#8813: further support deriving instances Typeable1, Typeable2, etc ----------------------------------------------+---------------------------- Reporter: maeder | Owner: Type: task | Status: closed Priority: normal | Milestone: Component: Compiler | Version: Resolution: wontfix | 7.8.1-rc1 Operating System: Unknown/Multiple | Keywords: Type of failure: GHC rejects valid program | Architecture: Test Case: | Unknown/Multiple Blocking: | Difficulty: Unknown | Blocked By: | Related Tickets: ----------------------------------------------+---------------------------- Comment (by maeder): http://hackage.haskell.org/package/uni-graphs-2.2.1.0/docs/Graphs- GraphDisp.html contains an example where replacing Typeable1 by Typeable was not enough, because Typeable1 used to fix the kind. I had to add {{{ +{-# LANGUAGE KindSignatures #-} }}} and replace the empty class as follows: {{{ -class Typeable1 nodeType => NodeTypeClass nodeType +class Typeable (nodeType :: * -> *) => NodeTypeClass nodeType }}} So it would make sense to further supply Typeable1, Typeable2, etc. classes with matching kinds. Is there a way to circumvent the above "instances can only be derived" error? Is there a different way to supply TypeableN classes that imply/derive Typeable instances? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8813#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler