MIT Scheme pointers

Some of the functions listed below assume you have installed the CS441 Scheme extensions.

Useful REPL commands

(load "file.scm") executes the Scheme expressions in "file.scm"
(pwd) prints the current working directory
(cd "wherever") changes the current working directory

Dealing with Errors

The Scheme prompt includes a number that increments as you make errors. If you are brave, you can refer to these numbers with the debugger to investigate context at different errors. C-c C-c pops and discards one level of error context, in both the ordinary REPL and under Emacs.

Useful Functions and Special Forms

(printf format-string arg ...) is like C's printf, except that the escape characters are different:
- ~% is a newline
- ~a inserts an argument value (of any type)
(define-record name (field ...)) builds the following abstract representation functions:
- make-name - constructor
- name? - predicate
- name->field ... - selectors
(variant-case exp (name (field ...) exp ...) ...) pattern matches on records (see EOPL).
extend-syntax adds new syntactic forms (see EOPL).