Haskell (literate style) mode for Vim
   Syntax highlighting for literate Haskell scripts for the editor Vim by John Williams.
   http://www.haskell.org/libraries/lhs.vim

Haskell Mode for Eclipse
   Provides a Haskell Perspective, Haskell Document Types (Project, Module), a Syntax-Highlighting Editor, and ways to start GHC, Hugs and Haddock from within Eclipse.
   http://eclipsefp.sourceforge.net/haskell/

Haskell Mode for Emacs
   An Emacs mode currently supporting font locking, declaration scanning, documentation, indentation, hugs interaction.
   http://www.haskell.org/haskell-mode/

Haskell Mode for Nedit
   Nedit mode, implements syntax highlighting and macros for Haskell comments, by Koen Claessen.
   http://www.nedit.org/ftp/contrib/highlighting/haskell.pats

Haskell Mode for Vim
   Syntax highlighting mode for Vim, by John Williams.
   http://www.haskell.org/libraries/hs.vim

Hugs Mode for Emacs
   Provides fontification and cooperation with Hugs, by Chris Van Humbeeck.
   http://www.haskell.org/libraries/hugs-mode.el