I'm trying to test some properties with quickcheck. If these tests fail, they will almost certainly fail by nontermination. I've been using the 'within' function to catch these nontermination cases. However, I was surprised to find that this doesn't always work. 'within' uses the 'timeout' function under the hood. Here is an example that demonstrates the problem:
import System.Timeout import Control.Exception works :: Int -> Int works x = sum $ cycle [x] doesntWork :: Int -> Int doesntWork x = last $ cycle [x] test1 = timeout 1 $ evaluate $ works 5 == 5 -- terminates test2 = timeout 1 $ evaluate $ doesntWork 5 == 5 -- never terminates test1 returns Nothing as expected, but test2 never terminates. Why? I thought timeout exceptions are supposed to always work with pure (non FFI) Haskell code. Is there any way I can work around this? I'm using ghc 6.12.2 Thanks, - Job
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