[Haskell-cafe] What features should an (fictitious) IDE for Haskell have?

[Gueven Bay]

Greetings,

Imagine that you can decide what functionality and features an
Integrated Development Environment for Haskell should get. You can
make this IDE with your wishlist similar in power as other IDEs for
Java for example.

Now list as many features as you can, what would make the life of a
Haskell developer as comfortable as possible!?

I am dying to know how this list of features at the end (of this
thread) will look like.