pipes-parse builds upon the pipes library to provide shared streaming parsing utilities.

• Install the Haskell Platform
• cabal install pipes-parse

Then fire up ghci:

Prelude> import Pipes
Prelude Pipes> import qualified Pipes.Prelude as P
Prelude Pipes P> import qualified Pipes.Parse as P

... and limit standard input to first three consecutive groups of equal lines:

Prelude Pipes P P> let threeGroups = P.concat . P.takeFree 3 . P.groupBy (==)
Prelude Pipes P P> runEffect $ threeGroups P.stdinLn >-> P.stdoutLn
Group1<Enter>
Group1
Group1<Enter>
Group1
Group2<Enter>
Group2
Group3<Enter>
Group3
Group3<Enter>
Group3
Group4<Enter>
Prelude Pipes P P> -- Done, because we began entering our fourth group

The official tutorial is on Hackage.

• Perfect Streaming: Program in a list-like style in constant memory

• Concise Parsing API: Just use draw and unDraw or input

• Leftovers: Save unused input for later consumption

• Connect and Resume: Use StateT to save unused input for later

• Termination Safety: Detect and recover from end of input

pipes-parse provides generic examples for how to parse streams using pipes. Datatype-specific parsers belong in separate libraries. The purpose behind this library is to provide example idioms that other libraries can reuse, as well as providing useful tools for generic stream parsing. Typically, stream-specific parsing libraries will need to redefine specialized versions of the primitives in this library and will probably not need to depend on pipes-parse at all.

pipes-parse is close to complete and will probably add a few more functions over the new few months. If the API does not make any backwards incompatible changes by the end of 2013 then the library will be officially stabilized.

Use the same resources as the core pipes library to learn more, contribute, or request help:

• Haskell wiki page

• Mailing list (Google Group)

• Build derived libraries

• Write pipes-parse tutorials

Copyright (c) 2013 Gabriel Gonzalez All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

• Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

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