Data.List.Key

Variant of Data.List functions like Data.List.group, Data.List.sort where the comparison is performed on a key computed from the list elements. In principle these functions could be replaced by e.g. sortBy (compare on f), but f will be re-computed for every comparison. If the evaluation of f is expensive, our functions are better, since they buffer the results of f.

Documentation

nub :: Eq b => (a -> b) -> [a] -> [a]

sort :: Ord b => (a -> b) -> [a] -> [a]

minimum :: Ord b => (a -> b) -> [a] -> a

argmin

maximum :: Ord b => (a -> b) -> [a] -> a

argmax

group :: Eq b => (a -> b) -> [a] -> [[a]]

Divides a list into sublists such that the members in a sublist share the same key. It uses semantics of Data.List.HT.groupBy, not that of Data.List.groupBy.

merge :: Ord b => (a -> b) -> [a] -> [a] -> [a]