9 Feb
2005
9 Feb
'05
6:59 a.m.
On Wed, Feb 09, 2005 at 11:50:48AM -0000, Simon Marlow wrote:
On 08 February 2005 12:33, Thomas Jäger wrote:
First of all
-- Cale Gibbard comparing :: (Ord a) => (b -> a) -> b -> b -> Ordering comparing p x y = compare (p x) (p y) fits nicely with the ...By functions from Data.List.
sortBy (comparing fst)
is just too cute not to have. Any objections?
only that it's not clear where to put it. This is useful when the function is expensive: -- sortImage f = sortBy (comparing f) sortImage :: Ord b => (a -> b) -> [a] -> [a] sortImage f xs = map snd $ sortBy (comparing fst) [(f x, x) | x <- xs]