Visual Haskell
Visual Haskell is a complete development environment for Haskell software,
based on Microsoft's Visual Studio platform. Visual Haskell integrates with
the Visual Studio editor to provide interactive features to aid Haskell
development, and it enables the construction of projects consisting of
multiple Haskell modules, using the Cabal building/packaging infrastructure.
Visual Haskell is a complete system in one download: it includes a full GHC
installation with libraries, and various tools including Haddock, Happy, and
Alex.
http://www.haskell.org/visualhaskell/
Yours truly, Serguey Zefirov (thesz AT mail DOT ru)