Type function under a forall type

[Stefan Holdermans]

Simon, Tom,

I hit this type-error message in GHC 7.0.3:

  Cannot deal with a type function under a forall type:
  forall e. El e u

Is there a fundamental reason why type functions under a forall type are a bad idea? Of is it just something that hasn't been implemented/thought about yet?

Cheers,

  Stefan