#10523: Add Monoid instance for IO -------------------------------------+------------------------------------- Reporter: Gabriel439 | Owner: Type: feature | Status: new request | Milestone: Priority: normal | Version: 7.10.1 Component: Compiler | Operating System: Unknown/Multiple Keywords: | Type of failure: None/Unknown Architecture: | Blocked By: Unknown/Multiple | Related Tickets: Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- This is to add the following `Monoid` instance for `IO`: {{{#!hs instance Monoid a => Monoid (IO a) where mempty = pure mempty mappend = liftA2 mappend }}} I originally proposed this instance on the libraries mailing list a while ago: https://mail.haskell.org/pipermail/libraries/2014-November/024310.html ... and the proposal was well-received so I would like to contribute the instance. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10523 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler