Simon Peyton-Jones wrote:
Of course -fallow-undecidable-instances still lifts all restrictions, and then all bets are off.
Is the behaviour of GHC with -fallow-undecidable-instances (and -fcontext-stack) well-understood and specifiable? It is a very useful option, as you can join (meet?) classes like this:
class P a class Q a class (P a,Q a) => PQ a instance (P a,Q a) => PQ a -- Ashley Yakeley _______________________________________________ Haskell-prime mailing list Haskell-prime@haskell.org http://haskell.org/mailman/listinfo/haskell-prime
