Scream

Scream is a simple dialect of Lisp written in ruby. It's an incomplete subset of Scheme, supporting no syntactic sugar (yet). This is the second Scheme subset I've ever written, so please for the love of god don't use this for anything real.

Built-in Functions

The following operations are built in:

• Common numeric operations, e.g. +, -, *, /, =, modulo, quotient and expt.
• The unary boolean operator, not
• The list manipulation functions, car, cdr, cons and null?
• Hashtables (from Ruby's builtin hash), hash, get, and put
• Ruby FFI: new, ., and reval.

Built-in Syntax

Additionally, the following syntactic tokens are valid

• define (defines a variable)
• set (set's a variables value)
• lambda (creates an anonymous function)
• quote (quote's a value)
• debug (prints the current environment to stdout)
• if (basic conditional)
• begin (for sequencing)

To Do

• Create expansion phase
• a define-macro-like form (simple once expansion takes place in its own phase)
• Add more synactic forms
  • let and friends
  • cond
  • and / or
  • quasiquote, unquote, unquote-splicing (already supported in the lexer and parser, just need to write the expansion phase)
• Extend the FFI somewhat (or at least fix the bugs)