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.
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)
- RedBlackTree.hs, a red-black tree
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:
- Yi, a text editor, (home, raw, [http://hackage.haskell.org/package/yi doc)
- cpphs, an implementation of the C preprocessor (home)
- hmp3, a curses mp3 player
- 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