A few things come to mind:
Sublime Text with Haskell plugins
SublimeHaskell: On Linux, I had difficulty making it work because of its dependencies, mainly because of ghc-mod, IIRC. It also made Sublime quite sluggish to respond, so it is disabled currently.
VIM with plugins
haskell-vim-now -- I've tried this, and it sets up a very nice Vim environment with ...