[Haskell-cafe] flip1 through flip9, useful?

[Alexander Solla]

On Mon, Jan 13, 2014 at 10:57 PM, Tony Morris <tonymorris at gmail.com> wrote:

>  On 14/01/14 15:48, Christian Marie wrote:
>
> I have defined a bunch of functions like this:
>
> 	-- | Move the fourth argument to the first place
> 	rotate4 :: (a -> b -> c -> d -> e) -> (d -> a -> b -> c -> e)
>
> 	-- | Reverse four arguments
> 	flip4 :: (a -> b -> c -> d -> e) -> (d -> c -> b -> a -> e)
>
> I decided to upload this as a library to hackage, as I personally find it
> useful, especially for writing FFI bindings.
>
> It seems like I can't be the first to write a library like this though, am I
> missing something obvious? Is this useful or stupid? Does it exist already?
>
> Full definition here:
> https://github.com/christian-marie/flippers/blob/master/src/Control/Flippers.hs
>
>
>
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>
>  Why not generalise to any functor?
>
> let flip f a = fmap ($a) f
>

I don't see that operator as "flip-like", personally.  It might behave as
flip in the case of the function functor , but that intuition does not
carry over to things like

fmap ($a) [f, g, h] = [f a, g a, h a]

I'd call it "funder", personally.
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