GHC 6.12.1 and impredicative polymorphism

Simon Peyton-Jones simonpj at
Mon Nov 2 04:32:24 EST 2009

| Is there any difference between "-XImpredicativePolymorphism" and "-
| XImpredicativeTypes"?

No there isn't.  There's only one flag, -XImpredicativeTypes.

| Hyena uses the latter, and we're using Hyena somewhat "in anger".

Interesting.  I hope you can get along without it, perhaps with a bit more newtype wrapping/unwrapping code.  As I say, the current situation is not good.


More information about the Glasgow-haskell-users mailing list