Log Message:
Happy is a parser generator system for Haskell, similar to the tool
`yacc' for C. Like `yacc', it takes a file containing an annotated BNF
specification of a grammar and produces a Haskell module containing a
parser for the grammar.

Happy is flexible: you can have several Happy parsers in the same
program, and several entry points to a single grammar. Happy can work
in conjunction with a lexical analyser supplied by the user (either
hand-written or generated by another program), or it can parse a
stream of characters directly (but this isn't practical in most
cases).