>
> one of my love examples - is a "quick" sort one-liner:
>
> qs() = ()
> qs(x:xs) = qs( a←xs | a<x ) || x || qs( a←xs | a >= x )
>

Here is quick sort in Ruby
def qsort(arr)
    return [] if arr.length <= 0
    x, *xs = arr
    qsort(xs.select{|y| y<=x}) + [x] + qsort(xs.select{|y| y>x})
end