Hello everyone! Suppose I have: class C a where someA :: a f :: C a => a -> Int f a = let x = someA :: a in -- BUG!! 0 BUG as I understand I due to `:: a` - this is another `a`, not the same as in `f` singature. But seems that it's the same `a` if `f` is the "method" of some instance. And such bug does not happen if I return it, so my question is how to create such `x` of type `a` in the body of the `f`? How to use `a` anywhere in the body of `f`? Is it possible? I found a way if I change signature to `forall a. C a => a -> Int`. But there are another questions in the case: - as I know all such params are under "forall" in Haskell by-default. Seems it's not true? - in method body seems they are under "forall" but in simple functions - not? - i'm not sure what exactly does this "forall", IMHO it unbounds early bound type's variables (parameters) by typechecker, but how `a` can be bound in the just begining of signature (where it occurs first time) ?! As for me, looks that w/o "forall" all `a`, `b`, `c`, etc in the body of simple functions always are different types. But w/ "forall" Haskell typechecker makes something like (on type-level): let a = ANY-TYPE in ... here `a` can occur and will be bound to ANY-TYPE Where am I right and where am I wrong? :) === Best regards, Paul