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 (Happy.Grammar)

• A parser for happy grammar files (.y) to produce a Grammar (Happy.Frontend.*)

• Implementations of the text book algorithms that compute the LR action and goto tables for the given Grammar (Happy.Tabular.*)

• An LALR code generator to produce table-driven, deterministic parsing code in Haskell (Happy.Backend.LALR.*)

• A (less maintained) GLR code generator to produce table-driven, non-deterministic parsing code in Haskell, where ambiguous parses produce multiple parse trees (Happy.Backend.GLR.*)

---

[Skip to Readme]

library happy-lib

library happy-lib:backend-glr

library happy-lib:backend-lalr

library happy-lib:tabular

library happy-lib:frontend

library happy-lib:grammar

Downloads

• happy-lib-2.0.tar.gz [browse] (Cabal source package)
• Package description (as included in the package)

Maintainer's Corner

Package maintainers

• AndreasAbel, IavorDiatchki, JohnEricson, SimonMarlow, int_index, sgraf812

For package maintainers and hackage trustees

• edit package information

Candidates

• 2.0, 2.0.1, 2.0.2, 2.1, 2.1.1, 2.1.2, 2.1.3