If I ever develop a program language, the first action I will take is the clang approach and make it a library based architecture. That way, people can build tools for the language including IDE integration without having to reinvent the wheel.
[1]: https://github.com/nominolo/scion/
However, there is simply less drive to develop tooling like that for Haskell than there is for Java. Haskell is a much easier language to use given just a moderately intelligent text editor and a REPL than most others. Java, on the other hand, it verbose and annoying even with a very good IDE.
So Haskell can have good support, but since it isn't terribly necessary it isn't anything like a top priority.
http://www.infoworld.com/d/application-development/microsoft...