Counting unique elements in a list

Question

Is there a straight-forward combination of standard higher-order functions to count the unique elements in a list?

For example the result for

[1, 1,          


        

Answer 1

The simplest thing would be to sort the items into order, use "group" to put them into sub-lists of equal elements, and then count the items in each sub-list.

map (\xs -> (head xs, length xs)) . group . sort