Make luvit more helpful by suggesting possible corrections.

helpful.lua

local uv = require('uv')
local colorize = require('utils').colorize

uv = setmetatable(uv, {
  __index = function (table, wanted)
    local closest = math.huge
    local name = nil
    for key in pairs(table) do
      local distance = string.levenshtein(key, wanted)
      if distance < closest then
        closest = distance
        name = key
      end
    end
    print("Warning: " .. colorize("failure", "uv." .. wanted) .. " is nil, did you mean " .. colorize("success", "uv." .. name) .. "?")
  end
})

function string.levenshtein(str1, str2)
  local len1 = string.len(str1)
  local len2 = string.len(str2)
  local matrix = {}
  local cost = 0
  -- quick cut-offs to save time
  if (len1 == 0) then
    return len2
  elseif (len2 == 0) then
    return len1
  elseif (str1 == str2) then
    return 0
  end
    -- initialise the base matrix values
  for i = 0, len1, 1 do
    matrix[i] = {}
    matrix[i][0] = i
  end
  for j = 0, len2, 1 do
    matrix[0][j] = j
  end
    -- actual Levenshtein algorithm
  for i = 1, len1, 1 do
    for j = 1, len2, 1 do
      if (str1:byte(i) == str2:byte(j)) then
        cost = 0
      else
        cost = 1
      end
      matrix[i][j] = math.min(matrix[i-1][j] + 1, matrix[i][j-1] + 1, matrix[i-1][j-1] + cost)
    end
  end
  -- return the last value - this is the Levenshtein distance
  return matrix[len1][len2]
end