Re: [Haskell-cafe] Class constraints on associated types ...

On Fri, Jan 2, 2015 at 1:59 PM, aditya siram wrote:

Since I upgraded to 7.8 from 7.5 that instance declaration is no longer accepted is no longer accepted since it violates FD's.

There is a patch adding a -XDysfunctionalDependencies extension here https://phabricator.haskell.org/D69. It looks like it didn't make it into 7.10