GHC -O2 and unsafePerformIO

[Simon Marlow]

Neil Mitchell wrote:
> Hi
> 
> Thanks to dcoutts, I have now come up with an answer. I don't
> understand why it works now, but not before. I do remember than
> browsing either Core or STG is not a fun thing to do...
> 
> p_System_IO_hGetChar h   = trace "i am here" $
>    unsafePerformIO  $ getCharIO h
> 
> 
> {-# NOINLINE getCharIO #-}
> getCharIO h = do
>    c <- getchar
>    print c
>    return $ if c == (-1) then 0 else chr_ c

This is clearly a misuse of unsafePerformIO (as I'm sure you're aware).  Just 
out of interest - what's the context?

Cheers,
	Simon