Quick sort on vimscript

command! QsortDemo :call <SID>QsortDemo()

func! s:QsortDemo()
  let list = [5, 2, 8, 9, 4, 1, 10, 3, 6, 7]
  echo list
  call <SID>Qsort(list, 0, 9)
  echo list
endfunc

func! s:Partition(list, p, q)
  let x = a:list[a:p]
  let i = a:p
  let j = i + 1
  while j <= a:q
    if a:list[j] <= x
      let i = i + 1
      call <SID>Exchange(a:list, i, j)
    endif
    let j = j + 1
  endwhile
  call <SID>Exchange(a:list, a:p, i)
  return i
endfunc

func! s:Exchange(list, a, b)
  let tmp = a:list[a:a]
  let a:list[a:a] = a:list[a:b]
  let a:list[a:b] = tmp
endfunc

func! s:Qsort(list, p, r)
  if a:p < a:r
    let q = <SID>Partition(a:list, a:p, a:r)
    call <SID>Qsort(a:list, a:p, q - 1)
    call <SID>Qsort(a:list, q + 1, a:r)
  endif
endfunc

:QsortDemo
[5, 2, 8, 9, 4, 1, 10, 3, 6, 7]
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

Ok!