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