functional programming - Iterate over all pair combinations without repetition in Haskell

Question

In haskell, given a list of elements, xs, the simplest way to iterate over all pair permutations with repetitions is:

[(x,y) | x <- xs, y <- xs]

I wish to be able to do the same, but only on combinations. If x and y were comparable, I could do

[(x,y) | x <- xs, y <- xs, x > y]

But I'd prefer a solution that is more generic and more efficient (I know that asympotitic complexity will remain squared, but we can halve actual runtime complexity by avoiding the usage of a filtering condition)

Answer 1

What about:

[ (x,y) | (x:rest) <- tails xs , y <- rest ]