This sounds a little odd to me. What's the actual use-case here? A test
#9127: Don't warn about pattern-bindings of the form `let !_ = rhs` -------------------------------------+------------------------------------ Reporter: refold | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.8.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by refold): Replying to [comment:2 igloo]: that the parameter parser doesn't thrown an exception? The code looks like this: {{{ foo :: RequestBuilder foo = do rq <- rGet let !_ = rqPostParams rq ... rPut rq }}} where `RequestBuilder` is a state monad (`StateT ...`). So we're forcing some parts of the state before passing it along; `let !_ = rhs` is used as a nicer syntax for `seq`. IMO it's a valid idiom. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9127#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler