weighted-regexp

This is a Rust implementation of the ideas from "A Play on Regular Expressions". Initially I more-or-less followed the Python treatment of the same ideas from "An Efficient and Elegant Regular Expression Matcher in Python", and then I've added support for weights.

This is not ready for real use: test coverage is minimal, and the interface for constructing and matching regular expressions is inconvenient.

However, this does illustrate that Rust can do (almost) everything that the original paper needed from Haskell, so it should be possible to duplicate all of the paper's results.