map package:containers is:exact

Map a function over all values in the map.

map (++ "x") (fromList [(5,"a"), (3,"b")]) == fromList [(3, "bx"), (5, "ax")]

map f s is the set obtained by applying f to each element of s. It's worth noting that the size of the result may be smaller if, for some (x,y), x /= y && f x == f y

Map a function over all values in the map.

map (++ "x") (fromList [(5,"a"), (3,"b")]) == fromList [(3, "bx"), (5, "ax")]

map f s is the set obtained by applying f to each element of s. If f is monotonically non-decreasing, this function takes <math> time. It's worth noting that the size of the result may be smaller if, for some (x,y), x /= y && f x == f y