Irrefutable pattern failed in ghc 7.4.1
Thanks for your attention! Gary (newbie)
class Show a => Show_Listable a where
show_list :: [a] -> IO()
instance Show_Listable a -> Show a where
show_list lst = do
print "gen list";
print lst
lst :: Int -> [Int]
lst i = [1,2,3]
main = do
show_list (lst 1)
Output:
$ ghc bull.hs -o bull
[1 of 1] Compiling Main ( bull.hs, bull.o )
ghc: panic! (the 'impossible' happened)
(GHC version 7.4.1 for x86_64-unknown-linux):
compiler/rename/RnSource.lhs:429:14-81: Irrefutable pattern failed for pattern Data.Maybe.Just (inst_tyvars,
_,
SrcLoc.L _ cls,
_)
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug