On Nov 6, 2007 12:03 PM, Thomas Schilling <[EMAIL PROTECTED]> wrote: > On Tue, 2007-11-06 at 09:18 -0500, Graham Fawcett wrote: > > Hi folks, > > Is there a way to declare a 'toString' function, such that > > toString x | <x is a String> = x > > toString x | <x's type is an instance of Show> = show x > I think the simpler solution (for your particular problem) is to tag > strings that should be printed as-is: > > newtype Literal = Literal String > instance Show Literal where show (Literal x) = x > lit :: String -> Literal > lit = Literal
I almost replied to ask, "doesn't that solve a different problem?" But I see that in practice, it leads to a similar result, and without type-system trickery. The type-system trickery is still devilishly interesting, though. ;-) Thanks, G _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
