stjordanis/lispy-1

A LISP interpreter in Python

LisPy README

Author: Kemal Eren ([email protected])

ABOUT

LisPy is an implementation of a subset of the features of LISP 1.5, as outlined in John McCarthy's LISP 1.5 Programmer's Manual.

The following primitives are defined:

• T
• NIL
• CAR
• CDR
• CONS
• ATOM
• EQ
• NULL
• INT
• PLUS
• MINUS
• TIMES
• QUOTIENT
• REMAINDER
• LESS
• GREATER
• COND
• QUOTE
• DEFUN
• HELP
• QUIT

and various math symbols: + - % * / = < >

LisPy supports both interactive and batch modes.

REQUIREMENTS

• Python (tested with 2.6 and 2.7)

USAGE

NB: LisPy is case-insensitive, and allows both dot and list notation (though they may not be mixed).

See demo.lsp for some simple examples.

Interactive mode:

In interactive mode, individual LISP commands may be entered into the REPL (read-eval-print loop).

Simply run ./interpreter.py to start an interactive toplevel. LISP commands may be entered over multiple lines; a command will not be evaluated until the parentheses match.

Pressing "Control+c" abandons the current expression and starts a new line. Calling (help) gives some minimal help.

When finished, type (quit) or press "Control+d" to exit.

Batch mode

Run ./interpreter.py <input file>. All expressions in the file will be read, evaluated, and printed in order to standard output.