Levenshtein distance in moonscript

levenshtein.moon

import min from math

levenshtein = (a, b) ->
  c = {nil, nil, nil, nil, nil}
  p = {nil, nil, nil, nil, nil}
  for i=1,#a+1
    c[i]=i-1 -- Distance to ""
  for i=1,#b
    p,c = c,p
    c[1] = i -- Distance from ""
    for j=1,#a
      deletioncost = p[j+1]+1
      insertioncost = c[j]+1
      local substitutioncost
      if a\byte(j) == b\byte(i)
        substitutioncost = p[j]
      else
        substitutioncost = p[j] + 1
      c[j+1] = min(deletioncost, insertioncost, substitutioncost)
  c[#a+1]

{:levenshtein}