Function for using arbitrary digit systems to convert numbers to strings

arbase.lua

local function base (digit_list)
  local b = #digit_list
  if b == 0 then
    return function(number) return "" end
  elseif b == 1 then
    local mark = digit_list[1]
    return function(number)
      return string.rep(mark, number)
    end
  else
    return function(number)
      number=math.floor(number)
      
      if number == 0 then
        return digit_list[1]
      end
      
      local places={}
      local pow=0
      local digits=math.floor(math.log(number) / math.log(b))+1

      for pow=digits,1,-1 do
        places[#places+1] = digit_list[
          (number % b^pow
          -number % b^(pow-1))
            /b^(pow-1) + 1]
      end

      return table.concat(places)
    end
  end
end

local bbar = base{"|"}

local b2 = base{'0','1'}

local b10 = base{
  '0','1','2','3','4','5','6','7','8','9',
}

local bten = base{
  'zero','one','two','three','four','five','six','seven','eight','nine',
}

local b32 = base{
  '0','1','2','3','4','5','6','7','8','9',
  'A','B','C','D','E','F','G','H','J','K',
  'L','M','N','P','Q','R','S','T','U','V',
  'W','X'
}