definition module Smurf

from StdOverloaded import class zero, class toString

from Data.Maybe import ::Maybe

:: Stm = Push String
       | Input | Output
       | Cat | Head | Tail | Quotify
       | Put | Get | Exec

:: Program :== [Stm]

:: Stack :== [String]
:: Store :== [(String, String)]

:: State = { stack :: Stack
           , store :: Store
           }

instance toString Stm

instance zero State
instance toString State

step :: !Program State !*File -> *(Maybe (!Program, State), *File)
run :: !Program State *File -> *(Maybe State, *File)