14 Jan
2013
14 Jan
'13
2:48 p.m.
Hello,
On Mon, Jan 14, 2013 at 8:14 PM, Andrea Vezzosi
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.
But isn't this already possible via GeneralizedNewtypeDeriving? -- () ascii ribbon campaign - against html e-mail /\ www.asciiribbon.org - against proprietary attachments