#8747: GHC 7.4.1 ghc: panic! (the 'impossible' happened) ----------------------------------+------------------------------- Reporter: codygman | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 7.4.1 Keywords: | Operating System: Linux Architecture: x86_64 (amd64) | Type of failure: GHCi crash Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------------+------------------------------- I was just trying to create the records in the all about monads tutorial and after changing my code to: {{{ import Data.Maybe (Maybe(Nothing,Just)) data Gender = M | F data Sheep = Sheep (Gender) (Maybe Sheep) (Maybe Sheep) deriving (show) main = undefined }}} I got the following error: {{{ *Main> :r [1 of 1] Compiling Main ( Main.hs, interpreted ) ghc: panic! (the 'impossible' happened) (GHC version 7.4.1 for x86_64-unknown-linux): nameModule show{tv aD4} }}} Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug I've attached my entire ghci log for completeness sake. I'm using debian stable and kernel 3.11-0.bpo.2-amd64. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8747 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler