Proposal: Data.Functor.<.> for `fmap f2 . f1`

[Edward Kmett]

This operator is usually named .: or the like. It is a weaker form of
fmap.fmap.

I'm pretty strongly -1 on including it in base under the <.> name.

I'm less strongly -1 on some .: variant.

-Edward

On Sat, Sep 19, 2015 at 9:30 PM, Ömer Sinan Ağacan <omeragacan at gmail.com>
wrote:

> I don't know if "I find this very useful" is enough for adding a function
> to
> base, but here it goes:
>
>     infixl 4 <.>
>     (<.>) :: Functor f => (b -> c) -> (a -> f b) -> (a -> f c)
>     f1 <.> f2 = fmap f1 . f2
>     {-# INLINE (<.>) #-}
>
> I first defined this couple of months ago and I find myself looking for
> this
> function all the time now.
>
> One problem with this is that the name is used by widely used `filepath`
> library.
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