($>) is analogous to (*>) not by dropping the f in the first position, but the f in the second, as proposed. (*>) :: Applicative f => f a -> f b -> f b ($>) :: Functor f => f a -> b -> f b It is unfortunate that (*>) is not equivalent to (flip (<*)), but it is a special case where breaking the "flipped characters" convention is useful for the sake of Applicative's convention to gather effects from left to right. It is nice that ($>) adheres to the flipped characters convention as well as being analogous to (*>). -- Dan Burton On Sun, Dec 8, 2013 at 9:22 AM, Stijn van Drongelen <rhymoid@gmail.com>wrote:
Data.Functor has <$> and <$, but not $>, which should be a flipped version of <$, analogous to <*>, <*, and *> in Control.Applicative.
Whoa there, it's not at all analogous. Your wording is almost suggesting that <* is a flipped *>, but beyond that, they are uncomparable to begin with.
Applicative functors:
(<*>) :: Applicative f => f (a -> b) -> f a -> f b (<*) :: Applicative f => f a -> f b -> f a (*>) :: Applicative f => f a -> f b -> f b
Removing the `f` in the first position, you'd get an honest analogue for any functor:
(<$>) :: Functor f => (a -> b) -> f a -> f b (<$) :: Functor f => a -> f b -> f a ($>) :: Functor f => a -> f b -> f b
Here, I don't see how ($>) could be anything else than `const id`.
Or am I missing something here?
_______________________________________________ Libraries mailing list Libraries@haskell.org http://www.haskell.org/mailman/listinfo/libraries