Re: Function to add to Data.List

On 2014-04-05 at 23:53:04 +0200, John Wiegley 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.

+1 with a preference on naming it 'Data.List.sortOn' (and I retract my suggestion of using RULES) PS: Btw, I'd suggest making 'Schwarzian transform' in the docstring into a Haddock link: <http://en.wikipedia.org/wiki/Schwartzian_transform Schwartzian transform>