On Sun, Apr 22, 2012 at 10:37 AM, Brent Yorgey <byor...@seas.upenn.edu> wrote: > I do not think this is a bug. Since type classes are open, GHC does > not do any reasoning of the form "X is the only instance in scope, so > I will pick that one". Other instances could be added at any time > (perhaps in other modules). In this particular instance, GHC has no > reason to choose the Text instance other than the fact that it is the > only instance in scope -- that is, type inference is not enough to > determine that the Text instance should be chosen. > > However, I do agree that it would be nice to have a mechanism for > specifying default instances for arbitrary (user-defined) type > classes.
Couldn't we make a special case for IsString, like we do for Num, given it's special syntactic association with OverloadedStrings? -- Johan _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users