I use Haskell and Scala (and also doing some Scheme, Common Lisp, SML, OCaml, Erlang) all under Linux (Ubuntu).
All of the above languages (compilers and interpreters) can be installed quite easily (there are packages that can be installed using apt-get or another package management system).
Scala has a good integration with Eclipse and the Scala plugin(s) are actively developed. If you want to learn more, there is a course on Scala currently running at Coursera which explains how to use Scala on Windows, Linux, and Mac. Maybe you do not have all the features and integration of Visual Studio, but I have developed quite large projects in Eclipse and it works just fine.
For editing Haskell (and the other languages listed above) I use gvim which is OK for small projects. Probably youYou can use another editor as well(e.g. EMACS), provided it has syntax highlighting for Haskell. I do not know of any Haskell-IDEOtherwise, but maybe there exists one. Probably another good option is emacs but I have not explored this possibility yetyou can take a look at haskellwiki (thanks to Zach L for the suggestion).
For managing the source code (versioning) I use SVN through Eclipse for all these languages.