forth

function classify(str)
  if tonumber(str) == nil then
    return str
  else
    return tonumber(str)
  end
end

local stack = function()
  local t = {}
  t.stack = {}
  t.push = function(self, number) table.insert(self.stack, number, 1) end
  t.pop = function(self) return table.remove(self.stack, 1) end
  return t
end
  

function main()
  local mode = 0

  local func = ""
  local body = {}
  
  local stack = {}
  local plus = function()
    table.insert(stack, table.remove(stack) + table.remove(stack))
  end
  local dup = function()
    local a = table.remove(stack)
    table.insert(stack, a)
    table.insert(stack, a)
  end
  local drop = function() table.remove(stack) end
  local swap = function()
    local a = table.remove(stack)
    local b = table.remove(stack)
    table.insert(stack, a)
    table.insert(stack, b)
  end
  local env = { plus = plus, dup = dup, drop = drop, swap = swap}

  while (mode >= 0) do
    local currBuff = {}
    for str in read():gmatch("[^%s]+") do
      table.insert(currBuff, classify(str))
    end
    while #currBuff > 0 do
      local tok = table.remove(currBuff, 1)

      if tok == "exit" then mode = -1; break; end

      if mode == 0 then -- live execution
        if type(tok) == "number" then
          table.insert(stack, tok)
        else
          if tok == ":" then mode = 1 end -- entering compilation
          if tok == ";" then mode = -1 break end
          if tok == ".s" then
            for k, v in pairs(stack) do
              io.write(v, " ")
            end
            print("")
          end
          if tok == "." then
            if #stack == 0 then return -1 else
              print(table.remove(stack))
            end
          end
          if not (env[tok] == nil) then
            local body = env[tok]
              if type(body) == "table" then
              for i = #body, 1, -1 do
                table.insert(currBuff, 1, body[i])
              end
            elseif type(body) == "function" then
              body()
            end
          end
        end
      elseif mode == 1 then -- getting name
        func = tok
        mode = 2
      elseif mode == 2 then -- building 
        if tok == ";" then 
          env[func] = body
          func = ""
          body = {}
          mode = 0
        else table.insert(body, tok) end
      end
    end
    io.write(" ok\n")
  end
  return mode
end

main()