@hackage first-class-patterns0.3.2.3

This package implements a library of first class patterns. The initial basis for this library was Morten Rhiger's "Type-safe pattern combinators"; the patterns can be used in an almost identical way to those of Morten Rhiger. In a series of blog posts at http://reinerp.wordpress.com/category/pattern-combinators/ the types of patterns were made more revealing using type families, and a simpler implementation was used which avoids some book-keeping.

The library reimplements most of Haskell's built-in pattern matching facilities, plus some more. The pattern matches of this library are lightweight: when GHC's optimisation is turned on, all overhead should be optimised away, leaving a standard Haskell pattern match.

If you're just reading the documentation for this library for the first time, start with Data.Pattern.