[Haskell-cafe] Re: A GHC error message puzzle

[Jason Dagit]

On Thu, Aug 12, 2010 at 1:25 PM, Wei Hu <wei.hoo at gmail.com> wrote:

> Anyone care to explain why? I also tested a slightly changed program
> pasted below, and am very confused.
>
> > main = do
> >   -- This call doesn't terminate, why?
> >   print $ nonTermination "a"
> >   -- Comment the above line to test the rest of the code
> >   -- RTS detects the loop and bails out
> >   print $ process "abc"
> >   -- Comment the above line to test the rest of the code
> >   inp <- readFile "input"
> >   -- I'm guessing (process inp) throws an exception,
> >   -- and the handler closes all files, making a second close fail?
> >   writeFile "output" $ process inp
>
> > process :: String ->  String
> > process xs = blackhole where blackhole = tail blackhole
>
> > nonTermination :: String -> String
> > nonTermination _ = blackhole where blackhole = blackhole
>

If you compile the program to use the non-threaded RTS does the behavior
change?

Jason
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