fun.hs

module Main where

import System.IO

infixl 1 <<

class OStream os where
    mkOStream :: os -> IO Handle

class OStreamObject a where
    intoString :: a -> String

instance OStream Handle where
    mkOStream = pure

instance OStream a => OStream (IO a) where
    mkOStream ma = ma >>= mkOStream

instance OStreamObject Char where
    intoString ch = return ch

instance OStreamObject a => OStreamObject [a] where
    intoString xs = xs >>= intoString

instance OStreamObject Int where
    intoString i = shows i ""

cout :: Handle
cout = stdout

cerr :: Handle
cerr = stderr

endl :: Char
endl = '\n'

(<<) :: (OStream os, OStreamObject a) => os -> a -> IO Handle
os << x = do
    h <- mkOStream os
    hPutStr h (intoString x)
    return h

int :: Integral a => a -> Int
int = fromInteger . toInteger

main :: IO ()
main = do
    cout << "Hello world!" << endl
    cout << (int)1234 << ' ' << (int)5678 << endl
    return ()