Hi again, Tillmann Rendel wrote:
{-# LANGUAGE TypeFamilies #-} module D (ok) where import A import Bdata D client = D client type family Label client type instance A.Label (D client) = D.Label client type instance B.Label (D client) = D.Label client ok :: client -> [D.Label client] ok client = [ A.z (D client), B.z (D client)]
Oh, and note that I do not need UndecidableInstances here, because I match against the explicit module identity D.
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