Functional programming beyond Haskell

We have all learned functional programming in Haskell, but there are more functional languages like Lisp, Scheme, ML, and Clean.

Why should we even bother to look further than Haskell?

- You want your programs to run faster.
- Monads drive you mad (what are they anyway? warm fuzzy things?).
- You need objects.
- You sometimes need a more powerful module system.