> I can construct the Either knowing only one of A and B - from the example, > Either.Le(42, false) must be implicitly convertible to Either(bool, _) with > the B left unspecified at the instantiation point - this is an important > feature!
Wait ... what? That looks like the kind of feature that saves a couple of key strokes for the end user while causing endless ongoing pain for type system designers and compiler writers.
