On Mon, Jan 14, 2013 at 11:14 AM, Andrea Vezzosi <sanzhi...@gmail.com> wrote: > Have you considered the effect on types like Data.Set that use the > uniqueness of typeclass instances to maintain invariants? e.g. even when we > have "newtype X = X Y" coercing "Set X" to "Set Y" can produce a tree with > the wrong shape for the Ord instance of Y.
I was just going to say that. Changing newtypes changes instances, which isn't safe in the general case. -- Johan _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
