{-# LANGUAGE QuasiQuotes #-}
module AltParsing where

import Control.Applicative
import Text.RawString.QQ
import Text.Trifecta

type NumberOrString = Either Integer String

a :: String
a = "blah"
b :: String
b = "123"
c :: String
c = "123blah789"

eitherOr :: String
eitherOr = [r|
123
abc
456
def
|]

parseNos :: Parser NumberOrString
parseNos = do
    skipMany (oneOf "\n")
    v <- (Left <$> integer) <|> (Right <$> some letter)
    skipMany (oneOf "\n")
    return v

main :: IO ()
main = do
    let p f i = parseString f mempty i
    print $ p (some letter) a
    print $ p integer b
    print $ p parseNos a
    print $ p parseNos b
    print $ p (many parseNos) c
    print $ p (some parseNos) c
    print $ p (some parseNos) eitherOr