You could also avoid all this ambiguity/type application stuff with: data AsTitle = AsTitle class Repr a b where repr :: a -> b -> Repr b instance Repr Int AsTitle where repr n _ = ... ... print (repr n AsTitle)
Yes, "moving" of type from the right-side (result) to the left-side (arguments) solves the problem, sure.
(Repr b can be an associated type if you want to support different representations)
You only add a constraint as follows: repr n :: forall b. (Repr b ~ Repr AsTitle, ReprC Int b) => Repr b Yes... So, `b` is unbound/free type param. But I can bind it with func. deps, yes?
How? If you you bind it with a functional dependency on "a", you can only have a single "b" for each "a".
I don't know... I wrote to David my idea - additional param on the left-side of func. dependency, but how/what param? === Best regards, Paul