module Calc where

import Control.Monad.State
import MonParser

--
-- Calculator
--
expr :: Parser Int
addop :: Parser (Int -> Int -> Int)
expop :: Parser (Int -> Int -> Int)
factor :: Parser Int
term :: Parser Int

addop = (do char '+'; return (+)) `mplus` (do char '-'; return (-))
expop = do char '^'; return (^)
factor = nat `mplus` bracket (char '(') expr (char ')')
term = factor `chainr1` expop
expr = term `chainl1` addop