#8470: "Fix" spurious Unused do-bind warnings -------------------------------------+------------------------------------ Reporter: 2piix | Owner: Type: feature request | Status: closed Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Resolution: worksforme | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by 2piix): Yes, now that I've looked closer, I'm noticing that the spurious warnings happen when I'm performing an Acid-State update. The full warning is: {{{ src/Yesod/Foundation.hs:476:16: Warning: A do-notation statement discarded a result of type EventResult AddUser. Suppress this warning by saying "_ <- lift (($) acidUpdate Brilliance.Query.AddUser (Brilliance.User.User ((^.) auth Brilliance.userId) f l))" }}} EventResult AddUser ''happens'' to be (), under a type family definition. That is, I have code of the form {{{ instance SomeClass AddUser type EventResult AddUser = () }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8470#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler