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

What your talking about is just run length encoding on sorted data: the free online book Real World Haskell has a great example of this. You will want to sort the list before you put it through the runLengthEncoder.