Lambda the Ultimate

I've just released a major new version of the Cat programming language, and an extension called MetaCat. The most recent release can be downloaded through Google code hosting.

Cat is a statically typed functional stack-based language, based on the Joy programming language. Cat was designed primarily as a high-level intermediate language for the translation, verification, and optimization of programs written in multi-paradigm languages. Cat also is intended for use as a language for teaching core computer science and programming concepts.

The MetaCat language extends Cat with a term rewriting system which was based on Manfred von Thun's paper A Rewriting System for Joy and is similar to the
GHC Rewrite Rules.

Cat has the following features:

• strongly typed - all expressions have a well-defined type
• side-effect labeling - functions with side-effects are typed differently from pure function
• purity - the level 0, level 1, and level 2, of the Cat specification are entirely with side-effects. Side-effects in the rest of the Cat language are managed by the type system.
• minimal syntactic constructs - apart from function and macro definition syntax, the only syntactic constructs with predefined meaning are the quotation operators "[" and "]"
• point-free form - the core language has no named parameters or variables
• polymorphic variants - the "var" type allows dynamic dispatching based on type
• type inference - type annotations are optional
• typed exceptions - exceptions can be thrown and caught in a type safe manner

Features of the release:

• a Cat to Common Intermediate Language (CIL a.k.a. MSIL) compiler
• sub-expression evaluator
• function call inline expansion
• over 500 unit tests
• basic graphic capabilities
• over 250 documented built-in and library defined primitive functions
• multi-tiered specificiation that allows different levels of compatibility with the standard
• over 200 library defined optimization rules
• the interpreter is released under the MIT license, but the source code is released into the public domain.
• written in Mono-compatible C#
• a simple converter from a variant of Cat with named parameters called Kitten to the standard point-free Cat.

A big thank you to the many members of the Lambda-the-Ultimate community whose constributions and insights have been instrumental in the development of the Cat language. Any questions, comments, or requests would be much appreciated.