Text editor with emacs and vim emulation. Written and extensible in haskell.
The Haskell Tool Stack stack is a cross-platform program for developing Haskell projects. It is aimed at Haskellers both new and experienced.
A small statically typed compile-to-JS language with extensible records and type-safe blocks.
Haskell build system and commandline interface to Hackage
The PureScript compiler and libraries have plenty of open issues which can be tackled by Haskell beginners.