ref: 7d146bd75d98bea509acfad35ee5515423892e47 dir: /tests/Bang.hs/
module Bang where (!) :: Int -> Int -> Int x ! y = x - y f :: Int -> Int f !x = x+1 main = do let !a = 1+2 print a print (2 ! 3) print (2! 3) print (2 !3) print (2!3) print (f 1)