#15489: TestCoercion should be a superclass of TestEquality -------------------------------------+------------------------------------- Reporter: Zemyla | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.4.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Given that you can implement {{{#!hs testCoercionFromEquality :: TestEquality f => f a -> f b -> Maybe (Coercion a b) testCoercionFromEquality fa fb = fmap repr $ testEquality fa fb }}} that shows the superclass relationship. Are there enough libraries that implement new instances of `TestEquality` that adding this superclass would break? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15489 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler