Parsec

Introduction

Parsec is an industrial strength, monadic parser combinator library for Haskell. It can parse context-sensitive, infinite look-ahead grammars but it performs best on predictive (LL[1]) grammars.

The latest stable release with Haddock documentation is available on Hackage and development versions are available via the darcs repository.

Usage

Parsec lets you construct parsers by combining higher-order Combinators to create larger expressions. Combinator parsers are written and used within the same programming language as the rest of the program. The parsers are first-class citizens of the language , unlike Happy parsers, which must be generated via a preprocessor.

An example for parsing a simple grammar of expressions can be found here.

Much more documentation can be found on the parsec website.

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Examples

• "Using Parsec" chapter on Real World Haskell.

• Write Yourself a Scheme in 48 Hours/Parsing. Note, that where the example uses the read function, the Token module of Parsec could have been used, to handle numbers.

See also the list of reversed dependencies for Parsec.

Parsec clones in other languages

• PCL for O'Caml http://lprousnth.files.wordpress.com/2007/08/pcl.pdf
• JParsec for Java http://jparsec.codehaus.org/JParsec+Overview
• NParsec, JParsec ported to C# http://jparsec.codehaus.org/NParsec+Tutorial
• Ruby Parsec, JParsec ported to Ruby http://jparsec.codehaus.org/Ruby+Parsec
• FParsec for F# http://www.quanttec.com/fparsec/
• Parsec-Erlang, http://bitbucket.org/dmercer/parsec-erlang/ is a faithful reproduction of Parsec in Erlang (there is also an older toy Parsec-like parser that isn't monadic, nor does it give error messages: http://www.engr.uconn.edu/~jeffm/Source/Erlang/)
• AliceParsec for Alice ML http://www.ps.uni-sb.de/alice/contribs.html
• Parsnip for C++ http://parsnip-parser.sourceforge.net/
• Somewhere there is a Nemerle port
• Pysec for Python http://www.valuedlessons.com/2008/02/pysec-monadic-combinatoric-parsing-in.html
• JSParsec for JavaScript: http://code.google.com/p/jsparsec/

Interesting non-Parsec parser combinator libraries:

• Spirit for C++ http://spirit.sourceforge.net/documentation.html

Links

Docs

• on Parsec website
• on Microsoft (content same as above)

Blog articles

• Adventures in parsing
• More adventures in parsing
• Adventures in parsing, part 3
• Adventures in parsing, part 4