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

On Mon, Apr 6, 2009 at 8:53 AM, Paul Keir wrote:

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

When I want a lighter syntax for pairs (when doing a long list of them, e.g.), I often define (&) :: a -> b -> (a,b) a & b = (a,b) and then you can indeed write print $ 1 & 2 (assuming you get precedence right). Alex