#12160: MonadFail instance for (Either String)? -------------------------------------+------------------------------------- Reporter: lexi.lambda | Owner: Type: feature request | Status: new Priority: normal | Milestone: Component: libraries | Version: 8.0.1 (other) | Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by lexi.lambda): Your point about just using `IsString` makes sense to me, so maybe that would be better, instead. One of the reasons `MonadFail` might sometimes be desirable over `MonadError` is that `MonadError` does not make it possible to make a single expression generic over both `Either` ''and'' `IO`, unless the `Either` type is `Either IOException a`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12160#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler