[Haskell-cafe] (liftM join .) . mapM
a.biurvOir4 at asuhan.com
Tue Dec 29 07:44:23 EST 2009
I'd write it as
foo f = join .<$> sequence . (f <$>)
(.<$>) :: (.<$>) :: Functor f => (a -> b) -> ((x -> f a) -> (x -> f b))
x .<$> y = (x <$>) . y
is part of my line-noise toolbox.
This join .* sequence family of functions is quite common.
Should really have a name for them.
Tony Morris-4 wrote:
> Can (liftM join .) . mapM be improved?
> (Monad m) => (a -> m [b]) -> [a] -> m [b]
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