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

[Ryan Ingram]

The prefix notation for
> \a b c -> (a,b,c)
is (,,)

Without the parentheses, it's not immediately clear whether
> foo $ a,b
means
> foo (a,b)
or
> foo (\c -> (a,b,c))
or some other, bigger tuple size.

Anyways, it's just syntax :)

  -- ryan


On Mon, Apr 6, 2009 at 9:08 AM, Daniel Fischer <daniel.is.fischer at web.de> wrote:
> Am Montag 06 April 2009 17:53:24 schrieb Paul Keir:
>> 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?
>>
>
> Tuples are special baked-in syntax. The parentheses are part of the tuple
> constructor(s).
> It may be confusing you that you can use it prefix as well as "aroundfix".
>
>>
>>
>> Thanks,
>>
>> Paul
>
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