Happy is a parser generator for Haskell. Given a grammar specification
in BNF, Happy generates Haskell code to parse the grammar. Happy
works in a similar way to the yacc tool for C.

This library provides the following functionality:

* Data type definitions for the Grammar AST type, capturing the
  information in .y-files
* A parser for happy grammar files (.y) to produce a Grammar
* Implementations of the text book algorithms that compute the LR
  action and goto tables for the given Grammar
* An LALR code generator to produce table-driven, deterministic
  parsing code in Haskell
* A (less maintained) GLR code generator to produce
  table-driven, non-deterministic parsing code in Haskell, where
  ambiguous parses produce multiple parse trees

Homepage:
http://hackage.haskell.org/package/happy-lib
