Re: [Haskell-cafe] Constraints on <$> vs <$!>

Prelude Control.Applicative> let f <$!> x = (f $!) <$> x Prelude Control.Applicative> :t (<$!>) (<$!>) :: Functor f => (a -> b) -> f a -> f b

On 10 Aug 2015, at 23:30, Will Yager wrote:

What about

f <$!> x = (f $!) <$> x

?

--Will

On Aug 10, 2015, at 14:20, Christopher Allen wrote:

...

http://stackoverflow.com/questions/9423622/strict-fmap-using-only-functor-no... seems to cover it.

On Mon, Aug 10, 2015 at 4:17 PM, Alexey Egorov wrote: Hello haskellers,

I wonder why <$> and <$!> have different typeclass constraints?

(<$>) :: Functor f => (a -> b) -> f a -> f b (<$!>) :: Monad m => (a -> b) -> m a -> m b _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe

-- Chris Allen Currently working on http://haskellbook.com _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-cafe

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