As i understand it, the monomorphism restriction applies to "constrained
type variables", but c :: forall a. a, so it remains polymorphic and each of
its uses can be instantiated to a different type.
2007/12/25, Henning Thielemann
I thought I understand monomorphism restriction. But it seems, I don't. I have boilt down my problem to the following test. Don't try to make any sense of it, it is just the smallest code I could come up with.
test :: (Integral a, RealFrac a) => a test = let c = undefined in asTypeOf (round c) c
When compiling I get:
Compiling StorableInstance ( src/StorableInstance.hs, interpreted )
src/StorableInstance.hs:38:17: Warning: Defaulting the following constraint(s) to type `Double' `RealFrac a' arising from use of `round' at src/StorableInstance.hs:38:17-21 In the first argument of `asTypeOf', namely `(round c)' In the definition of `test1': test1 = let c = undefined in asTypeOf (round c) c _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe