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+============================
+The Little Schemer
+============================
+
+:by: Daniel Friedman and Matthias Felleisen 
+:Edition: Fourth (4rth)
+
+See also `Scheme </k/software/scheme/>`__.
+
+I read this book before starting on a scheme/physics project. I had programmed
+in scheme previously as an algebra/analysis tool, but never really sat down
+and got comfortable with the language. Working through all the examples
+has made me *much* more comfortable with this style of programming. Despite
+the humble tone and ambitions of the book I think I learned deeply.
+
+The first 7 chapters were very straight forward, the end of chapter 8 took 
+some more thought and I'm not sure how happy I am with the description of
+collectors and continuations.
+
+For a better description of the Y-combinator, see these `course notes 
+<http://dangermouse.brynmawr.edu/cs245/ycomb_jim.html>`__.
+
+This book is followed by `The Seasoned Schemer </k/books/seasonedschemer/>`__
+and The Reasoned Schemer.
+
+Preface Definitions
+------------------------
+This primitive function is required for most of the functions in the book::
+
+    (define atom?
+      (lambda (x)
+        (and (not (pair? x)) (not (null? x)))))
+
+Laws
+-----------------------
+Law of Car
+    The primitive *car* is defined only for non-empty lists.
+ 
+Law of Cdr
+    The primitive *cdr* is defined only for non-empty lists. The *cdr* of any 
+    non-empty list is always another list.
+
+Law of Cons
+    The primitive *cons* takes two arguments. The second argument to *cons* 
+    must be a list. The result is a list.
+
+Law of Null?
+    The primitive *null?* is defined only for lists.
+
+Law of Eq?
+    The primitive *eq?* takes two arguments. Each must be a non-numeric atom.
+
+Commandments
+------------------------
+
+The First Commandment
+    When recurring on a list of atoms, *lat*, ask two questions about it:
+    *(null? lat)* and **else**. When recurring on a number, *n*, ask two
+    questions about it: *(zero? n)* and **else**.
+
+    When recurring on a list of S-expressions, *l*, ask three questions
+    about it: *(null? l)*, *(atom? (car l))*, and **else**.
+
+The Second Commandment
+    Use *cons* to build lists.
+
+The Third Commandment
+    When building a list, describe the first typical element, and then
+    *cons* it onto the natural recursion.
+
+The Fourth Commandment
+    Always change at least one argument while recurring. It must be changed to 
+    be closer to termination. The changing argument must be tested in the 
+    termination condition: 
+
+    when using *cdr*, test termination with *null?* and
+
+    when using *sub1*, test termination with *zero?*.
+
+The Fifth Commandment
+    When building a value with +, always use 0 for the value of the terminating
+    line, for adding 0 does not change the value of an addition.
+    
+    When building a value with x, always use 1 for the value of the terminating
+    line, for multiplying by 1 does not change the value of a multiplication.
+    
+    When building a value with cons, always consider () for the value of the
+    terminating line.
+
+The Sixth Commandment
+    Simplify only after the function is correct.
+
+
+The Seventh Commandment
+    Recur on the subpart that are of the same nature:
+
+    * on the sublists of a list.
+    * on the subexpressions of an arithmetic expression.
+
+The Eighth Commandment
+    Use help functions to abstract from representations.
+
+The Ninth Commandment
+    Abstract common patterns with a new function.
+
+The Tenth Commandment
+    Build functions to collect more than one value at a time.
+
diff --git a/books/Seasoned Schemer b/books/Seasoned Schemer
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+============================
+The Seasoned Schemer
+============================
+
+:by: Daniel Friedman and Matthias Felleisen 
+:Edition: First (1st) 
+
+See also `Scheme </k/software/scheme/>`__. This book is a sequel 
+to `The Little Schemer`_; The Reasoned Schemer is a paralel exploration of 
+logical programming.
+
+One of the things I liked about learning a programming language this way, or
+maybe just about scheme in general, is the seperation between the specification
+and implementations. Usually when I start learning a new language I try to 
+break it as fast as possible and I am most interested in how certain little
+tricky bits are handled (are the file handles cross platform? does it catch
+infinite recursion? what kind of errors are thrown when? how big are the 
+primitives and simple objects/user defined data types?). These are the
+imporant day to day issues and are a good basis for choosing a language to get
+work done in, but it's kind of like searching for anti-aliasing in digital
+photos or scanning the edges of a wall for painting mistakes. Sometimes the
+big picture is the whole point and it's worth putting up with small flaws.
+
+.. _The Little Schemer: /k/books/littleschemer/
+
+Issues/Omissions 
+--------------------------
+The Y combinator function is never defined in this book, I had to copy it out of 
+`The Little Schemer`_; 
+
+    (define Y
+      (lambda (thing)
+        ((lambda (le)
+           ((lambda (f) (f f))
+            (lambda (f) (le (lambda (x) ((f f) x))))))
+         thing)))
+
+Also ``eqlist?``::
+
+    (define eqlist?
+      (lambda (a b)
+        (cond
+         ((and (null? a) (null? b)) #t)
+         ((or (null? a) (null? b)) #f)
+         ((and (atom? (car a)) (atom? (car b)))
+	       (and (eqlist? (cdr a) (cdr b))))
+         ((or (atom? (car a)) (atom? (car b))) #f)
+         (else (and (eqlist? (car a) (car b)) (eqlist? (cdr a) (cdr b)))))))
+
+MIT/GNU Scheme doesn't seem to have ``letcc`` or ``try``; I stuck with
+``call-with-current-continuation``:
+
+    (call-with-current-continuation (lambda (hook) ...)
+    ; is the same as
+    (letcc hook (...))
+
+    ; as noted in the book (p. 89)
+    (try x a b)
+    ; is the same as
+    (letcc success 
+      (letcc x 
+        (success a)) 
+      b)
+    ; is the same as
+    (call-with-current-continuation 
+      (lambda (success)
+        (begin
+          (call-with-current-continuation
+            (lambda (x)
+              (success a)))
+          b)))
+
+When reimplementing scheme at the end of the book, I'm kind of miffed that the
+(letcc ...) definition basically just uses letcc, because magic North Pole
+compasses seem like the most interesting part.
+
+Notes
+-----------------
+Y-bang is the "applicative-order imperative Y combinator"::
+
+    (define Y-bang
+      (lambda (f)
+        (letrec
+	    ((h (f (lambda (arg) (h arg)))))
+          h)))
+
+At one point I wondered::
+
+    Is there any language/interpreter which, when it runs into an undefined
+    value, lets you define it on the spot? Would be great for learners.
+
+MIT/GNU Scheme, of course, has this feature in the error REPL. But I never
+noticed it.
+
+The Next 10 Commandments
+--------------------------
+
+The Eleventh Commandment
+    Use additional arguments when a function needs to know what other 
+    arguments to the function have been like so far.
+
+The Twelfth Commandment
+    Use (letrec ..) to remove arguments that do not change for 
+    recursive applications.
+
+The Thirteenth Commandment
+    Use (letrec ...) to hide and protect functions.
+
+The Fifteenth Commandment
+    Use (let ...) to name the values of repeated expressions in a function
+    definition if they may be evaluated twice for one and same use of the
+    function. And use (let ...) to name the values of expressions (without
+    set!) that are re-evaluated every time a function is used.
+
+The Sixteenth Commandment
+    Use (set! ...) only with names define in (let ...)s
+
+The Seventeenth Commandment
+    Use (set! x ...) for (let ((x ..)) ..)) only if there is at least one
+    (lambda .. between it and the (let ..), or if the new value for x is a 
+    function that refers to x.
+
+The Eighteenth Commandment
+    Use (set! x ...) only when the value that x refers to is no longer needed.
+
+The Nineteenth Commandment
+    Use (set! ...) to remember valuable things between two distinct uses of a 
+    function.
+
+The Twentieth Commandment
+    When thinking about a value created with (letcc ...), write down the
+    function that is equivalent but does not forget. Then, when you use it,
+    remember to forget.
+
+**I love that last sentence!**
+
+
+
+