Is FPH implemented in GHC?

[Simon Peyton-Jones]

| Some of the trivial functions, I mentioned above, have rank 2 types, some have
| impredicative types.  The latter ones typically have types of the form
|
|     f (forall t. signal t a) -> f (forall t. signal' t a')
|
| where f is some specific functor.

Aha -- that's impredicative all right. Good thanks.

| And as far as I understood, FPH brings advantages for both rank n and
| impredicativity.  Am I wrong at this point?

No, you're right.


Simon