#13380: raiseIO# result looks wrong -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.2.1 Component: Compiler | Version: 8.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Other | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by rwbarton): I think it's just a bit of imprecise wording. It's right that `raiseIO#` returns bottom after being applied to ''two'' arguments, as: {{{#!hs raiseIO# :: a -> State# RealWorld -> (# State# RealWorld, b #) }}} But the function in the example is strict in `y` only after being applied to a third argument, i.e., executed. You can try this: {{{#!hs import Control.Exception f :: Int -> Int -> IO Int f x y | x > 0 = throwIO StackOverflow | y > 0 = return 1 | otherwise = return 2 u :: Int u = -1 {-# NOINLINE u #-} main :: IO () main = f u undefined `seq` return () }}} and it's not optimized to bottom. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13380#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler