On Wed, Apr 25, 2012 at 8:19 AM, Tyson Whitehead <twhitehead at gmail.com> wrote: > Is there a technical reason this couldn't be done? The Haskell report only > says doing this is not part of haskell. It doesn't say why. I think the problem is incoherence, what if the same Map value got used with two different instances of Int? -- Johan