[Haskell] ANNOUNCE: Frown - an LALR(k) Parser Generator for Haskell (version 0.6, beta)

Ralf Hinze ralf at informatik.uni-bonn.de
Tue Nov 1 15:48:47 EST 2005

I'm pleased to announce the first release of Frown (version 0.6,
andromeda release), an LALR(k) Parser Generator for Haskell 98.
This is a beta quality release.

Frown's salient features are:

o  The generated parsers are time and space efficient. On the downside,
   the parsers are quite large.

o  Frown generates four different types of parsers. As a common
   characteristic, the parsers are genuinely functional (ie `table-free');
   the states of the underlying LR automaton are encoded as mutually
   recursive functions. Three output formats use a typed stack
   representation, one format due to Ross Paterson (code=stackless)
   works even without a stack.

o  Encoding states as functions means that each state can be treated
   individually as opposed to a table driven-approach, which
   necessitates a uniform treatment of states. For instance,
   look-ahead is only used when necessary to resolve conflicts.

o  Frown comes with debugging and tracing facilities; the standard
   output format due to Doaitse Swierstra (code=standard) may be
   useful for teaching LR parsing.

o  Common grammatical patterns such as repetition of symbols can be
   captured using rule schemata. There are several predefined rule

o  Terminal symbols are arbitrary variable-free Haskell patterns or
   guards. Both terminal and nonterminal symbols may have an arbitrary
   number of synthesized attributes.

o  Frown comes with extensive documentation; several example grammars
   are included.

Furthermore, Frown supports the use of monadic lexers, monadic
semantic actions, precedences and associativity, the generation of
backtracking parsers, multiple start symbols, error reporting and a
weak form of error correction.

Frown is available in source form, which can be compiled with GHC
version 5.02+. The source code and further information is available
on the Frown home page


Please send any bug reports and comments to ralf at informatik.uni-bonn.de.

Happy frowning, Ralf

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