Haskell

Haskell is a purely-functional programming language.

Compiler and interpreter

 * The probably most important and up-to-date Haskell-implementation is the Glasgow Haskell Compiler (GHC). You can install it with . GHC also includes an interpreter called GHCI.
 * Furthermore, there's Hugs, an (meanwhile (almost) out-dated) interpreter for Haskell98. You can install it with.

Cabal
With cabal you can package and build libraries and programs. Install it with.

HLint
HLint checks and simplifies your haskell source code! Install it with.

Haskell-Mode for Emacs
The Haskell-Mode for (X)Emacs makes programming easier; install it with Then, you can configure it with.
 * for GNU Emacs, or with
 * > for XEmacs.

Haskell-Mode for Vim
There's also a Haskell-Mode for Vim.