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snoyberg / mono-traversable

Type classes for mapping, folding, and traversing monomorphic containers
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How about changing whenM to take m a? #123

Closed jeiea closed 7 years ago

jeiea commented 7 years ago

Currently all your preludes export whenM :: m Bool -> m () -> m () intactly from Control.Monad. If I use act :: IO a with whenM, then it would be whenM mpred (act >> return ()). It can be bypassed by changing the signature to m Bool -> m a -> m (). And I think when is also considerable. How do you think?

snoyberg commented 7 years ago

I prefer the current signature, as it avoids bugs of accidentally ignoring return values. This is a common debate on the haskell community.

On Thu, Feb 9, 2017, 8:56 PM jeiea notifications@github.com wrote:

Currently your all preludes export whenM :: m Bool -> m () -> m () intactly from Control.Monad. If I use act :: IO a with whenM, then it would be whenM mpred (act >> return ()). It can be bypassed by changing the signature to m Bool -> m a -> m (). And I think when is also considerable. How do you think?

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