2009/4/25 Ian Lynagh <ig...@earth.li>: > Ooops, sorrry about that. > >> Thanks Max, I now understand the reasoning behind this change a bit >> better. However, I'm still not convinced that it is a good idea, > > All in my opinion: > > * The fact that you are even allowed to let/where-bind values with > unlifted type is surprising. Making it clearer that something odd is > going on is a good thing. If it were up to me I think I would disallow > them completely.
Where this really breaks down is in a not-entirely-hypothetical language extension where you are able to write functions that are polymorphic in the strictness of certain type variables, and unlift arbitrary lifted types by prefixing them with a bang. Then, should you be allowed to write the following? map f (x:xs) = y : map f xs where y = f x By your rules, we should not be allowed to, because "f x" may potentially return an unlifted computation that is eagerly evaluated and hence may diverge. IMHO this is far too restrictive. Cheers, Max _______________________________________________ Cvs-ghc mailing list Cvs-ghc@haskell.org http://www.haskell.org/mailman/listinfo/cvs-ghc
