I sometimes come across a situation when I only want to provide a
_partial_ type annotation, perhaps because the full type has some
variable unified with some variable in some other type annotation, or
something. For instance:
f :: forall a. [a] - [a] - [a]
f x y = g x where
g [] = y
I actually have wanted a similar thing at times, the proposal I had in
mind was a bit less drastic, simply allow '_' in type signatures which
will unify with any arbitrary type. that way you can give any function
the type
f :: _ - _
or if you just want to resstrict part of the type you could say
