Interestingly, we can still do these two in the compiler with a caveat:
tuple_map (f,g) (a,b) --> (f a, g b)
generic_map f (a,b) --> (f a, f b)
provided we don't get into a type recursion. The trick is to bind the
arguments first. The result type can't be known until after this
is
I did some more work and got this to go:
class Applicable[A,D,C] {
virtual fun myapply : A * D -> C;
}
instance[DH,DT,CH,CT] Applicable[ (DH -> CH) * (DT -> CT), DH * DT, CH * CT] {
fun myapply : ((DH->CH) * (DT->CT)) * (DH * DT) -> CH * CT =
| (?ah , ?at) , (?dh, ?dt) => ah dh, at dt
;
}
