Shuffle a list in VimL

shuffle.vim

" Shuffles list in place.
function! Shuffle(list)
  " Fisher-Yates-Durstenfeld-Knuth
  let n = len(a:list)
  for i in range(0, n-2)
    let j = Random(0, n-i-1)
    let e = a:list[i]
    let a:list[i] = a:list[i+j]
    let a:list[i+j] = e
  endfor
  return a:list
endfunction

" Returns a pseudorandom integer i such that 0 <= i <= max
function! Random(min, max)
  if has('unix')
    let i = system('echo $RANDOM')  " 0 <= i <= 32767
  else
    let i = system('echo %RANDOM%')  " 0 <= i <= 32767
  endif
  return i * (a:max - a:min + 1) / 32768 + a:min
endfunction