#15755: randomRIO panic on (GHC version 8.4.3 for x86_64-apple-darwin) -------------------------------------+------------------------------------- Reporter: cmal | Owner: (none) Type: bug | Status: infoneeded Priority: normal | Milestone: Component: Compiler | Version: 8.4.3 Resolution: | Keywords: randomRIO Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by khanage): I've also encountered this on macos 10.13. Here's the logs from a ghci session: {{{ λ> :set -package random package flags have changed, resetting and loading new packages... λ> import System.Random (randomRIO) λ> randomRIO (10, 100) ghc: panic! (the 'impossible' happened) (GHC version 8.4.4 for x86_64-apple-darwin): nameModule system $dShow_a12oz Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable pprPanic, called at compiler/basicTypes/Name.hs:241:3 in ghc:Name Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug λ> r <- randomRIO (10, 100) λ> r 46 }}} Maybe ghci has a problem with showing unbound values? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15755#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler