#10457: Revise/remove custom mapM implementation for lists -------------------------------------+------------------------------------- Reporter: dolio | Owner: Type: task | Status: new Priority: normal | Milestone: 7.10.2 Component: libraries/base | Version: 7.10.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: Phab:D924 -------------------------------------+------------------------------------- Comment (by simonpj): I'm a bit lost. The only change seems to be this: {{{ instance Traversable [] where instance Traversable [] where traverse f = List.foldr cons_f (pure []) where cons_f x ys = (:) <$> f x <*> ys mapM = Monad.mapM -- <========= DELETE THIS LINE }}} That means using the default method, `traverse`, rather than `mapM`. Why is that a big deal? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10457#comment:8 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler