Log message:
Added perl to USE_TOOLS.

Log message:
Replaced SITES_* with SITES.*.

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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).