[Haskell] Perhaps a bug in GHC 6.10
kr.angelov at gmail.com
Wed Dec 3 08:45:01 EST 2008
One of my students wrote code like this:
prop_blank s (i,j) li =
do if something then True else False
prop_blank (...) (i,j) (li+1)
This code is not accepted from GHC 6.8.3 because Bool is not a monad.
In particular the error message is:
Couldn't match expected type `Bool' against inferred type `a b'
In the expression:
Surprisingly the same code is accepted from GHC 6.10. This looks like
a bug for me. The easiest way to reproduce this is to try to evaluate:
> do True
in GHCi with GHC 6.8.3 and with GHC 6.10
Is there any reason to accept this code?
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