Ah! Suddenly I understand the weird error messages I've been seeing.
Thanks much for the explanation. --Bart
On Sun, Sep 8, 2013 at 9:29 AM, Henning Thielemann
Am 06.09.2013 19:56, schrieb Bart Massey:
TypeFamilies are kind of heavy machinery here :-), but since it would be confined to the library and seems to solve the problem, I'd be in favor of doing as you suggest. We can conditionally compile if we are worried about non-GHC implementations, I think. Do other folks have an opinion? --Bart
The right solution would be to have (>>) :: m () -> m a -> m a.
With this type GHC could infer the return type from the fact that the result of printf is unused.
However, since it was chosen to be (>>) :: m b -> m a -> m a, we end up with follow-up hacks.
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