#8066: Compiler Panic When Using Instance Derivation With Singletons ---------------------------------------+----------------------------------- Reporter: tvynr | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time crash | Unknown/Multiple Test Case: | Difficulty: Unknown Blocking: | Blocked By: | Related Tickets: ---------------------------------------+----------------------------------- Comment (by tvynr): That looks great, thanks. :) And for anyone else who encounters this problem or is perhaps about as confused by the TypeLits stuff as I am, adding the following fixes the panic in GHC 7.6.1 (and leads to revealing mistakes in the anyVar function): {{{ instance SingE (Kind :: QualForm) QualForm where fromSing x = case x of UnqualifiedTVarS -> UnqualifiedTVar QualifiedTVarS -> QualifiedTVar }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8066#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler