dumb-cas

A computer “algebra” system that knows nothing about algebra, at the core.

This is a framework for untyped, symbolic computations like a CAS does, without any baked-in rules whatsoever but the ability to define expressions very consisely, as well as any transformation rules you want. The idea is basically to combine the flexibility of a Lisp with the conciseness of a Regex engine, using syntax similar to Haskell's standard pattern matching.