ghci-only panic
{-# LANGUAGE TypeFamilies #-}
main = do
b <- a
return (+b) -- return b -- is the same
a = return undefined
x = ()
*Main> main
ghc: panic! (the 'impossible' happened)
(GHC version 8.10.3:
nameModule
system $dNum_a1LQ
Call stack:
CallStack (from HasCallStack):
callStackDoc, called at compiler/utils/Outputable.hs:1179:37 in ghc:Outputable
pprPanic, called at compiler/basicTypes/Name.hs:251:3 in ghc:Name
*Main> x
ghc: panic! (the 'impossible' happened)
(GHC version 8.10.3:
nameModule
system $dMonad_a20B
Call stack:
CallStack (from HasCallStack):
callStackDoc, called at compiler/utils/Outputable.hs:1179:37 in ghc:Outputable
pprPanic, called at compiler/basicTypes/Name.hs:251:3 in ghc:Name