operation.hs

module Main where
  import Text.ParserCombinators.Parsec
  runop :: Char -> Integer -> Integer -> Integer
  runop '+' n1 n2 = n1 + n2
  runop '-' n1 n2 = n1 - n2
  runop '*' n1 n2 = n1 * n2
  runop '^' n1 n2 = n1 ^ n2

  operation :: Parser Integer
  operation = do
	  n1 <- number
	  o <- operator
	  n2 <- number
	  return (runop o n1 n2)

  operator :: Parser Char
  operator = do
    o <- oneOf "+-*^"
    return (o)

  number :: Parser Integer
  number = do
	  n <- many (oneOf "0123456789")
	  return (read n)