#12556: `stimes` adds extra power to Semigroup -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: task | Status: new Priority: normal | Milestone: Component: libraries/base | Version: 8.0.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect result | Unknown/Multiple at runtime | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Description changed by Iceland_jack: @@ -4,1 +4,1 @@ - }}} + New description: {{{ ghci> stimes 0 (undefined :: [_]) [] ghci> stimes 0 undefined () }}} makes it seem like `stimes 0` has some knowledge about `mempty` from `Monoid` but it has the following type {{{#!hs stimes 0 :: Semigroup a => a -> a }}} Desired behaviour? Given that type (assuming it only has the power of `<>`) I would have assumed this behaviour {{{ ghci> data L a = N | C a (L a) deriving Show ghci> instance Semigroup (L a) where (<>) = undefined ghci| ghci> stimes 0 (undefined :: L _) *** Exception: stimes: positive multiplier expected }}} -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12556#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler