#13893: Improved Help for Control.Concurrent and Control.Exception when "variable not in scope" -------------------------------------+------------------------------------- Reporter: vanto | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Poor/confusing Unknown/Multiple | error message Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The piece of code that bgamari wrote in {{{#13891}}} is interesting from the point of view of the error messages.\\ {{{ main = do putStrLn "forking" forkIO $ bracket (putStrLn "forked") (const $ putStrLn "finalize") (const $ putStrLn "hello" >> threadDelay 100000000) threadDelay 10000 putStrLn "done" }}} When the imports are not written GHC answers.\\ {{{ Prelude> :l testfork [1 of 1] Compiling Main ( testfork.hs, interpreted ) testfork.hs:6:5: error: Variable not in scope: forkIO :: t0 -> IO a0 testfork.hs:6:14: error: Variable not in scope: bracket :: IO () -> (b1 -> IO ()) -> (b0 -> IO b2) -> t0 testfork.hs:6:101: error: Variable not in scope: threadDelay :: Integer -> IO b2 testfork.hs:7:5: error: Variable not in scope: threadDelay :: Integer -> IO a1 Failed, modules loaded: none. Prelude> }}} It would be advisable to complete by:\\ {{{Perhaps you intended to import Control.Concurrent}}} for {{{forkIO}}} and {{{threadDelay}}}.\\ {{{Perhaps you intended to import Control.Exception}}} for {{{bracket}}}.\\ I hope you have a way to write it once for all the variables involved. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13893 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler