[Haskell-cafe] Infix tuple comma query (,)

module Main where data (:%^&) a b = a :%^& b deriving (Show) main = do print $ 18 :%^& (Just 99) print $ (,) 9 10 print $ 9 , 10 The last line in the code above causes a compile error. Why does infix use of the comma (tuple constructor?) function fail without brackets? Thanks, Paul