PyScheme

A Scheme Interpreter Implemented in Python with Starter Code from the CS 61A Scheme Challenge Version Project.

Only covers features within the project (including optional ones).

Usage

In a Terminal, set the current directory to be the folder scheme_stubbed, and then type:

python3 scheme.py

The Scheme prompt will show as:

scm> 

To exit the Scheme interpreter, press Ctrl-D or evaluate the exit procedure:

scm> (exit)

Examples

scm> +
#[+]
scm> odd?
#[odd?]
scm> display
#[display]

scm> (+ 1 2)
3
scm> (* 3 4 (- 5 2) 1)
36
scm> (odd? 31)
#t

scm> (define x 15)
x
scm> x
15
scm> (eval 'x)
15
scm> (define y (* 2 x))
y
scm> y
30
scm> (+ y (* y 2) 1)
91
scm> (define x 20)
x
scm> x
20

scm> (quote a)
a
scm> (quote (1 2))
(1 2)
scm> (quote (1 (2 three (4 5))))
(1 (2 three (4 5)))
scm> 'hello
hello
scm> (eval (cons 'car '('(1 2))))
1

Reference

CS 61A

Scheme Challenge Version