I applaud the effort, but this is far from complete. As far as I can tell, you can only do standalone expressions, to the exclusion of anything interesting.

    Type Haskell expressions in here.
    > let x = 10
    not an expression: `let x = 10'

I understand that mueval has this limitation too? It's more defensible in the irc context that "state" would be disallowed. Here, it's just crippling.

I don't need the mtl stuff, but being able to define a basic function would be nice!

http://codepad.org/ will run full programs for you ... I guess that'll continue to be my tool of choice for online Haskell prototyping.

Still, this project does seem promising.