An umptieth repository of solutions to most exercises from Abelson and Sussman’s Structure and Interpretation of Computer Programs.
Link to PDF file with explanations (and code):
SICP-Solutions.pdf. Looking in this file is probably the
most convenient way to see how I solved a particular exercise (especially for
the more complex ones): the .scm files don’t contain explanations since I put
them in the PDF, and sometimes an exercise is split into several parts because
it was more convenient to explain the parts separately.
The files named <exercise-number>pre.scm contain code from the book that
precedes the exercise with the given number, or sometimes code from the text of
the exercise. In most cases, the files named
<exercise-number><optional-letter>.scm only contain the code written or
changed to solve the exercise, not all the code the solution depends on.
To run the code, it’s often necessary to load multiple files, which is done by
files generally named <something>-test.scm (not because they contain tests but
because I used them to easily load and try out the code in the REPL). If you are
here you probably want to compare your solutions to mine, or maybe you are stuck
and want a hint to be able to write your own solution, so I guess trying out my
code is not your main concern :-).
I used Gambit Scheme for most exercises, the most
notable exception being section 2.2.4 about the picture language, for which
I used Racket and the graphics.ss library. Some of
the code is not compatible with other interpreters, notably the definition of
the macros for the streams and the functions for generating random numbers, but
the changes needed to use another interpreter should be limited.