[Haskell-cafe] Ambiguous reified dictionaries

[Martijn van Steenbergen]

Lennart Augustsson wrote:
> That program is incorrect, it contains two instances for Monoid Int,
> and the compiler should flag it as illegal.

Two simultaneous instances are okay as long as you don't use any of 
those instances, right? Just like two imported symbols with the same 
name are okay as long as you don't use them.

Martijn.