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To get a feel for what real world Haskell looks like, here are some
 
To get a feel for what real world Haskell looks like, here are some
examples from various popular Haskell projects. Good places to start
+
examples from various popular [[Libraries_and_tools|Haskell projects]].
learning Haskell are [[Learning_Haskell|here]],
+
To start learning the language, good places to start are
[[Haskell_in_5_steps|here]] and [[Books_and_tutorials|here]].
+
[[Learning Haskell]],
  +
[[Haskell in 5 steps]], and
  +
[[Books and tutorials]].
  +
  +
More code may be found [http://www.haskell.org/haskellwiki/Category:Code on the wiki].
  +
  +
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Some lines are commented out for later update
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=== Library code ===
 
=== Library code ===
   
 
Library code usually differs from application code: it is often highly
 
Library code usually differs from application code: it is often highly
structured, and documented with [http://haskell.org/haddock haddock],
+
structured, and documented with [http://www.haskell.org/haddock/ haddock],
 
and can be rather optimised. Some instructive examples (syntax
 
and can be rather optimised. Some instructive examples (syntax
 
highlighting by [http://www.cs.york.ac.uk/fp/darcs/hscolour/ hscolour]):
 
highlighting by [http://www.cs.york.ac.uk/fp/darcs/hscolour/ hscolour]):
   
* [http://www.cse.unsw.edu.au/~dons/data/Prelude.html A Haskell 98 Prelude.hs], foundational Haskell library ([http://www.cse.unsw.edu.au/~dons/data/Prelude.hs raw])
+
* [http://www.haskell.org/ghc/docs/latest/html/libraries/base/src/Prelude.html A Haskell Prelude.hs], foundational Haskell library ([http://www.haskell.org/ghc/docs/latest/html/libraries/base/Prelude.html docs])
* [http://www.cse.unsw.edu.au/~dons/data/List.html List.hs], the standard list library ([http://www.cse.unsw.edu.au/~dons/data/List.hs raw])
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* [http://www.cse.unsw.edu.au/~dons/data/Maybe.html Maybe.hs], the <code>Maybe</code> type ([http://www.cse.unsw.edu.au/~dons/data/Maybe.hs raw])
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* [[Simple_Unix_tools | Unix.hs]], simple unix tools, for beginner Haskellers
* [http://www.cse.unsw.edu.au/~dons/data/Map.html Map.hs], the standard finite map ([http://darcs.haskell.org/packages/base/Data/Map.hs raw])
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* [http://www.cse.unsw.edu.au/~dons/data/Graph.html Graph.hs], a graph type ([http://darcs.haskell.org/packages/base/Data/Graph.hs raw])
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* [http://hackage.haskell.org/packages/archive/base/latest/doc/html/src/Data-List.html List.hs], the standard list library ([http://hackage.haskell.org/packages/archive/base/latest/doc/html/Data-List.html docs])
* [http://www.cse.unsw.edu.au/~dons/data/Monad.html Monad.hs], basic monad support ([http://darcs.haskell.org/packages/base/Control/Monad.hs raw])
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* [http://www.cse.unsw.edu.au/~dons/data/QuickCheck.html QuickCheck.hs], a testing framework ([http://darcs.haskell.org/packages/QuickCheck/Test/QuickCheck.hs raw])
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* [http://hackage.haskell.org/packages/archive/base/latest/doc/html/src/Data-Maybe.html Maybe.hs], the <code>Maybe</code> type ([http://hackage.haskell.org/packages/archive/base/latest/doc/html/Data-Maybe.html docs])
* [http://www.cse.unsw.edu.au/~dons/data/HughesPJ.html PrettyPrint.hs], a pretty printing library ([http://darcs.haskell.org/packages/base/Text/PrettyPrint/HughesPJ.hs raw])
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* [http://www.cse.unsw.edu.au/~dons/data/State.html State.hs], a state monad ([http://darcs.haskell.org/packages/mtl/Control/Monad/State.hs raw])
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* [http://hackage.haskell.org/packages/archive/containers/latest/doc/html/src/Data-Map.html Map.hs], the standard finite map ([http://www.haskell.org/ghc/docs/latest/html/libraries/containers-0.4.2.1/index.html docs])
* [http://www.cse.unsw.edu.au/~dons/data/Music.html Music.hs], a music composition system (literate latex-style Haskell) ([http://darcs.haskell.org/haskore/src/Haskore/Music.lhs raw])
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  +
* [http://hackage.haskell.org/packages/archive/containers/latest/doc/html/src/Data-Graph.html Graph.hs], a graph type ([http://hackage.haskell.org/packages/archive/containers/latest/doc/html/Data-Graph.html docs])
  +
  +
* [http://hackage.haskell.org/packages/archive/base/latest/doc/html/src/Control-Monad.html Monad.hs], basic monad support ([http://hackage.haskell.org/packages/archive/base/latest/doc/html/Control-Monad.html docs])
  +
  +
* [http://code.haskell.org/QuickCheck/stable/Test/QuickCheck/ QuickCheck], a testing framework ([http://hackage.haskell.org/package/QuickCheck docs])
  +
  +
* [http://hackage.haskell.org/packages/archive/pretty/latest/doc/html/src/Text-PrettyPrint-HughesPJ.html PrettyPrint.hs], a pretty printing library ([http://hackage.haskell.org/package/pretty docs])
  +
  +
* [http://hackage.haskell.org/packages/archive/transformers/latest/doc/html/src/Control-Monad-Trans-State-Lazy.html State.hs], a state monad ([http://hackage.haskell.org/packages/archive/transformers/latest/doc/html/Control-Monad-Trans-State-Lazy.html docs])
  +
<!--
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* [http://www.cse.unsw.edu.au/~dons/data/Music.html Music.hs], a music composition system (literate latex-style Haskell) ([http://darcs.haskell.org/haskore/src/Haskore/Music.lhs raw], [http://www.haskell.org/haskore/ home])
  +
-->
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* [http://www.ninebynine.org/Software/Swish-0.2.1/HaskellRDF/Dfa/Dfa.lhs Dfa.lhs], finite automata (literate Bird-style Haskell)
 
* [http://www.ninebynine.org/Software/Swish-0.2.1/HaskellRDF/Dfa/Dfa.lhs Dfa.lhs], finite automata (literate Bird-style Haskell)
* [http://www.cse.unsw.edu.au/~dons/data/RedBlackTree.html RedBlackTree.hs], a red-black tree ([http://www.polyomino.f2s.com/david/haskell/hs/redblacktree.hs.txt raw])
+
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* [http://www.polyomino.f2s.com/david/haskell/hs/RedBlackTree.hs.txt RedBlackTree.hs], a red-black tree
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<!--
 
* [http://www.cse.unsw.edu.au/~dons/data/Prime.html Prime.hs], prime numbers ([http://andrew.bromage.org/darcs/numbertheory/Math/Prime.hs raw])
 
* [http://www.cse.unsw.edu.au/~dons/data/Prime.html Prime.hs], prime numbers ([http://andrew.bromage.org/darcs/numbertheory/Math/Prime.hs raw])
* [http://www.cse.unsw.edu.au/~dons/data/Foldable.html Foldable.hs], traversable data structures ([http://darcs.haskell.org/packages/base/Data/Foldable.hs raw])
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-->
* [http://www.cse.unsw.edu.au/~dons/data/ByteString.html ByteString.hs], high-performance string type ([http://darcs.haskell.org/packages/base/Data/ByteString.hs raw])
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* [http://darcs.haskell.org/packages/ndp/Data/Array/Parallel/Stream/Flat/Combinators.hs Combinators.hs], array combinators
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* [http://hackage.haskell.org/packages/archive/base/latest/doc/html/src/Data-Foldable.html Foldable.hs], traversable data structures ([http://hackage.haskell.org/packages/archive/base/latest/doc/html/Data-Foldable.html docs])
* [http://www.cse.unsw.edu.au/~dons/data/SmallCheck.html SmallCheck.hs], a testing framework ([http://www.cse.unsw.edu.au/~dons/code/lambdabot/scripts/SmallCheck.hs raw])
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* [http://haskell.org/haskellwiki/Darcs_repositories More code ...]
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* [http://www.haskell.org/ghc/docs/latest/html/libraries/bytestring/src/Data-ByteString.html ByteString.hs], high-performance string type ([http://code.haskell.org/bytestring/Data/ByteString.hs raw], [http://hackage.haskell.org/package/bytestring docs])
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* [https://github.com/feuerbach/smallcheck/blob/master/Test/SmallCheck.hs SmallCheck.hs], a testing framework ([https://raw.github.com/feuerbach/smallcheck/master/Test/SmallCheck.hs raw], [http://hackage.haskell.org/package/smallcheck docs])
  +
  +
* [http://www.haskell.org/haskellwiki/Darcs_repositories More code ...]
   
 
=== Application code ===
 
=== Application code ===
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monadic IO, and sometimes other advanced features such as concurrency:
 
monadic IO, and sometimes other advanced features such as concurrency:
   
* [http://www.abridgegame.org/repos/darcs-unstable/PatchCommute.lhs Darcs], a revision control system (uses literate latex Haskell style)
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<!--
* [http://svn.openfoundry.org/pugs/src/Pugs/Eval.hs Pugs], a perl6 implementation
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* [http://nanardon.zarb.org/darcs/darcs/PatchCommute.lhs Darcs], a revision control system (uses literate latex Haskell style) ([http://darcs.net home])
* [http://www.cse.unsw.edu.au/~dons/code/yi/Yi/Core.hs Yi], a text editor
+
-->
* [http://j.mongers.org/pub/haskell/darcs/conjure/Conjure/Torrent.hs Conjure], a bittorrent client
+
* [http://svn.openfoundry.org/pugs/src/Pugs/Eval.hs Pugs], a perl6 implementation ([http://pugscode.org home])
  +
  +
* [https://github.com/yi-editor/yi/blob/master/yi/src/library/Yi/Core.hs Yi], a text editor, ([http://www.haskell.org/haskellwiki/Yi home], [https://raw.github.com/yi-editor/yi/master/yi/src/library/Yi/Core.hs raw, [http://hackage.haskell.org/package/yi doc])
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<!--
 
* [http://darcs.haskell.org/~lemmih/downNova/src/Torrent.hs DownNova], a file downloading program
 
* [http://darcs.haskell.org/~lemmih/downNova/src/Torrent.hs DownNova], a file downloading program
* [http://www.cs.york.ac.uk/fp/darcs/cpphs/Language/Preprocessor/Cpphs/Tokenise.hs cpphs], an implementation of the C preprocessor
+
-->
* [http://darcs.haskell.org/ghc/compiler/simplCore/Simplify.lhs GHC], a Haskell compiler (literate latex style)
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* [http://www.augustsson.net/Darcs/Djinn/LJT.hs Djinn], a theorem prover
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* [http://www.cs.york.ac.uk/fp/darcs/cpphs/Language/Preprocessor/Cpphs/Tokenise.hs cpphs], an implementation of the C preprocessor ([http://www.cs.york.ac.uk/fp/cpphs/ home])
* [http://darcs.haskell.org/c2hs/c2hs/c/CTrav.hs c2hs], a C to Haskell interface generator
+
* [http://www.cse.unsw.edu.au/~dons/code/lambdabot/LBState.hs Lambdabot], an IRC bot
+
* [http://darcs.haskell.org/ghc/compiler/simplCore/Simplify.lhs GHC], a Haskell compiler (literate latex style) ([http://www.haskell.org/ghc/ home])
* [http://www.cse.unsw.edu.au/~dons/code/hmp3/Core.hs hmp3], an curses mp3 player
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* [http://haskell.org/haskellwiki/Darcs_repositories More code ...]
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* [http://darcs.augustsson.net/Darcs/Djinn/Djinn/LJT.hs Djinn], a theorem prover ([http://darcs.augustsson.net/Darcs/Djinn/ home])
  +
  +
* [http://code.haskell.org/c2hs/src/C2HS/C/Trav.hs c2hs], a C to Haskell interface generator ([http://www.cse.unsw.edu.au/~chak/haskell/c2hs/ home])
  +
  +
* [http://code.haskell.org/lambdabot/LBState.hs Lambdabot], an IRC bot ([http://www.haskell.org/haskellwiki/Lambdabot home])
  +
  +
* [http://code.haskell.org/~dons/code/hmp3/Core.hs hmp3], a curses mp3 player
  +
  +
* [http://www.haskell.org/haskellwiki/Darcs_repositories More code ...]
   
=== Wiki examples===
+
== Examples ==
   
Here is a list of other random code collected on this wiki, replacing
+
; [[Tying the Knot]] : An example that illustrates different ways to define recursive data structures. The example defines a simple language (illustrating how to define some recursive structures) and an interpreter for the language (illustrating how to work with the recursive structures).
[http://haskell.org/hawiki/CodeOnTheWiki CodeOnTheWiki]. Contributors
 
of code to the old area are encouraged to bring their code over here.
 
This should only be done by the original author because anything on
 
these pages is automatically licensed under the Simple Permissive
 
License ([[HaskellWiki:Copyrights]]).
 
   
Most examples are roughly intermediate to advanced in difficulty.
+
; [http://members.chello.nl/hjgtuyl/tourdemonad.html A tour of the Haskell Monad functions]: Small usage examples of the basic Haskell monad functions
   
* [[Prelude extensions]]: Simple things you've always wished were in the Prelude.
+
[[Category:Code]]
* [[Gallery]]: Complete small programs.
 
* [[Blow_your_mind|Blow your mind]]: Short, useful, cool, magical examples, which should incite the reader's curiosity and (hopefully) lead him to a deeper understanding of advanced Haskell concepts.
 
* [[Sudoku]]: Solvers for popular puzzle [http://en.wikipedia.org/wiki/Sudoku Sudoku]
 
* [[NewMonads]]: Useful monads that are not in the main library.
 
* [[PrincipalVariationSearch]]: Principal variation search
 
* [http://haskell.org/hawiki/ShootoutEntry Shootout Entries]: Examples still on the old wiki for the [http://shootout.alioth.debian.org/index.php The Computer Language Shootout Benchmarks].
 
* [http://www.informatik.uni-bonn.de/~ralf/ Ralf Hinze] maintains a [http://www.informatik.uni-bonn.de/~ralf/software.html Haskell software page]
 

Latest revision as of 16:05, 26 February 2012

To get a feel for what real world Haskell looks like, here are some examples from various popular Haskell projects. To start learning the language, good places to start are Learning Haskell, Haskell in 5 steps, and Books and tutorials.

More code may be found on the wiki.


[edit] 1 Library code

Library code usually differs from application code: it is often highly structured, and documented with haddock, and can be rather optimised. Some instructive examples (syntax highlighting by hscolour):

  • Unix.hs, simple unix tools, for beginner Haskellers
  • Dfa.lhs, finite automata (literate Bird-style Haskell)

[edit] 2 Application code

Code from popular Haskell applications. Such code often makes use of a monadic IO, and sometimes other advanced features such as concurrency:

  • cpphs, an implementation of the C preprocessor (home)
  • GHC, a Haskell compiler (literate latex style) (home)
  • c2hs, a C to Haskell interface generator (home)
  • hmp3, a curses mp3 player

[edit] 3 Examples

Tying the Knot 
An example that illustrates different ways to define recursive data structures. The example defines a simple language (illustrating how to define some recursive structures) and an interpreter for the language (illustrating how to work with the recursive structures).
A tour of the Haskell Monad functions
Small usage examples of the basic Haskell monad functions