| it works as expected. which is why I think that the type should be:
|
| f :: forall t. ((forall b. C t b) => t -> t)
|
| or, bringing the quantifiers to the front:
|
| f :: forall t. exists b. (C t b => t -> t)
My brain is too small to figure out the consequences of adding first-class
existentials to Haskell; nor of how to decide when to universally quantify and
when to existentially quantify; nor of what to do when calling a function like
f.
Oleg's recent message gives many other examples you might like to consider.
http://www.haskell.org/pipermail/haskell-cafe/2006-December/020538.html
| >Why not reject it right away as ambiguous?
|
| I thought the reason for that was simply that there are situations in
| which f can actually
| be called, and op be used, such as "f (0::Int)" with "instance C Int
| b"?
yes, that's right.
Simon
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