Re: Overlapping, undecidable, incoherent -- or worse?

Simon Peyton-Jones wrote:

As a trivial example, try

f a = a |= a

What type shall we infer for f? f :: (Bounded a, Enum a, SemiRing a) => a -> a or f :: (CSemiRing a) => a -> a

This has always confused me - GHC always seems to use the strongest possible conditions when inferring types (CSemiRing is stronger than PO because it implies it). Why isn't the type just f :: (PO a) => a -> a ? Isn't this the most straight-forward (and universal) typing, especially in the presence of overlapping/undecidable instances? -Stefan