module StackMachine where

import System.IO


type Transition state input output = (state, input) -> (state, output)

process :: Transition state input output -> state -> [input] -> [output]
process tr s [] = []
-- the definition of the function ``process'' is still incomplete!



-- You do not need to understand the details of the ``runprocess'' function

runprocess :: Transition state String String -> state -> IO ()
runprocess tr s = do
  hSetBuffering stdout LineBuffering  -- requires: ``import System.IO''
  interact (unlines . process tr s . lines)


-- uncomment the type signatures below as you define the functions!


-- countEcho :: Transition Integer String String


-- trAdd :: Transition Integer String String


-- polish :: Transition [Integer] String String