCCCC101110100 isym CCCCCCC001110100 IMCAR: only in car of evaluated code, cdr has cell's GC bit ispcsym 000CCCC00CCCC100 iloc 0DDDDDDDDDDDEFFFFFFFFFFF11111100 pointer PPPPPPPPPPPPPPPPPPPPPPPPPPPPP000 gloc PPPPPPPPPPPPPPPPPPPPPPPPPPPPP001 HEAP CELL: G=gc_mark; 1 during mark, 0 other times. 1s and 0s here indicate type. G missing means sys (not GC'd) SIMPLE: cons ..........SCM car..............0 ...........SCM cdr.............G closure ..........SCM code...........011 ...........SCM env...........CCG HEADERs: ssymbol .........long length....G0000101 ..........char *chars........... msymbol .........long length....G0000111 ..........char *chars........... string .........long length....G0001101 ..........char *chars........... vector .........long length....G0001111 ...........SCM **elts........... bvect .........long length....G0010101 ..........long *words........... spare G0010111 ivect .........long length....G0011101 ..........long *words........... uvect .........long length....G0011111 ......unsigned long *words...... spare G0100101 svect .........long length....G0100111 ........ short *words........... fvect .........long length....G0101101 .........float *words........... dvect .........long length....G0101111 ........double *words........... cvect .........long length....G0110101 ........double *words........... contin .........long length....G0111101 .............*regs.............. specfun ................xxxxxxxxG1111111 ...........SCM name............. cclo ..short length..xxxxxx10G1111111 ...........SCM **elts........... PTOBs: port 0bwroxxxxxxxxG0110111 ..........FILE *stream.......... socket ttttttt 00001xxxxxxxxG0110111 ..........FILE *stream.......... inport uuuuuuuuuuU00011xxxxxxxxG0110111 ..........FILE *stream.......... outport 0000000000000101xxxxxxxxG0110111 ..........FILE *stream.......... ioport uuuuuuuuuuU00111xxxxxxxxG0110111 ..........FILE *stream.......... fport 00 00000000G0110111 ..........FILE *stream.......... pipe 00 00000001G0110111 ..........FILE *stream.......... strport 00 00000010G0110111 ..........FILE *stream.......... sfport 00 00000011G0110111 ..........FILE *stream.......... SUBRs: spare 010001x1 spare 010011x1 subr_0 ..........int hpoff.....01010101 ...........SCM (*f)()........... subr_1 ..........int hpoff.....01010111 ...........SCM (*f)()........... cxr ..........int hpoff.....01011101 .........double (*f)().......... subr_3 ..........int hpoff.....01011111 ...........SCM (*f)()........... subr_2 ..........int hpoff.....01100101 ...........SCM (*f)()........... asubr ..........int hpoff.....01100111 ...........SCM (*f)()........... subr_1o ..........int hpoff.....01101101 ...........SCM (*f)()........... subr_2o ..........int hpoff.....01101111 ...........SCM (*f)()........... lsubr_2 ..........int hpoff.....01110101 ...........SCM (*f)()........... lsubr ..........int hpoff.....01110111 ...........SCM (*f)()........... rpsubr ..........int hpoff.....01111101 ...........SCM (*f)()........... SMOBs: free_cell 000000000000000000000000G1111111 ...........*free_cell........000 flo 000000000000000000000001G1111111 ...........float num............ dblr 000000000000000100000001G1111111 ..........double *real.......... dblc 000000000000001100000001G1111111 .........complex *cmpx.......... bignum ...int length...0000001 G1111111 .........short *digits.......... bigpos ...int length...00000010G1111111 .........short *digits.......... bigneg ...int length...00000011G1111111 .........short *digits.......... xxxxxxxx = code assigned by newsmob(); promise 000000000000000fxxxxxxxxG1111111 ...........SCM val.............. arbiter 000000000000000lxxxxxxxxG1111111 ...........SCM name............. macro 000000000000000mxxxxxxxxG1111111 ...........SCM name............. array ...short rank..cxxxxxxxxG1111111 ............*array..............  File: scm.info, Node: Operations, Next: Program Self-Knowledge, Prev: Data Types, Up: The Implementation Operations ========== * Menu: * Garbage Collection:: Automatically reclaims unused storage * Memory Management for Environments:: * Signals:: * C Macros:: * Changing Scm:: * Defining Subrs:: * Defining Smobs:: * Defining Ptobs:: * Allocating memory:: * Embedding SCM:: In other programs * Callbacks:: * Type Conversions:: For use with C code. * Continuations:: For C and SCM * Evaluation:: Why SCM is fast  File: scm.info, Node: Garbage Collection, Next: Memory Management for Environments, Prev: Operations, Up: Operations Garbage Collection ------------------ The garbage collector is in the latter half of `sys.c'. The primary goal of "garbage collection" (or "GC") is to recycle those cells no longer in use. Immediates always appear as parts of other objects, so they are not subject to explicit garbage collection. All cells reside in the "heap" (composed of "heap segments"). Note that this is different from what Computer Science usually defines as a heap. * Menu: * Marking Cells:: * Sweeping the Heap::  File: scm.info, Node: Marking Cells, Next: Sweeping the Heap, Prev: Garbage Collection, Up: Garbage Collection Marking Cells ............. The first step in garbage collection is to "mark" all heap objects in use. Each heap cell has a bit reserved for this purpose. For pairs (cons cells) the lowest order bit (0) of the CDR is used. For other types, bit 8 of the CAR is used. The GC bits are never set except during garbage collection. Special C macros are defined in `scm.h' to allow easy manipulation when GC bits are possibly set. `CAR', `TYP3', and `TYP7' can be used on GC marked cells as they are. - Macro: GCCDR x Returns the CDR of a cons cell, even if that cell has been GC marked. - Macro: GCTYP16 x Returns the 16 bit type code of a cell. We need to (recursively) mark only a few objects in order to assure that all accessible objects are marked. Those objects are `sys_protects[]' (for example, `dynwinds'), the current C-stack and the hash table for symbols, "symhash". - Function: void gc_mark (SCM OBJ) The function `gc_mark()' is used for marking SCM cells. If OBJ is marked, `gc_mark()' returns. If OBJ is unmarked, gc_mark sets the mark bit in OBJ, then calls `gc_mark()' on any SCM components of OBJ. The last call to `gc_mark()' is tail-called (looped). - Function: void mark_locations (STACKITEM X[], sizet LEN)) The function `mark_locations' is used for marking segments of C-stack or saved segments of C-stack (marked continuations). The argument LEN is the size of the stack in units of size `(STACKITEM)'. Each longword in the stack is tried to see if it is a valid cell pointer into the heap. If it is, the object itself and any objects it points to are marked using `gc_mark'. If the stack is word rather than longword aligned `(#define WORD_ALIGN)', both alignments are tried. This arrangement will occasionally mark an object which is no longer used. This has not been a problem in practice and the advantage of using the c-stack far outweighs it.  File: scm.info, Node: Sweeping the Heap, Prev: Marking Cells, Up: Garbage Collection Sweeping the Heap ................. After all found objects have been marked, the heap is swept. The storage for strings, vectors, continuations, doubles, complexes, and bignums is managed by malloc. There is only one pointer to each malloc object from its type-header cell in the heap. This allows malloc objects to be freed when the associated heap object is garbage collected. - Function: static void gc_sweep () The function `gc_sweep' scans through all heap segments. The mark bit is cleared from marked cells. Unmarked cells are spliced into FREELIST, where they can again be returned by invocations of `NEWCELL'. If a type-header cell pointing to malloc space is unmarked, the malloc object is freed. If the type header of smob is collected, the smob's `free' procedure is called to free its storage.  File: scm.info, Node: Memory Management for Environments, Next: Signals, Prev: Garbage Collection, Up: Operations Memory Management for Environments ---------------------------------- * "Ecache" was designed and implemented by Radey Shouman. * This documentation of ecache was written by Tom Lord. The memory management component of SCM contains special features which optimize the allocation and garbage collection of environments. The optimizations are based on certain facts and assumptions: The SCM evaluator creates many environments with short lifetimes and these account of a _large portion_ of the total number of objects allocated. The general purpose allocator allocates objects from a freelist, and collects using a mark/sweep algorithm. Research into garbage collection suggests that such an allocator is sub-optimal for object populations containing a large portion of short-lived members and that allocation strategies involving a copying collector are more appropriate. It is a property of SCM, reflected throughout the source code, that a simple copying collector can not be used as the general purpose memory manager: much code assumes that the run-time stack can be treated as a garbage collection root set using "conservative garbage collection" techniques, which are incompatible with objects that change location. Nevertheless, it is possible to use a mostly-separate copying-collector, just for environments. Roughly speaking, cons pairs making up environments are initially allocated from a small heap that is collected by a precise copying collector. These objects must be handled specially for the collector to work. The (presumably) small number of these objects that survive one collection of the copying heap are copied to the general purpose heap, where they will later be collected by the mark/sweep collector. The remaining pairs are more rapidly collected than they would otherwise be and all of this collection is accomplished without having to mark or sweep any other segment of the heap. Allocating cons pairs for environments from this special heap is a heuristic that approximates the (unachievable) goal: allocate all short-lived objects from the copying-heap, at no extra cost in allocation time. Implementation Details ...................... A separate heap (`ecache_v') is maintained for the copying collector. Pairs are allocated from this heap in a stack-like fashion. Objects in this heap may be protected from garbage collection by: 1. Pushing a reference to the object on a stack specially maintained for that purpose. This stack (`scm_estk') is used in place of the C run-time stack by the SCM evaluator to hold local variables which refer to the copying heap. 2. Saving a reference to every object in the mark/sweep heap which directly references the copying heap in a root set that is specially maintained for that purpose (`scm_egc_roots'). If no object in the mark/sweep heap directly references an object from the copying heap, that object can be preserved by storing a direct reference to it in the copying-collector root set. 3. Keeping no other references to these objects, except references between the objects themselves, during copying collection. When the copying heap or root-set becomes full, the copying collector is invoked. All protected objects are copied to the mark-sweep heap. All references to those objects are updated. The copying collector root-set and heap are emptied. References to pairs allocated specificly for environments are inaccessible to the Scheme procedures evaluated by SCM. These pairs are manipulated by only a small number of code fragments in the interpreter. To support copying collection, those code fragments (mostly in `eval.c') have been modified to protect environments from garbage collection using the three rules listed above. During a mark-sweep collection, the copying collector heap is marked and swept almost like any ordinary segment of the general purpose heap. The only difference is that pairs from the copying heap that become free during a sweep phase are not added to the freelist. The environment cache is disabled by adding `#define NO_ENV_CACHE' to `eval.c'; all environment cells are then allocated from the regular heap. Relation to Other Work ...................... This work seems to build upon a considerable amount of previous work into garbage collection techniques about which a considerable amount of literature is available.  File: scm.info, Node: Signals, Next: C Macros, Prev: Memory Management for Environments, Up: Operations Signals ------- - Function: init_signals (in `scm.c') initializes handlers for `SIGINT' and `SIGALRM' if they are supported by the C implementation. All of the signal handlers immediately reestablish themselves by a call to `signal()'. - Function: int_signal sig - Function: alrm_signal sig The low level handlers for `SIGINT' and `SIGALRM'. If an interrupt handler is defined when the interrupt is received, the code is interpreted. If the code returns, execution resumes from where the interrupt happened. `Call-with-current-continuation' allows the stack to be saved and restored. SCM does not use any signal masking system calls. These are not a portable feature. However, code can run uninterrupted by use of the C macros `DEFER_INTS' and `ALLOW_INTS'. - Macro: DEFER_INTS sets the global variable `ints_disabled' to 1. If an interrupt occurs during a time when `ints_disabled' is 1, then `deferred_proc' is set to non-zero, one of the global variables `SIGINT_deferred' or `SIGALRM_deferred' is set to 1, and the handler returns. - Macro: ALLOW_INTS Checks the deferred variables and if set the appropriate handler is called. Calls to `DEFER_INTS' can not be nested. An `ALLOW_INTS' must happen before another `DEFER_INTS' can be done. In order to check that this constraint is satisfied `#define CAREFUL_INTS' in `scmfig.h'.  File: scm.info, Node: C Macros, Next: Changing Scm, Prev: Signals, Up: Operations C Macros -------- - Macro: ASSERT cond arg pos subr signals an error if the expression (COND) is 0. ARG is the offending object, SUBR is the string naming the subr, and POS indicates the position or type of error. POS can be one of * `ARGn' (> 5 or unknown ARG number) * `ARG1' * `ARG2' * `ARG3' * `ARG4' * `ARG5' * `WNA' (wrong number of args) * `OVFLOW' * `OUTOFRANGE' * `NALLOC' * `EXIT' * `HUP_SIGNAL' * `INT_SIGNAL' * `FPE_SIGNAL' * `BUS_SIGNAL' * `SEGV_SIGNAL' * `ALRM_SIGNAL' * a C string `(char *)' Error checking is not done by `ASSERT' if the flag `RECKLESS' is defined. An error condition can still be signaled in this case with a call to `wta(arg, pos, subr)'. - Macro: ASRTGO cond label `goto' LABEL if the expression (COND) is 0. Like `ASSERT', `ASRTGO' does is not active if the flag `RECKLESS' is defined.  File: scm.info, Node: Changing Scm, Next: Defining Subrs, Prev: C Macros, Up: Operations Changing Scm ------------ When writing C-code for SCM, a precaution is recommended. If your routine allocates a non-cons cell which will _not_ be incorporated into a `SCM' object which is returned, you need to make sure that a `SCM' variable in your routine points to that cell as long as part of it might be referenced by your code. In order to make sure this `SCM' variable does not get optimized out you can put this assignment after its last possible use: SCM_dummy1 = foo; or put this assignment somewhere in your routine: SCM_dummy1 = (SCM) &foo; `SCM_dummy' variables are not currently defined. Passing the address of the local `SCM' variable to _any_ procedure also protects it. The procedure `scm_protect_temp' is provided for this purpose. Also, if you maintain a static pointer to some (non-immediate) `SCM' object, you must either make your pointer be the value cell of a symbol (see `errobj' for an example) or make your pointer be one of the `sys_protects' (see `dynwinds' for an example). The former method is prefered since it does not require any changes to the SCM distribution. To add a C routine to scm: 1. choose the appropriate subr type from the type list. 2. write the code and put into `scm.c'. 3. add a `make_subr' or `make_gsubr' call to `init_scm'. Or put an entry into the appropriate `iproc' structure. To add a package of new procedures to scm (see `crs.c' for example): 1. create a new C file (`foo.c'). 2. at the front of `foo.c' put declarations for strings for your procedure names. static char s_twiddle_bits[]="twiddle-bits!"; static char s_bitsp[]="bits?"; 3. choose the appropriate subr types from the type list in `code.doc'. 4. write the code for the procedures and put into `foo.c' 5. create one `iproc' structure for each subr type used in `foo.c' static iproc subr3s[]= { {s_twiddle-bits,twiddle-bits}, {s_bitsp,bitsp}, {0,0} }; 6. create an `init_' routine at the end of the file which calls `init_iprocs' with the correct type for each of the `iproc's created in step 5. void init_foo() { init_iprocs(subr1s, tc7_subr_1); init_iprocs(subr3s, tc7_subr_3); } If your package needs to have a "finalization" routine called to free up storage, close files, etc, then also have a line in `init_foo' like: add_final(final_foo); `final_foo' should be a (void) procedure of no arguments. The finals will be called in opposite order from their definition. The line: add_feature("foo"); will append a symbol `'foo' to the (list) value of `*features*'. 7. put any scheme code which needs to be run as part of your package into `Ifoo.scm'. 8. put an `if' into `Init5d6.scm' which loads `Ifoo.scm' if your package is included: (if (defined? twiddle-bits!) (load (in-vicinity (implementation-vicinity) "Ifoo" (scheme-file-suffix)))) or use `(provided? 'foo)' instead of `(defined? twiddle-bits!)' if you have added the feature. 9. put documentation of the new procedures into `foo.doc' 10. add lines to your `Makefile' to compile and link SCM with your object file. Add a `init_foo\(\)\;' to the `INITS=...' line at the beginning of the makefile. These steps should allow your package to be linked into SCM with a minimum of difficulty. Your package should also work with dynamic linking if your SCM has this capability. Special forms (new syntax) can be added to scm. 1. define a new `MAKISYM' in `scm.h' and increment `NUM_ISYMS'. 2. add a string with the new name in the corresponding place in `isymnames' in `repl.c'. 3. add `case:' clause to `ceval()' near `i_quasiquote' (in `eval.c'). New syntax can now be added without recompiling SCM by the use of the `procedure->syntax', `procedure->macro', `procedure->memoizing-macro', and `defmacro'. For details, *Note Syntax Extensions::.  File: scm.info, Node: Defining Subrs, Next: Defining Smobs, Prev: Changing Scm, Up: Operations Defining Subrs -------------- If "CCLO" is `#define'd when compiling, the compiled closure feature will be enabled. It is automatically enabled if dynamic linking is enabled. The SCM interpreter directly recognizes subrs taking small numbers of arguments. In order to create subrs taking larger numbers of arguments use: - Function: make_gsubr name req opt rest fcn returns a cclo (compiled closure) object of name `char *' NAME which takes `int' REQ required arguments, `int' OPT optional arguments, and a list of rest arguments if `int' REST is 1 (0 for not). `SCM (*fcn)()' is a pointer to a C function to do the work. The C function will always be called with REQ + OPT + REST arguments, optional arguments not supplied will be passed `UNDEFINED'. An error will be signaled if the subr is called with too many or too few arguments. Currently a total of 10 arguments may be specified, but increasing this limit should not be difficult. /* A silly example, taking 2 required args, 1 optional, and a list of rest args */ #include SCM gsubr_21l(req1,req2,opt,rst) SCM req1,req2,opt,rst; { lputs("gsubr-2-1-l:\n req1: ", cur_outp); display(req1,cur_outp); lputs("\n req2: ", cur_outp); display(req2,cur_outp); lputs("\n opt: ", cur_outp); display(opt,cur_outp); lputs("\n rest: ", cur_outp); display(rst,cur_outp); newline(cur_outp); return UNSPECIFIED; } void init_gsubr211() { make_gsubr("gsubr-2-1-l", 2, 1, 1, gsubr_21l); }  File: scm.info, Node: Defining Smobs, Next: Defining Ptobs, Prev: Defining Subrs, Up: Operations Defining Smobs -------------- Here is an example of how to add a new type named `foo' to SCM. The following lines need to be added to your code: `long tc16_foo;' The type code which will be used to identify the new type. `static smobfuns foosmob = {markfoo,freefoo,printfoo,equalpfoo};' smobfuns is a structure composed of 4 functions: typedef struct { SCM (*mark)P((SCM)); sizet (*free)P((CELLPTR)); int (*print)P((SCM exp, SCM port, int writing)); SCM (*equalp)P((SCM, SCM)); } smobfuns; `smob.mark' is a function of one argument of type `SCM' (the cell to mark) and returns type `SCM' which will then be marked. If no further objects need to be marked then return an immediate object such as `BOOL_F'. The smob cell itself will already have been marked. _Note:_ This is different from SCM versions prior to 5c5. Only additional data specific to a smob type need be marked by `smob.mark'. 2 functions are provided: `markcdr(ptr)' returns `CDR(ptr)'. `mark0(ptr)' is a no-op used for smobs containing no additional `SCM' data. 0 may also be used in this case. `smob.free' is a function of one argument of type `CELLPTR' (the cell to collected) and returns type `sizet' which is the number of `malloc'ed bytes which were freed. `Smob.free' should free any `malloc'ed storage associated with this object. The function free0(ptr) is provided which does not free any storage and returns 0. `smob.print' is 0 or a function of 3 arguments. The first, of type `SCM', is the smob object. The second, of type `SCM', is the stream on which to write the result. The third, of type int, is 1 if the object should be `write'n, 0 if it should be `display'ed, and 2 if it should be `write'n for an error report. This function should return non-zero if it printed, and zero otherwise (in which case a hexadecimal number will be printed). `smob.equalp' is 0 or a function of 2 `SCM' arguments. Both of these arguments will be of type `tc16foo'. This function should return `BOOL_T' if the smobs are equal, `BOOL_F' if they are not. If `smob.equalp' is 0, `equal?' will return `BOOL_F' if they are not `eq?'. `tc16_foo = newsmob(&foosmob);' Allocates the new type with the functions from `foosmob'. This line goes in an `init_' routine. Promises and macros in `eval.c' and arbiters in `repl.c' provide examples of SMOBs. There are a maximum of 256 SMOBs. Smobs that must allocate blocks of memory should use, for example, `must_malloc' rather than `malloc' *Note Allocating memory::.  File: scm.info, Node: Defining Ptobs, Next: Allocating memory, Prev: Defining Smobs, Up: Operations Defining Ptobs -------------- "ptob"s are similar to smobs but define new types of port to which SCM procedures can read or write. The following functions are defined in the `ptobfuns': typedef struct { SCM (*mark)P((SCM ptr)); int (*free)P((FILE *p)); int (*print)P((SCM exp, SCM port, int writing)); SCM (*equalp)P((SCM, SCM)); int (*fputc)P((int c, FILE *p)); int (*fputs)P((char *s, FILE *p)); sizet (*fwrite)P((char *s, sizet siz, sizet num, FILE *p)); int (*fflush)P((FILE *stream)); int (*fgetc)P((FILE *p)); int (*fclose)P((FILE *p)); } ptobfuns; The `.free' component to the structure takes a `FILE *' or other C construct as its argument, unlike `.free' in a smob, which takes the whole smob cell. Often, `.free' and `.fclose' can be the same function. See `fptob' and `pipob' in `sys.c' for examples of how to define ptobs. Ptobs that must allocate blocks of memory should use, for example, `must_malloc' rather than `malloc' *Note Allocating memory::.  File: scm.info, Node: Allocating memory, Next: Embedding SCM, Prev: Defining Ptobs, Up: Operations Allocating memory ----------------- SCM maintains a count of bytes allocated using malloc, and calls the garbage collector when that number exceeds a dynamically managed limit. In order for this to work properly, `malloc' and `free' should not be called directly to manage memory freeable by garbage collection. The following functions are provided for that purpose: - Function: SCM must_malloc_cell (long LEN, SCM C, char *WHAT) - Function: char * must_malloc (long LEN, char *WHAT) LEN is the number of bytes that should be allocated, WHAT is a string to be used in error or gc messages. `must_malloc' returns a pointer to newly allocated memory. `must_malloc_cell' returns a newly allocated cell whose `car' is C and whose `cdr' is a pointer to newly allocated memory. - Function: void must_realloc_cell (SCM Z, long OLEN, long LEN, char *WHAT) - Function: char * must_realloc (char *WHERE, long OLEN, long LEN, char *WHAT) `must_realloc_cell' takes as argument Z a cell whose `cdr' should be a pointer to a block of memory of length OLEN allocated with `must_malloc_cell' and modifies the `cdr' to point to a block of memory of length LEN. `must_realloc' takes as argument WHERE the address of a block of memory of length OLEN allocated by `must_malloc' and returns the address of a block of length LEN. The contents of the reallocated block will be unchanged up to the minimum of the old and new sizes. WHAT is a pointer to a string used for error and gc messages. `must_malloc', `must_malloc_cell', `must_realloc', and `must_realloc_cell' must be called with interrupts deferred *Note Signals::. `must_realloc' and `must_realloc_cell' must not be called during initialization (non-zero errjmp_bad) - the initial allocations must be large enough. - Function: void must_free (char *PTR, sizet LEN) `must_free' is used to free a block of memory allocated by the above functions and pointed to by PTR. LEN is the length of the block in bytes, but this value is used only for debugging purposes. If it is difficult or expensive to calculate then zero may be used instead.  File: scm.info, Node: Embedding SCM, Next: Callbacks, Prev: Allocating memory, Up: Operations Embedding SCM ------------- The file `scmmain.c' contains the definition of main(). When SCM is compiled as a library `scmmain.c' is not included in the library; a copy of `scmmain.c' can be modified to use SCM as an embedded library module. - Function: int main (int ARGC, char **ARGV) This is the top level C routine. The value of the ARGC argument is the number of command line arguments. The ARGV argument is a vector of C strings; its elements are the individual command line argument strings. A null pointer always follows the last element: `ARGV[ARGC]' is this null pointer. - Variable: char *execpath This string is the pathname of the executable file being run. This variable can be examined and set from Scheme (*note Internal State::). EXECPATH must be set to executable's path in order to use DUMP (*note Dump::) or DLD. Rename main() and arrange your code to call it with an ARGV which sets up SCM as you want it. If you need more control than is possible through ARGV, here are descriptions of the functions which main() calls. - Function: void init_sbrk (void) Call this before SCM calls malloc(). Value returned from sbrk() is used to gauge how much storage SCM uses. - Function: char * scm_find_execpath (int ARGC, char **ARGV, char *SCRIPT_ARG) ARGC and ARGV are as described in main(). SCRIPT_ARG is the pathname of the SCSH-style script (*note Scripting::) being invoked; 0 otherwise. `scm_find_execpath' returns the pathname of the executable being run; if `scm_find_execpath' cannot determine the pathname, then it returns 0. `scm_find_implpath' is defined in `scmmain.c'. Preceeding this are definitions ofGENERIC_NAME and INIT_GETENV. These, along with IMPLINIT and DIRSEP control scm_find_implpath()'s operation. If your application has an easier way to locate initialization code for SCM, then you can replace `scm_find_implpath'. - Function: char * scm_find_implpath (char *EXECPATH) Returns the full pathname of the Scheme initialization file or 0 if it cannot find it. The string value of the preprocessor variable INIT_GETENV names an environment variable (default `"SCM_INIT_PATH"'). If this environment variable is defined, its value will be returned from `scm_find_implpath'. Otherwise find_impl_file() is called with the arguments EXECPATH, GENERIC_NAME (default "scm"), INIT_FILE_NAME (default "Init5d6_scm"), and the directory separator string DIRSEP. If find_impl_file() returns 0 and IMPLINIT is defined, then a copy of the string IMPLINIT is returned. - Function: int init_buf0 (FILE *INPORT) Tries to determine whether INPORT (usually stdin) is an interactive input port which should be used in an unbuffered mode. If so, INPORT is set to unbuffered and non-zero is returned. Otherwise, 0 is returned. `init_buf0' should be called before any input is read from INPORT. Its value can be used as the last argument to scm_init_from_argv(). - Function: void scm_init_from_argv (int ARGC, char **ARGV, char *SCRIPT_ARG, int IVERBOSE, int BUF0STDIN) Initializes SCM storage and creates a list of the argument strings PROGRAM-ARGUMENTS from ARGV. ARGC and ARGV must already be processed to accomodate Scheme Scripts (if desired). The scheme variable *SCRIPT* is set to the string SCRIPT_ARG, or #f if SCRIPT_ARG is 0. IVERBOSE is the initial prolixity level. If BUF0STDIN is non-zero, stdin is treated as an unbuffered port. Call `init_signals' and `restore_signals' only if you want SCM to handle interrupts and signals. - Function: void init_signals (void) Initializes handlers for `SIGINT' and `SIGALRM' if they are supported by the C implementation. All of the signal handlers immediately reestablish themselves by a call to `signal()'. - Function: void restore_signals (void) Restores the handlers in effect when `init_signals' was called. - Function: SCM scm_top_level (char *INITPATH, SCM (*toplvl_fun)()) This is SCM's top-level. Errors longjmp here. TOPLVL_FUN is a callback function of zero arguments that is called by `scm_top_level' to do useful work - if zero, then `repl', which implements a read-eval-print loop, is called. If TOPLVL_FUN returns, then `scm_top_level' will return as well. If the return value of TOPLVL_FUN is an immediate integer then it will be used as the return value of `scm_top_level'. In the main function supplied with SCM, this return value is the exit status of the process. If the first character of string INITPATH is `;', `(' or whitespace, then scm_ldstr() is called with INITPATH to initialize SCM; otherwise INITPATH names a file of Scheme code to be loaded to initialize SCM. When a Scheme error is signaled; control will pass into `scm_top_level' by `longjmp', error messages will be printed to `current-error-port', and then TOPLVL_FUN will be called again. TOPLVL_FUN must maintain enough state to prevent errors from being resignalled. If `toplvl_fun' can not recover from an error situation it may simply return. - Function: void final_scm (int FREEALL) Calls all finalization routines registered with add_final(). If FREEALL is non-zero, then all memory which SCM allocated with malloc() will be freed. You can call indivdual Scheme procedures from C code in the TOPLVL_FUN argument passed to scm_top_level(), or from module subrs (registered by an `init_' function, *note Changing Scm::). Use `apply' to call Scheme procedures from your C code. For example: /* If this apply fails, SCM will catch the error */ apply(CDR(intern("srv:startup",sizeof("srv:startup")-1)), mksproc(srvproc), listofnull); func = CDR(intern(rpcname,strlen(rpcname))); retval = apply(func, cons(mksproc(srvproc), args), EOL); Functions for loading Scheme files and evaluating Scheme code given as C strings are described in the next section, (*note Callbacks::). Here is a minimal embedding program `libtest.c': /* gcc -o libtest libtest.c libscm.a -ldl -lm -lc */ #include "scm.h" /* include patchlvl.h for SCM's INIT_FILE_NAME. */ #include "patchlvl.h" void init_user_scm() { fputs("This is init_user_scm\n", stderr); fflush(stderr); sysintern("*the-string*", makfrom0str("hello world\n")); } SCM user_main() { static int done = 0; if (done++) return MAKINUM(EXIT_FAILURE); scm_ldstr("(display *the-string*)"); return MAKINUM(EXIT_SUCCESS); } int main(argc, argv) int argc; char **argv; { SCM retval; char *implpath, *execpath; execpath = dld_find_executable(argv[0]); fprintf(stderr, "dld_find_executable(%s): %s\n", argv[0], execpath); implpath = find_impl_file(execpath, "scm", INIT_FILE_NAME, dirsep); fprintf(stderr, "implpath: %s\n", implpath); scm_init_from_argv(argc, argv, 0L, 0, 0); retval = scm_top_level(implpath, user_main); final_scm(!0); return (int)INUM(retval); } -| dld_find_executable(./libtest): /home/jaffer/scm/libtest implpath: /home/jaffer/scm/Init5d6.scm This is init_user_scm hello world  File: scm.info, Node: Callbacks, Next: Type Conversions, Prev: Embedding SCM, Up: Operations Callbacks --------- SCM now has routines to make calling back to Scheme procedures easier. The source code for these routines are found in `rope.c'. - Function: int scm_ldfile (char *FILE) Loads the Scheme source file FILE. Returns 0 if successful, non-0 if not. This function is used to load SCM's initialization file `Init5d6.scm'. - Function: int scm_ldprog (char *FILE) Loads the Scheme source file `(in-vicinity (program-vicinity) FILE)'. Returns 0 if successful, non-0 if not. This function is useful for compiled code init_ functions to load non-compiled Scheme (source) files. `program-vicinity' is the directory from which the calling code was loaded (*note Vicinity: (slib)Vicinity.). - Function: SCM scm_evstr (char *STR) Returns the result of reading an expression from STR and evaluating it. - Function: void scm_ldstr (char *STR) Reads and evaluates all the expressions from STR. If you wish to catch errors during execution of Scheme code, then you can use a wrapper like this for your Scheme procedures: (define (srv:protect proc) (lambda args (define result #f) ; put default value here (call-with-current-continuation (lambda (cont) (dynamic-wind (lambda () #t) (lambda () (set! result (apply proc args)) (set! cont #f)) (lambda () (if cont (cont #f)))))) result)) Calls to procedures so wrapped will return even if an error occurs.  File: scm.info, Node: Type Conversions, Next: Continuations, Prev: Callbacks, Up: Operations Type Conversions ---------------- These type conversion functions are very useful for connecting SCM and C code. Most are defined in `rope.c'. - Function: SCM long2num (long N) - Function: SCM ulong2num (unsigned long N) Return an object of type `SCM' corresponding to the `long' or `unsigned long' argument N. If N cannot be converted, `BOOL_F' is returned. Which numbers can be converted depends on whether SCM was compiled with the `BIGDIG' or `FLOATS' flags. To convert integer numbers of smaller types (`short' or `char'), use the macro `MAKINUM(n)'. - Function: long num2long (SCM NUM, char *POS, char *S_CALLER) - Function: unsigned long num2ulong (SCM NUM, char *POS, char *S_CALLER) - Function: unsigned short num2ushort (SCM NUM, char *POS, char *S_CALLER) - Function: unsigned char num2uchar (SCM NUM, char *POS, char *S_CALLER) These functions are used to check and convert `SCM' arguments to the named C type. The first argument NUM is checked to see it it is within the range of the destination type. If so, the converted number is returned. If not, the `ASSERT' macro calls `wta' with NUM and strings POS and S_CALLER. For a listing of useful predefined POS macros, *Note C Macros::. _Note:_ Inexact numbers are accepted only by `num2long' and `num2ulong' (for when `SCM' is compiled without bignums). To convert inexact numbers to exact numbers, *Note inexact->exact: (r5rs)Numerical operations. - Function: unsigned long scm_addr (SCM ARGS, char *S_NAME) Returns a pointer (cast to an `unsigned long') to the storage corresponding to the location accessed by `aref(CAR(args),CDR(args))'. The string S_NAME is used in any messages from error calls by `scm_addr'. `scm_addr' is useful for performing C operations on strings or other uniform arrays (*note Uniform Array::). _Note:_ While you use a pointer returned from `scm_addr' you must keep a pointer to the associated `SCM' object in a stack allocated variable or GC-protected location in order to assure that SCM does not reuse that storage before you are done with it. - Function: SCM makfrom0str (char *SRC) - Function: SCM makfromstr (char *SRC, sizet LEN) Return a newly allocated string `SCM' object copy of the null-terminated string SRC or the string SRC of length LEN, respectively. - Function: SCM makfromstrs (int ARGC, char **ARGV) Returns a newly allocated `SCM' list of strings corresponding to the ARGC length array of null-terminated strings ARGV. If ARGV is less than `0', ARGV is assumed to be `NULL' terminated. `makfromstrs' is used by `scm_init_from_argv' to convert the arguments SCM was called with to a `SCM' list which is the value of SCM procedure calls to `program-arguments' (*note program-arguments: SCM Session.). - Function: char ** makargvfrmstrs (SCM ARGS, char *S_NAME) Returns a `NULL' terminated list of null-terminated strings copied from the `SCM' list of strings ARGS. The string S_NAME is used in messages from error calls by `makargvfrmstrs'. `makargvfrmstrs' is useful for constructing argument lists suitable for passing to `main' functions. - Function: void must_free_argv (char **ARGV) Frees the storage allocated to create ARGV by a call to `makargvfrmstrs'.  File: scm.info, Node: Continuations, Next: Evaluation, Prev: Type Conversions, Up: Operations Continuations ------------- The source files `continue.h' and `continue.c' are designed to function as an independent resource for programs wishing to use continuations, but without all the rest of the SCM machinery. The concept of continuations is explained in *Note call-with-current-continuation: (r5rs)Control features. The C constructs `jmp_buf', `setjmp', and `longjmp' implement escape continuations. On VAX and Cray platforms, the setjmp provided does not save all the registers. The source files `setjump.mar', `setjump.s', and `ugsetjump.s' provide implementations which do meet this criteria. SCM uses the names `jump_buf', `setjump', and `longjump' in lieu of `jmp_buf', `setjmp', and `longjmp' to prevent name and declaration conflicts. - Data type: CONTINUATION jmpbuf length stkbse other parent is a `typedef'ed structure holding all the information needed to represent a continuation. The OTHER slot can be used to hold any data the user wishes to put there by defining the macro `CONTINUATION_OTHER'. - Macro: SHORT_ALIGN If `SHORT_ALIGN' is `#define'd (in `scmfig.h'), then the it is assumed that pointers in the stack can be aligned on `short int' boundaries. - Data type: STACKITEM is a pointer to objects of the size specified by `SHORT_ALIGN' being `#define'd or not. - Macro: CHEAP_CONTINUATIONS If `CHEAP_CONTINUATIONS' is `#define'd (in `scmfig.h') each `CONTINUATION' has size `sizeof CONTINUATION'. Otherwise, all but "root" `CONTINUATION's have additional storage (immediately following) to contain a copy of part of the stack. _Note:_ On systems with nonlinear stack disciplines (multiple stacks or non-contiguous stack frames) copying the stack will not work properly. These systems need to #define `CHEAP_CONTINUATIONS' in `scmfig.h'. - Macro: STACK_GROWS_UP Expresses which way the stack grows by its being `#define'd or not. - Variable: long thrown_value Gets set to the VALUE passed to `throw_to_continuation'. - Function: long stack_size (STACKITEM *START) Returns the number of units of size `STACKITEM' which fit between START and the current top of stack. No check is done in this routine to ensure that START is actually in the current stack segment. - Function: CONTINUATION * make_root_continuation (STACKITEM *STACK_BASE) Allocates (`malloc') storage for a `CONTINUATION' of the current extent of stack. This newly allocated `CONTINUATION' is returned if successful, `0' if not. After `make_root_continuation' returns, the calling routine still needs to `setjump(NEW_CONTINUATION->jmpbuf)' in order to complete the capture of this continuation. - Function: CONTINUATION * make_continuation (CONTINUATION *PARENT_CONT) Allocates storage for the current `CONTINUATION', copying (or encapsulating) the stack state from `PARENT_CONT->stkbse' to the current top of stack. The newly allocated `CONTINUATION' is returned if successful, `0'q if not. After `make_continuation' returns, the calling routine still needs to `setjump(NEW_CONTINUATION->jmpbuf)' in order to complete the capture of this continuation. - Function: void free_continuation (CONTINUATION *CONT) Frees the storage pointed to by CONT. Remember to free storage pointed to by `CONT->other'. - Function: void throw_to_continuation (CONTINUATION *CONT, long VALUE, CONTINUATION *ROOT_CONT) Sets `thrown_value' to VALUE and returns from the continuation CONT. If `CHEAP_CONTINUATIONS' is `#define'd, then `throw_to_continuation' does `longjump(CONT->jmpbuf, val)'. If `CHEAP_CONTINUATIONS' is not `#define'd, the CONTINUATION CONT contains a copy of a portion of the C stack (whose bound must be `CONT(ROOT_CONT)->stkbse'). Then: * the stack is grown larger than the saved stack, if neccessary. * the saved stack is copied back into it's original position. * `longjump(CONT->jmpbuf, val)';  File: scm.info, Node: Evaluation, Prev: Continuations, Up: Operations Evaluation ---------- SCM uses its type representations to speed evaluation. All of the `subr' types (*note Subr Cells::) are `tc7' types. Since the `tc7' field is in the low order bit position of the `CAR' it can be retrieved and dispatched on quickly by dereferencing the SCM pointer pointing to it and masking the result. All the SCM "Special Forms" get translated to immediate symbols (`isym') the first time they are encountered by the interpreter (`ceval'). The representation of these immediate symbols is engineered to occupy the same bits as `tc7'. All the `isym's occur only in the `CAR' of lists. If the `CAR' of a expression to evaluate is not immediate, then it may be a symbol. If so, the first time it is encountered it will be converted to an immediate type `ILOC' or `GLOC' (*note Immediates::). The codes for `ILOC' and `GLOC' lower 7 bits distinguish them from all the other types we have discussed. Once it has determined that the expression to evaluate is not immediate, `ceval' need only retrieve and dispatch on the low order 7 bits of the `CAR' of that cell, regardless of whether that cell is a closure, header, or subr, or a cons containing `ILOC' or `GLOC'. In order to be able to convert a SCM symbol pointer to an immediate `ILOC' or `GLOC', the evaluator must be holding the pointer to the list in which that symbol pointer occurs. Turning this requirement to an advantage, `ceval' does not recursively call itself to evaluate symbols in lists; It instead calls the macro "EVALCAR". `EVALCAR' does symbol lookup and memoization for symbols, retrieval of values for `ILOC's and `GLOC's, returns other immediates, and otherwise recursively calls itself with the `CAR' of the list. `ceval' inlines evaluation (using `EVALCAR') of almost all procedure call arguments. When `ceval' needs to evaluate a list of more than length 3, the procedure `eval_args' is called. So `ceval' can be said to have one level lookahead. The avoidance of recursive invocations of `ceval' for the most common cases (special forms and procedure calls) results in faster execution. The speed of the interpreter is currently limited on most machines by interpreter size, probably having to do with its cache footprint. In order to keep the size down, certain `EVALCAR' calls which don't need to be fast (because they rarely occur or because they are part of expensive operations) are instead calls to the C function `evalcar'. - Variable: symhash Top level symbol values are stored in the `symhash' table. `symhash' is an array of lists of `ISYM's and pairs of symbols and values. - Immediate: ILOC Whenever a symbol's value is found in the local environment the pointer to the symbol in the code is replaced with an immediate object (`ILOC') which specifies how many environment frames down and how far in to go for the value. When this immediate object is subsequently encountered, the value can be retrieved quickly. `ILOC's work up to a maximum depth of 4096 frames or 4096 identifiers in a frame. Radey Shouman added "FARLOC" to handle cases exceeding these limits. A `FARLOC' consists of a pair whose CAR is the immediate type `IM_FARLOC_CAR' or `IM_FARLOC_CDR', and whose CDR is a pair of INUMs specifying the frame and distance with a larger range than `ILOC's span. Adding `#define TEST_FARLOC' to `eval.c' causes `FARLOC's to be generated for all local identifiers; this is useful only for testing memoization. - Immediate: GLOC Pointers to symbols not defined in local environments are changed to one plus the value cell address in symhash. This incremented pointer is called a `GLOC'. The low order bit is normally reserved for GCmark; But, since references to variables in the code always occur in the `CAR' position and the GCmark is in the `CDR', there is no conflict. If the compile FLAG `CAUTIOUS' is #defined then the number of arguments is always checked for application of closures. If the compile FLAG `RECKLESS' is #defined then they are not checked. Otherwise, number of argument checks for closures are made only when the function position (whose value is the closure) of a combination is not an `ILOC' or `GLOC'. When the function position of a combination is a symbol it will be checked only the first time it is evaluated because it will then be replaced with an `ILOC' or `GLOC'. - Macro: EVAL expression env - Macro: SIDEVAL expression env `EVAL' Returns the result of evaluating EXPRESSION in ENV. `SIDEVAL' evaluates EXPRESSION in ENV when the value of the expression is not used. Both of these macros alter the list structure of EXPRESSION as it is memoized and hence should be used only when it is known that EXPRESSION will not be referenced again. The C function `eval' is safe from this problem. - Function: SCM eval (SCM EXPRESSION) Returns the result of evaluating EXPRESSION in the top-level environment. `eval' copies `expression' so that memoization does not modify `expression'.  File: scm.info, Node: Program Self-Knowledge, Next: Improvements To Make, Prev: Operations, Up: The Implementation Program Self-Knowledge ====================== * Menu: * File-System Habitat:: * Executable Pathname:: * Script Support::  File: scm.info, Node: File-System Habitat, Next: Executable Pathname, Prev: Program Self-Knowledge, Up: Program Self-Knowledge File-System Habitat ------------------- Where should software reside? Although individually a minor annoyance, cumulatively this question represents many thousands of frustrated user hours spent trying to find support files or guessing where packages need to be installed. Even simple programs require proper habitat; games need to find their score files. Aren't there standards for this? Some Operating Systems have devised regimes of software habitats - only to have them violated by large software packages and imports from other OS varieties. In some programs, the expected locations of support files are fixed at time of compilation. This means that the program may not run on configurations unanticipated by the authors. Compiling locations into a program also can make it immovable - necessitating recompilation to install it. Programs of the world unite! You have nothing to lose but loss itself. The function `find_impl_file' in `scm.c' is an attempt to create a utility (for inclusion in programs) which will hide the details of platform-dependent file habitat conventions. It takes as input the pathname of the executable file which is running. If there are systems for which this information is either not available or unrelated to the locations of support files, then a higher level interface will be needed. - Function: char * find_impl_file (char *EXEC_PATH, char *GENERIC_NAME, char *INITNAME, char *SEP) Given the pathname of this executable (EXEC_PATH), test for the existence of INITNAME in the implementation-vicinity of this program. Return a newly allocated string of the path if successful, 0 if not. The SEP argument is a _null-terminated string_ of the character used to separate directory components. * One convention is to install the support files for an executable program in the same directory as the program. This possibility is tried first, which satisfies not only programs using this convention, but also uninstalled builds when testing new releases, etc. * Another convention is to install the executables in a directory named `bin', `BIN', `exe', or `EXE' and support files in a directroy named `lib', which is a peer the executable directory. This arrangement allows multiple executables can be stored in a single directory. For example, the executable might be in `/usr/local/bin/' and initialization file in `/usr/local/lib/'. If the executable directory name matches, the peer directroy `lib' is tested for INITNAME. * Sometimes `lib' directories become too crowded. So we look in any subdirectories of `lib' or `src' having the name (sans type suffix such as `.EXE') of the program we are running. For example, the executable might be `/usr/local/bin/foo' and initialization file in `/usr/local/lib/foo/'. * But the executable name may not be the usual program name; So also look in any GENERIC_NAME subdirectories of `lib' or `src' peers. * Finally, if the name of the executable file being run has a (system dependent) suffix which is not needed to invoke the program, then look in a subdirectory (of the one containing the executable file) named for the executable (without the suffix); And look in a GENERIC_NAME subdirectory. For example, the executable might be `C:\foo\bar.exe' and the initialization file in `C:\foo\bar\'.  File: scm.info, Node: Executable Pathname, Next: Script Support, Prev: File-System Habitat, Up: Program Self-Knowledge Executable Pathname ------------------- For purposes of finding `Init5d6.scm', dumping an executable, and dynamic linking, a SCM session needs the pathname of its executable image. When a program is executed by MS-DOS, the full pathname of that executable is available in `argv[0]'. This value can be passed directly to `find_impl_file' (*note File-System Habitat::). In order to find the habitat for a unix program, we first need to know the full pathname for the associated executable file. - Function: char * dld_find_executable (const char *COMMAND) `dld_find_executable' returns the absolute path name of the file that would be executed if COMMAND were given as a command. It looks up the environment variable PATH, searches in each of the directory listed for COMMAND, and returns the absolute path name for the first occurrence. Thus, it is advisable to invoke `dld_init' as: main (int argc, char **argv) { ... if (dld_init (dld_find_executable (argv[0]))) { ... } ... } *Note:* If the current process is executed using the `execve' call without passing the correct path name as argument 0, `dld_find_executable (argv[0]) ' will also fail to locate the executable file. `dld_find_executable' returns zero if `command' is not found in any of the directories listed in `PATH'.  File: scm.info, Node: Script Support, Prev: Executable Pathname, Up: Program Self-Knowledge Script Support -------------- Source code for these C functions is in the file `script.c'. *Note Scripting:: for a description of script argument processing. `script_find_executable' is only defined on unix systems. - Function: char * script_find_executable (const char *NAME) `script_find_executable' returns the path name of the executable which is invoked by the script file NAME; NAME if it is a binary executable (not a script); or 0 if NAME does not exist or is not executable. - Function: char ** script_process_argv (int ARGC; char **ARGV) Given an "main" style argument vector ARGV and the number of arguments, ARGC, `script_process_argv' returns a newly allocated argument vector in which the second line of the script being invoked is substituted for the corresponding meta-argument. If the script does not have a meta-argument, or if the file named by the argument following a meta-argument cannot be opened for reading, then 0 is returned. `script_process_argv' correctly processes argument vectors of nested script invocations. - Function: int script_count_argv (char **ARGV) Returns the number of argument strings in ARGV.  File: scm.info, Node: Improvements To Make, Prev: Program Self-Knowledge, Up: The Implementation Improvements To Make ==================== * Allow users to set limits for `malloc()' storage. * Prefix and make more uniform all C function, variable, and constant names. Provide a file full of #define's to provide backward compatability. * `lgcd()' _needs_ to generate at most one bignum, but currently generates more. * `divide()' could use shifts instead of multiply and divide when scaling. * Currently, `dump'ing an executable does not preserve ports. When loading a `dump'ed executable, disk files could be reopened to the same file and position as they had when the executable was dumped. * Copying all of the stack is wasteful of storage. Any time a call-with-current-continuation is called the stack could be re-rooted with a frame which calls the contin just created. This in combination with checking stack depth could also be used to allow stacks deeper than 64K on the IBM PC. * In the quest for speed, there has been some discussion about a "Forth" style Scheme interpreter. Provided there is still type code space available in SCM, if we devote some of the IMCAR codes to "inlined" operations, we should get a significant performance boost. What is eliminated is the having to look up a `GLOC' or `ILOC' and then dispatch on the subr type. The IMCAR operation would be dispatched to directly. Another way to view this is that we make available special form versions of `CAR', `CDR', etc. Since the actual operation code is localized in the interpreter, it is much easier than uncompilation and then recompilation to handle `(trace car)'; For instance a switch gets set which tells the interpreter to instead always look up the values of the associated symbols. * Menu: * Finishing Dynamic Linking::  File: scm.info, Node: Finishing Dynamic Linking, Prev: Improvements To Make, Up: Improvements To Make Finishing Dynamic Linking ------------------------- Scott Schwartz suggests: One way to tidy up the dynamic loading stuff would be to grab the code from perl5. VMS ... George Carrette (gjc@mitech.com) outlines how to dynamically link on VMS. There is already some code in `dynl.c' to do this, but someone with a VMS system needs to finish and debug it. 1. Say you have this `main.c' program: main() {init_lisp(); lisp_repl();} 2. and you have your lisp in files `repl.c', `gc.c', `eval.c' and there are some toplevel non-static variables in use called `the_heap', `the_environment', and some read-only toplevel structures, such as `the_subr_table'. $ LINK/SHARE=LISPRTL.EXE/DEBUG REPL.OBJ,GC.OBJ,EVAL.OBJ,LISPRTL.OPT/OPT 3. where `LISPRTL.OPT' must contain at least this: SYS$LIBRARY:VAXCRTL/SHARE UNIVERSAL=init_lisp UNIVERSAL=lisp_repl PSECT_ATTR=the_subr_table,SHR,NOWRT,LCL PSECT_ATTR=the_heap,NOSHR,LCL PSECT_ATTR=the_environment,NOSHR,LCL _Notice:_ The "psect" (Program Section) attributes. `LCL' means to keep the name local to the shared library. You almost always want to do that for a good clean library. `SHR,NOWRT' means shared-read-only. Which is the default for code, and is also good for efficiency of some data structures. `NOSHR,LCL' is what you want for everything else. Note: If you do not have a handy list of all these toplevel variables, do not dispair. Just do your link with the /MAP=LISPRTL.MAP/FULL and then search the map file, $SEARCH/OUT=LISPRTL.LOSERS LISPRTL.MAP ", SHR,NOEXE, RD, WRT" And use an emacs keyboard macro to muck the result into the proper form. Of course only the programmer can tell if things can be made read-only. I have a DCL command procedure to do this if you want it. 4. Now MAIN.EXE would be linked thusly: $ DEFINE LISPRTL USER$DISK:[JAFFER]LISPRTL.EXE $LINK MAIN.OBJ,SYS$INPUT:/OPT SYS$LIBRARY:VAXCRTL/SHARE LISPRTL/SHARE Note the definition of the `LISPRTL' logical name. Without such a definition you will need to copy `LISPRTL.EXE' over to `SYS$SHARE:' (aka `SYS$LIBRARY:') in order to invoke the main program once it is linked. 5. Now say you have a file of optional subrs, `MYSUBRS.C'. And there is a routine `INIT_MYSUBRS' that must be called before using it. $ CC MYSUBRS.C $ LINK/SHARE=MYSUBRS.EXE MYSUBRS.OBJ,SYS$INPUT:/OPT SYS$LIBRARY:VAXCRTL/SHARE LISPRTL/SHARE UNIVERSAL=INIT_MYSUBRS Ok. Another hint is that you can avoid having to add the `PSECT' declaration of `NOSHR,LCL' by declaring variables `status' in the C language source. That works great for most things. 6. Then the dynamic loader would have to do this: {void (*init_fcn)(); long retval; retval = lib$find_image_symbol("MYSUBRS","INIT_MYSUBRS",&init_fcn, "SYS$DISK:[].EXE"); if (retval != SS$_NORMAL) error(...); (*init_fcn)();} But of course all string arguments must be `(struct dsc$descriptor *)' and the last argument is optional if `MYSUBRS' is defined as a logical name or if `MYSUBRS.EXE' has been copied over to `SYS$SHARE'. The other consideration is that you will want to turn off or other interrupt handling while you are inside most `lib$' calls. As far as the generation of all the `UNIVERSAL=...' declarations. Well, you could do well to have that automatically generated from the public `LISPRTL.H' file, of course. VMS has a good manual called the `Guide to Writing Modular Procedures' or something like that, which covers this whole area rather well, and also talks about advanced techniques, such as a way to declare a program section with a pointer to a procedure that will be automatically invoked whenever any shared image is dynamically activated. Also, how to set up a handler for normal or abnormal program exit so that you can clean up side effects (such as opening a database). But for use with `LISPRTL' you probably don't need that hair. One fancier option that is useful under VMS for `LISPLIB.EXE' is to define all your exported procedures through an "call vector" instead of having them just be pointers into random places in the image, which is what you get by using `UNIVERSAL'. If you set up the call vector thing correctly it will allow you to modify and relink `LISPLIB.EXE' without having to relink programs that have been linked against it. Windows NT .......... George Carrette (gjc@mitech.com) outlines how to dynamically link on Windows NT: * The Software Developers Kit has a sample called SIMPLDLL. Here is the gist of it, following along the lines of the VMS description above (contents of a makefile for the SDK NMAKE) LISPLIB.exp: LISPLIB.lib: LISPLIB.def $(implib) -machine:$(CPU) -def:LISPLIB.def -out:LISPLIB.lib LISPLIB.DLL : $(LISPLIB_OBJS) LISPLIB.EXP $(link) $(linkdebug) \ -dll \ -out:LISPLIB.DLL \ LISPLIB.EXP $(LISPLIB_OBJS) $(conlibsdll) * The `LISPDEF.DEF' file has this: LIBRARY lisplib EXPORT init_lisp init_repl * And `MAIN.EXE' using: CLINK = $(link) $(ldebug) $(conflags) -out:$*.exe $** $(conlibsdll) MAIN.EXE : MAIN.OBJ LISPLIB.LIB $(CLINK) * And `MYSUBRS.DLL' is produced using: mysubrs.exp: mysubrs.lib: mysubrs.def $(implib) -machine:$(CPU) -def:MYSUBRS.def -out:MYSUBRS.lib mysubrs.dll : mysubrs.obj mysubrs.exp mysubrs.lib $(link) $(linkdebug) \ -dll \ -out:mysubrs.dll \ MYSUBRS.OBJ MYSUBRS.EXP LISPLIB.LIB $(conlibsdll) * Where `MYSUBRS.DEF' has LIBRARY mysubrs EXPORT INIT_MYSUBRS * And the dynamic loader looks something like this, calling the two procedures `LoadLibrary' and `GetProcAddress'. LISP share_image_load(LISP fname) {long iflag; LISP retval,(*fcn)(void); HANDLE hLib; DWORD err; char *libname,fcnname[64]; iflag = nointerrupt(1); libname = c_string(fname); _snprintf(fcnname,sizeof(fcnname),"INIT_%s",libname); if (!(hLib = LoadLibrary(libname))) {err = GetLastError(); retval = list2(fname,LSPNUM(err)); serror1("library failed to load",retval);} if (!(fcn = (LISP (*)(void)) GetProcAddress(hLib,fcnname))) {err = GetLastError(); retval = list2(fname,LSPNUM(err)); serror1("could not find library init procedure",retval);} retval = (*fcn)(); nointerrupt(iflag); return(retval);} * _Note:_ in VMS the linker and dynamic loader is case sensitive, but all the language compilers, including C, will by default upper-case external symbols for use by the linker, although the debugger gets its own symbols and case sensitivity is language mode dependant. In Windows NT things are case sensitive generally except for file and device names, which are case canonicalizing like in the Symbolics filesystem. * _Also:_ All this WINDOWS NT stuff will work in MS-DOS MS-Windows 3.1 too, by a method of compiling and linking under Windows NT, and then copying various files over to MS-DOS/WINDOWS.  File: scm.info, Node: Index, Prev: The Implementation, Up: Top Procedure and Macro Index ************************* This is an alphabetical list of all the procedures and macros in SCM. * Menu: * #!: Unix Scheme Scripts. * #': Syntax Extensions. * #+: Syntax Extensions. * #-: Syntax Extensions. * #.: Syntax Extensions. * #;text-till-end-of-line: Syntax Extensions. * #\token: Syntax Extensions. * #|: Syntax Extensions. * $abs: Numeric. * $acos: Numeric. * $acosh: Numeric. * $asin: Numeric. * $asinh: Numeric. * $atan: Numeric. * $atan2: Numeric. * $atanh: Numeric. * $cos: Numeric. * $cosh: Numeric. * $exp: Numeric. * $expt: Numeric. * $log: Numeric. * $log10: Numeric. * $sin: Numeric. * $sinh: Numeric. * $sqrt: Numeric. * $tan: Numeric. * $tanh: Numeric. * -: SCM Options. * ---: SCM Options. * ---c-source-files=: Build Options. * ---compiler-options=: Build Options. * ---defines=: Build Options. * ---features=: Build Options. * ---help: SCM Options. * ---initialization=: Build Options. * ---libraries=: Build Options. * ---linker-options=: Build Options. * ---no-init-file: SCM Options. * ---object-files=: Build Options. * ---outname=: Build Options. * ---platform=: Build Options. * ---scheme-initial=: Build Options. * ---type=: Build Options. * ---version: SCM Options. * --batch-dialect=: Build Options. * --script-name=: Build Options. * -a: SCM Options. * -b: SCM Options. * -c <1>: SCM Options. * -c: Build Options. * -d: SCM Options. * -D: Build Options. * -e: SCM Options. * -f: SCM Options. * -F: Build Options. * -h <1>: SCM Options. * -h: Build Options. * -i <1>: SCM Options. * -i: Build Options. * -j: Build Options. * -l <1>: SCM Options. * -l: Build Options. * -m: SCM Options. * -no-init-file: SCM Options. * -o <1>: SCM Options. * -o: Build Options. * -p <1>: SCM Options. * -p: Build Options. * -q: SCM Options. * -r: SCM Options. * -s <1>: SCM Options. * -s: Build Options. * -t: Build Options. * -u: SCM Options. * -v: SCM Options. * -w: Build Options. * @apply: Low Level Syntactic Hooks. * @copy-tree: Miscellaneous Procedures. * @macroexpand1: Syntactic Hooks for Hygienic Macros. * _exclusive: Files and Ports. * _ionbf: Files and Ports. * _tracked: Files and Ports. * abort: Internal State. * access: I/O-Extensions. * acct: Unix Extensions. * acons: Miscellaneous Procedures. * acosh: Numeric. * add-alias: Configure Module Catalog. * add-finalizer: Interrupts. * add-link: Configure Module Catalog. * add-source: Configure Module Catalog. * alarm: Interrupts. * alarm-interrupt: Interrupts. * ALLOW_INTS: Signals. * alrm_signal: Signals. * ARGC: Cells. * arithmetic-error: Interrupts. * array->list: Conventional Arrays. * array-contents: Conventional Arrays. * array-copy!: Conventional Arrays. * array-dimensions: Conventional Arrays. * array-equal?: Conventional Arrays. * array-fill!: Conventional Arrays. * array-for-each: Array Mapping. * array-in-bounds?: Conventional Arrays. * array-index-map!: Array Mapping. * array-map!: Array Mapping. * array-prototype: Uniform Array. * array-rank: Conventional Arrays. * array-ref: Conventional Arrays. * array-set!: Conventional Arrays. * array-shape: Conventional Arrays. * array? <1>: Uniform Array. * array?: Conventional Arrays. * asinh: Numeric. * ASRTGO: C Macros. * ASSERT: C Macros. * atanh: Numeric. * bit-count: Bit Vectors. * bit-count*: Bit Vectors. * bit-invert!: Bit Vectors. * bit-position: Bit Vectors. * bit-set*!: Bit Vectors. * boot-tail <1>: Dump. * boot-tail: SCM Session. * box: Curses Miscellany. * broken-pipe: Posix Extensions. * call-with-outputs: Files and Ports. * CAR: Cells. * cbreak: Terminal Mode Setting. * CCLO_LENGTH: Header Cells. * CDR: Cells. * char: Type Conversions. * char-ready: Files and Ports. * char-ready? <1>: Socket. * char-ready?: Files and Ports. * CHARS: Header Cells. * chdir: I/O-Extensions. * CHEAP_CONTINUATIONS: Continuations. * chmod: I/O-Extensions. * chown: Posix Extensions. * clearok: Output Options Setting. * close-port <1>: Window Manipulation. * close-port <2>: Posix Extensions. * close-port: Files and Ports. * closedir: I/O-Extensions. * CLOSEDP: Ptob Cells. * CLOSUREP: Cells. * CODE: Cells. * comment: Syntax Extensions. * CONSP: Cells. * copy-tree: Miscellaneous Procedures. * cosh: Numeric. * could-not-open: Interrupts. * current-error-port: Files and Ports. * current-input-port: Files and Ports. * current-time: Time. * default-input-port: Line Editing. * default-output-port: Line Editing. * defconst: Syntax Extensions. * DEFER_INTS: Signals. * defined?: Syntax Extensions. * defmacro: Syntax Extensions. * defsyntax: Low Level Syntactic Hooks. * defvar: Syntax Extensions. * dimensions->uniform-array: Uniform Array. * directory-for-each: I/O-Extensions. * display: Output. * dld_find_executable: Executable Pathname. * dump: Dump. * duplicate-port: I/O-Extensions. * dyn:call: Dynamic Linking. * dyn:link: Dynamic Linking. * dyn:main-call: Dynamic Linking. * dyn:unlink: Dynamic Linking. * echo: Terminal Mode Setting. * ed: Editing Scheme Code. * enclose-array: Conventional Arrays. * end-of-program: Interrupts. * endwin: Curses. * ENV: Cells. * errno: Errors. * error: Errors. * eval: Evaluation. * EVAL: Evaluation. * eval: Miscellaneous Procedures. * eval-string: Miscellaneous Procedures. * exec-self: Internal State. * execl: I/O-Extensions. * execlp: I/O-Extensions. * execpath: Internal State. * execv: I/O-Extensions. * execvp: I/O-Extensions. * exit: SCM Session. * extended-environment: Syntactic Hooks for Hygienic Macros. * file-position: I/O-Extensions. * file-set-position: I/O-Extensions. * fileno: I/O-Extensions. * final_scm: Embedding SCM. * find_impl_file: File-System Habitat. * force-output: Window Manipulation. * fork: Posix Extensions. * FPORTP: Ptob Cells. * free_continuation: Continuations. * freshline: Files and Ports. * gc: Internal State. * gc-hook: Interrupts. * gc_mark: Marking Cells. * GCCDR: Marking Cells. * GCTYP16: Marking Cells. * gentemp: Syntax Extensions. * get-internal-real-time: Time. * get-internal-run-time: Time. * getcwd: I/O-Extensions. * getegid: Posix Extensions. * geteuid: Posix Extensions. * getgid: Posix Extensions. * getgr: Posix Extensions. * getgroups: Posix Extensions. * gethost: Host Data. * getlogin: Posix Extensions. * getnet: Host Data. * getpeername: Internet Addresses and Socket Names. * getpid: I/O-Extensions. * getppid: Posix Extensions. * getproto: Host Data. * getpw: Posix Extensions. * getserv: Host Data. * getsockname: Internet Addresses and Socket Names. * getuid: Posix Extensions. * getyx: Input. * hang-up: Interrupts. * ICHR: Immediates. * ICHRP: Immediates. * identifier->symbol: Syntactic Hooks for Hygienic Macros. * identifier-equal?: Syntactic Hooks for Hygienic Macros. * identifier?: Syntactic Hooks for Hygienic Macros. * idlok: Output Options Setting. * IFLAGP: Immediates. * IMP: Immediates. * inet:address->string: Internet Addresses and Socket Names. * inet:local-network-address: Internet Addresses and Socket Names. * inet:make-address: Internet Addresses and Socket Names. * inet:network: Internet Addresses and Socket Names. * inet:string->address: Internet Addresses and Socket Names. * init_buf0: Embedding SCM. * init_sbrk: Embedding SCM. * init_signals <1>: Embedding SCM. * init_signals: Signals. * initscr: Curses. * INPORTP: Ptob Cells. * int_signal: Signals. * integer->line-number: Line Numbers. * INUM: Immediates. * INUMP: Immediates. * isatty?: Files and Ports. * ISYMCHARS: Immediates. * ISYMNUM: Immediates. * ISYMP: Immediates. * kill: Posix Extensions. * leaveok: Output Options Setting. * LENGTH: Header Cells. * line-editing: Line Editing. * line-number: Miscellaneous Procedures. * line-number->integer: Line Numbers. * line-number?: Line Numbers. * link: Posix Extensions. * list->uniform-array: Uniform Array. * list-file: Miscellaneous Procedures. * load: Dynamic Linking. * load-string: Miscellaneous Procedures. * logaref: Uniform Array. * logaset!: Uniform Array. * long: Type Conversions. * long2num: Type Conversions. * lstat: Unix Extensions. * macroexpand: Syntax Extensions. * macroexpand-1: Syntax Extensions. * main: Embedding SCM. * makargvfrmstrs: Type Conversions. * makcclo: Header Cells. * make-arbiter: Process Synchronization. * make-array: Conventional Arrays. * make-edited-line-port: Line Editing. * make-exchanger: Process Synchronization. * make-shared-array: Conventional Arrays. * make-soft-port: Soft Ports. * make-stream-socket: Socket. * make-stream-socketpair: Socket. * make_continuation: Continuations. * make_gsubr: Defining Subrs. * make_root_continuation: Continuations. * makfrom0str: Type Conversions. * makfromstr: Type Conversions. * makfromstrs: Type Conversions. * MAKICHR: Immediates. * MAKIFLAG: Immediates. * MAKINUM: Immediates. * MAKISYM: Immediates. * MAKSPCSYM: Immediates. * mark_locations: Marking Cells. * milli-alarm: Interrupts. * mkdir: I/O-Extensions. * mknod: Unix Extensions. * must_free: Allocating memory. * must_free_argv: Type Conversions. * must_malloc: Allocating memory. * must_malloc_cell: Allocating memory. * must_realloc: Allocating memory. * must_realloc_cell: Allocating memory. * mvwin: Window Manipulation. * NCONSP: Cells. * NEWCELL: Cells. * newwin: Window Manipulation. * nice: Unix Extensions. * NIMP: Immediates. * NINUMP: Immediates. * nl: Terminal Mode Setting. * nocbreak: Terminal Mode Setting. * nodelay: Output Options Setting. * noecho: Terminal Mode Setting. * nonl: Terminal Mode Setting. * noraw: Terminal Mode Setting. * NSTRINGP: Header Cells. * num2long: Type Conversions. * NVECTORP: Header Cells. * open-file: Files and Ports. * open-input-pipe: Posix Extensions. * open-output-pipe: Posix Extensions. * open-pipe: Posix Extensions. * open-ports: Files and Ports. * opendir: I/O-Extensions. * OPENP: Ptob Cells. * OPFPORTP: Ptob Cells. * OPINFPORTP: Ptob Cells. * OPINPORTP: Ptob Cells. * OPOUTFPORTP: Ptob Cells. * OPOUTPORTP: Ptob Cells. * OPPORTP: Ptob Cells. * out-of-storage: Interrupts. * OUTPORTP: Ptob Cells. * overlay: Window Manipulation. * overwrite: Window Manipulation. * perror: Errors. * pi*: Numeric. * pi/: Numeric. * pipe: Posix Extensions. * port-closed?: Files and Ports. * port-column: Miscellaneous Procedures. * port-filename: Miscellaneous Procedures. * port-line: Miscellaneous Procedures. * port-type: Files and Ports. * PORTP: Ptob Cells. * print <1>: Miscellaneous Procedures. * print: Debugging Scheme Code. * print-args: Debugging Scheme Code. * procedure->identifier-macro: Low Level Syntactic Hooks. * procedure->macro: Low Level Syntactic Hooks. * procedure->memoizing-macro: Low Level Syntactic Hooks. * procedure->syntax: Low Level Syntactic Hooks. * procedure-documentation: Syntax Extensions. * profile-alarm: Interrupts. * profile-alarm-interrupt: Interrupts. * program-arguments: SCM Session. * putenv: I/O-Extensions. * qase: Syntax Extensions. * quit: SCM Session. * raw: Terminal Mode Setting. * read-char <1>: Input. * read-char: Files and Ports. * read-numbered: Line Numbers. * read:sharp: Low Level Syntactic Hooks. * read:sharp-char: Low Level Syntactic Hooks. * readdir: I/O-Extensions. * readlink: Unix Extensions. * record-printer-set!: Records. * redirect-port!: I/O-Extensions. * refresh: Window Manipulation. * regcomp: Regular Expression Pattern Matching. * regerror: Regular Expression Pattern Matching. * regexec: Regular Expression Pattern Matching. * regmatch: Regular Expression Pattern Matching. * regmatch?: Regular Expression Pattern Matching. * regmatchv: Regular Expression Pattern Matching. * regsearch: Regular Expression Pattern Matching. * regsearchv: Regular Expression Pattern Matching. * release-arbiter: Process Synchronization. * rename-file: I/O-Extensions. * renamed-identifier: Syntactic Hooks for Hygienic Macros. * renaming-transformer: Syntactic Hooks for Hygienic Macros. * reopen-file: I/O-Extensions. * require: Dynamic Linking. * resetty: Terminal Mode Setting. * restart: Internal State. * restore_signals: Embedding SCM. * rewinddir: I/O-Extensions. * rmdir: I/O-Extensions. * room: Internal State. * savetty: Terminal Mode Setting. * scalar->array: Array Mapping. * scm_evstr: Callbacks. * scm_find_execpath: Embedding SCM. * scm_find_implpath: Embedding SCM. * scm_init_from_argv: Embedding SCM. * scm_ldfile: Callbacks. * scm_ldprog: Callbacks. * scm_ldstr: Callbacks. * scm_top_level: Embedding SCM. * script_count_argv: Script Support. * script_find_executable: Script Support. * script_process_argv: Script Support. * scroll: Output. * scrollok: Output Options Setting. * serial-array-copy!: Conventional Arrays. * serial-array-map!: Array Mapping. * set!: Syntax Extensions. * setegid: Posix Extensions. * seteuid: Posix Extensions. * setgid: Posix Extensions. * setgrent: Posix Extensions. * sethostent: Host Data. * setnetent: Host Data. * setprotoent: Host Data. * setpwent: Posix Extensions. * setservent: Host Data. * setuid: Posix Extensions. * short: Type Conversions. * SHORT_ALIGN: Continuations. * SIDEVAL: Evaluation. * sinh: Numeric. * socket-name:address: Internet Addresses and Socket Names. * socket-name:family: Internet Addresses and Socket Names. * socket-name:port-number: Internet Addresses and Socket Names. * socket:accept: Socket. * socket:bind: Socket. * socket:connect: Socket. * socket:listen: Socket. * socket:shutdown: Socket. * stack-trace: Errors. * STACK_GROWS_UP: Continuations. * stack_size: Continuations. * stat: I/O-Extensions. * STREAM: Ptob Cells. * string-edit: Regular Expression Pattern Matching. * string-split: Regular Expression Pattern Matching. * string-splitv: Regular Expression Pattern Matching. * STRINGP: Header Cells. * subwin: Window Manipulation. * SYMBOLP: Header Cells. * symlink: Unix Extensions. * sync: Unix Extensions. * syntax-quote: Syntactic Hooks for Hygienic Macros. * syntax-rules: Syntax Extensions. * tanh: Numeric. * terms: Miscellaneous Procedures. * the-macro: Syntactic Hooks for Hygienic Macros. * throw_to_continuation: Continuations. * ticks: Interrupts. * ticks-interrupt: Interrupts. * touchline: Window Manipulation. * touchwin: Window Manipulation. * trace: Debugging Scheme Code. * transpose-array: Conventional Arrays. * try-arbiter: Process Synchronization. * try-create-file: I/O-Extensions. * try-load <1>: Line Numbers. * try-load: Miscellaneous Procedures. * try-open-file: Files and Ports. * ttyname: Posix Extensions. * TYP16: Cells. * TYP3: Cells. * TYP7: Cells. * UCHARS: Header Cells. * ulong2num: Type Conversions. * umask: I/O-Extensions. * uname: Posix Extensions. * unctrl: Curses Miscellany. * uniform-array-read!: Uniform Array. * uniform-array-write: Uniform Array. * uniform-vector-fill!: Uniform Array. * untrace: Debugging Scheme Code. * user-interrupt: Interrupts. * usr:lib: Dynamic Linking. * utime: I/O-Extensions. * vector-set-length!: Miscellaneous Procedures. * VECTORP: Header Cells. * VELTS: Header Cells. * verbose: Internal State. * virtual-alarm: Interrupts. * virtual-alarm-interrupt: Interrupts. * vms-debug: SCM Session. * void: Sweeping the Heap. * wadd: Output. * wait-for-input: Files and Ports. * waitpid: Posix Extensions. * warn: Errors. * wclear: Output. * wclrtobot: Output. * wclrtoeol: Output. * wdelch: Output. * wdeleteln: Output. * werase: Output. * winch: Input. * winsch: Output. * winsertln: Output. * with-error-to-file: Files and Ports. * with-error-to-port: Files and Ports. * with-input-from-port: Files and Ports. * with-output-to-port: Files and Ports. * wmove: Window Manipulation. * wstandend: Curses Miscellany. * wstandout: Curses Miscellany. * x:lib: Dynamic Linking. Variable Index ************** This is an alphabetical list of all the global variables in SCM. * Menu: * $pi: Numeric. * *argv*: SCM Variables. * *execpath: Embedding SCM. * *interactive* <1>: Internal State. * *interactive*: SCM Variables. * *load-pathname*: Miscellaneous Procedures. * *load-reader*: Line Numbers. * *scm-version*: Internal State. * *slib-load-reader*: Line Numbers. * *syntax-rules*: SCM Variables. * af_inet: Host Data. * af_unix: Host Data. * BOOL_F: Immediates. * BOOL_T: Immediates. * EDITOR: SCM Variables. * EOF_VAL: Immediates. * EOL: Immediates. * errobj: Errors. * HOME: SCM Variables. * internal-time-units-per-second: Time. * INUM0: Immediates. * isymnames: Immediates. * most-negative-fixnum: Numeric. * most-positive-fixnum: Numeric. * NUM_ISPCSYM: Immediates. * NUM_ISYMS: Immediates. * open_both: Files and Ports. * open_read: Files and Ports. * open_write: Files and Ports. * pi: Numeric. * SCHEME_LIBRARY_PATH: SCM Variables. * SCM_INIT_PATH: SCM Variables. * symhash: Evaluation. * thrown_value: Continuations. * UNDEFINED: Immediates. * UNSPECIFIED: Immediates. Type Index ********** This is an alphabetical list of data types and feature names in SCM. * Menu: * #! <1>: MS-DOS Compatible Scripts. * #!: Unix Scheme Scripts. * array-for-each: Array Mapping. * CELLPTR: Immediates. * CONTINUATION: Continuations. * curses: Dynamic Linking. * dump: Dump. * FARLOC: Evaluation. * GLOC: Evaluation. * gloc: Immediates. * i/o-extensions: Socket. * ichr: Immediates. * iflags: Immediates. * ILOC: Evaluation. * iloc: Immediates. * inum: Immediates. * ispcsym: Immediates. * isym: Immediates. * meta-argument <1>: Script Support. * meta-argument: Unix Scheme Scripts. * ptob: Ptob Cells. * regex: Dynamic Linking. * rev2-procedures: Dynamic Linking. * rev3-procedures: Dynamic Linking. * Scheme Script <1>: MS-DOS Compatible Scripts. * Scheme Script: Unix Scheme Scripts. * Scheme-Script <1>: MS-DOS Compatible Scripts. * Scheme-Script: Unix Scheme Scripts. * smob: Smob Cells. * socket: Socket. * spare: Header Cells. * STACKITEM: Continuations. * tc16_arbiter: Smob Cells. * tc16_array: Smob Cells. * tc16_bigneg: Smob Cells. * tc16_bigpos: Smob Cells. * tc16_flo: Smob Cells. * tc16_inpipe: Ptob Cells. * tc16_inport: Ptob Cells. * tc16_ioport: Ptob Cells. * tc16_macro: Smob Cells. * tc16_outpipe: Ptob Cells. * tc16_outport: Ptob Cells. * tc16_promise: Smob Cells. * tc16_sfport: Ptob Cells. * tc16_strport: Ptob Cells. * tc3_closure: Cells. * tc3_cons: Cells. * tc7_asubr: Subr Cells. * tc7_bvect: Header Cells. * tc7_contin: Header Cells. * tc7_cvect: Header Cells. * tc7_cxr: Subr Cells. * tc7_dvect: Header Cells. * tc7_fvect: Header Cells. * tc7_ivect: Header Cells. * tc7_lsubr: Subr Cells. * tc7_lsubr_2: Subr Cells. * tc7_msymbol: Header Cells. * tc7_rpsubr: Subr Cells. * tc7_specfun: Header Cells. * tc7_ssymbol: Header Cells. * tc7_string: Header Cells. * tc7_subr_0: Subr Cells. * tc7_subr_1: Subr Cells. * tc7_subr_1o: Subr Cells. * tc7_subr_2: Subr Cells. * tc7_subr_2o: Subr Cells. * tc7_subr_3: Subr Cells. * tc7_svect: Header Cells. * tc7_uvect: Header Cells. * tc7_vector: Header Cells. * tc_dblc: Smob Cells. * tc_dblr: Smob Cells. * tc_free_cell: Smob Cells. * turtle-graphics: Dynamic Linking. * unexec: Dump. This is an alphabetical list of concepts introduced in this manual. Concept Index ************* * Menu: * !#: MS-DOS Compatible Scripts. * !#.exe: MS-DOS Compatible Scripts. * #!: MS-DOS Compatible Scripts. * #!.bat: MS-DOS Compatible Scripts. * array <1>: Conventional Arrays. * array: Build Options. * array-for-each: Build Options. * arrays: Build Options. * bignums: Build Options. * callbacks: Callbacks. * careful-interrupt-masking: Build Options. * cautious: Build Options. * cheap-continuations: Build Options. * compiled-closure: Build Options. * continuations: Continuations. * curses: Build Options. * debug: Build Options. * documentation string: Syntax Extensions. * dump: Build Options. * dynamic-linking: Build Options. * ecache: Memory Management for Environments. * edit-line: Build Options. * Embedding SCM: Embedding SCM. * engineering-notation: Build Options. * environments: Memory Management for Environments. * exchanger: Process Synchronization. * Exrename: Bibliography. * Extending Scm: Compiling and Linking Custom Files. * foo.c: Compiling and Linking Custom Files. * generalized-c-arguments: Build Options. * graphics: Packages. * hobbit: Packages. * i/o-extensions: Build Options. * IEEE: Bibliography. * inexact: Build Options. * JACAL: Bibliography. * lit: Build Options. * macro: Build Options. * memory management: Memory Management for Environments. * mysql: Build Options. * no-heap-shrink: Build Options. * NO_ENV_CACHE: Memory Management for Environments. * none: Build Options. * posix: Build Options. * R4RS: Bibliography. * R5RS: Bibliography. * reckless: Build Options. * record: Build Options. * regex: Build Options. * rev2-procedures: Build Options. * SchemePrimer: Bibliography. * SICP: Build Options. * sicp: Build Options. * SICP: Bibliography. * signals: Signals. * Simply: Bibliography. * single-precision-only: Build Options. * SLIB: Bibliography. * socket: Build Options. * stack-limit: Build Options. * tick-interrupts: Build Options. * turtlegr: Build Options. * unix: Build Options. * windows: Build Options. * X: Packages. * x <1>: Packages. * x: Build Options. * xlib: Packages. * Xlib: Packages. * xlib: Build Options. * xlibscm: Packages. * Xlibscm: Packages.  Tag Table: Node: Top203 Node: Overview1426 Node: SCM Features1737 Node: SCM Authors3749 Node: Copying4645 Node: Bibliography7730 Node: Installing SCM9598 Node: Making SCM10113 Node: SLIB11030 Node: Building SCM12945 Node: Invoking Build13519 Node: Build Options15793 Node: Compiling and Linking Custom Files27939 Node: Installing Dynamic Linking29902 Node: Configure Module Catalog31686 Node: Saving Images33683 Node: Automatic C Preprocessor Definitions34358 Node: Problems Compiling37629 Node: Problems Linking39282 Node: Problems Running39547 Node: Testing41622 Node: Reporting Problems44659 Node: Operational Features45504 Node: Invoking SCM45868 Node: SCM Options47473 Node: Invocation Examples51745 Node: SCM Variables52697 Node: SCM Session54127 Node: Editing Scheme Code55465 Node: Debugging Scheme Code57608 Node: Errors61231 Node: Memoized Expressions65459 Node: Internal State67815 Node: Scripting70895 Node: Unix Scheme Scripts71189 Node: MS-DOS Compatible Scripts74401 Node: Unix Shell Scripts76213 Node: The Language78403 Node: Standards Compliance78995 Node: Miscellaneous Procedures81409 Node: Time84509 Node: Interrupts85503 Node: Process Synchronization90581 Node: Files and Ports92118 Node: Line Numbers97992 Node: Soft Ports100234 Node: Syntax Extensions102032 Node: Low Level Syntactic Hooks111007 Node: Syntactic Hooks for Hygienic Macros116212 Node: Packages123186 Node: Dynamic Linking123988 Node: Dump128597 Node: Numeric132606 Node: Arrays134333 Node: Conventional Arrays134543 Node: Array Mapping141171 Node: Uniform Array143397 Node: Bit Vectors148645 Node: Records149910 Node: I/O-Extensions150773 Node: Posix Extensions159362 Node: Unix Extensions169048 Node: Regular Expression Pattern Matching170950 Node: Line Editing174904 Node: Curses176250 Node: Output Options Setting177173 Node: Terminal Mode Setting179822 Node: Window Manipulation182900 Node: Output186360 Node: Input189986 Node: Curses Miscellany191013 Node: Sockets192437 Node: Host Data192761 Node: Internet Addresses and Socket Names195909 Node: Socket197443 Node: The Implementation204680 Node: Data Types204939 Node: Immediates205760 Node: Cells210096 Node: Header Cells212188 Node: Subr Cells215229 Node: Ptob Cells217447 Node: Smob Cells218986 Node: Data Type Representations222182 Node: Operations226835 Node: Garbage Collection227421 Node: Marking Cells228042 Node: Sweeping the Heap230144 Node: Memory Management for Environments231089 Node: Signals235646 Node: C Macros237190 Node: Changing Scm238313 Node: Defining Subrs242572 Node: Defining Smobs244449 Node: Defining Ptobs247495 Node: Allocating memory248672 Node: Embedding SCM250985 Node: Callbacks258587 Node: Type Conversions260330 Node: Continuations263886 Node: Evaluation268100 Node: Program Self-Knowledge273263 Node: File-System Habitat273509 Node: Executable Pathname277109 Node: Script Support278713 Node: Improvements To Make280031 Node: Finishing Dynamic Linking282063 Node: Index289809  End Tag Table