Function to add to Data.List

[Niklas Haas]

On Sat, 05 Apr 2014 17:53:04 -0400, John Wiegley <johnw at fpcomplete.com> wrote:
> I heard a talk that mentioned this transform today at Hac NYC, and was
> surprised it wasn't already in Data.List:
> 
>     -- | Sort a list using a key on each element.  This implements the
>     --   decorate-sort-undecorate paradigm, also called a Schwarzian transform.
>     sortByKey :: Ord b => (a -> b) -> [a] -> [a]
>     sortByKey f = map snd . sortBy (comparing fst) . map (\x -> (f x, x))
> 
> I would like to propose adding it.
> 
> John
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This already exists in the form of

sortBy . comparing

or

sortBy (comparing f)