Applications and libraries
The first place to look for data types or functions that do what you want is the Standard Prelude, then the Language and library specification (both parts of the Haskell standards documentation), then in whatever extra libraries are provided by the Haskell implementation you are using, then on the page you are looking at. If it is not here, then it may be in the archives of the Haskell Weekly News.
Search the standard libraries collection (by name or type signature) using Hoogle. A large collection of standard hierarchical libraries are currently distributed with GHC (from version 5.04), Hugs (from Nov 2003), and nhc98 (from 1.16).
Cabal, The Common Architecture for Building Applications and Libraries, is an framework for packaging, building, and installing any tool developed in the Haskell language. See also the Hackage database. There is a mailing list for discussing issues related to libraries.
Some of the libraries and tools linked to from the library and tools pages are proof-of-concepts rather than production code. Some have no longer been maintained for a long time. On freshmeat.net there is an alternative list of software written in Haskell. That list is currently short (for you to change that). Even more Haskell projects are documented in the community reports and in the archives of the Haskell Weekly News. Google knows about some rare things not documented anywhere else.
Categories of Libraries and Tools
- Program development
- Data structures
- Extended Haskell
- Tools for interfacing with other languages
- Operating systems and systems programming
- Concurrency and parallelism
- Database interfaces
- Graphical User Interface Libraries
- Web, HTML, XML
- Parsing, lexing and regular expressions
- Pretty-printer libraries
- Theorem provers
- Hardware verification
- Audio, music and sound
- Genetic programming
- Linguistics and natural language processing
- Cryptography and hashing
Project activity for some of the larger Haskell projects is graphed here.
Libraries for other languages
If you are thinking about designing a new library for Haskell, you ought to look what has been done in other languages. Here are standard library definitions for
Proposals for the module name space layout that can be used to guide the construction of new libraries.