But you can't do something like instance E a On Fri, Aug 28, 2015 at 9:27 AM, Johannes Waldmann < johannes.waldmann@htwk-leipzig.de> wrote:

Re: http://repetae.net/recent/out/classalias.html

Prelude> :set -XConstraintKinds Prelude> class C a; class D a; type E a = (C a, D a); instance E a => C (Maybe a)

https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/constraint-k...

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