[Haskell-cafe] Implicit concatenation in list comprehensions

[Sittampalam, Ganesh]

Roel van Dijk wrote:
> On Mon, Jul 20, 2009 at 1:27 PM, Roel van
> Dijk<vandijk.roel at gmail.com> wrote: 
>> I think the tuple sections are a great idea! It also makes tuple
>> types and constructors more alike: 
>> 
>> x :: (,) String Double
>> x = (,) "Pi" 3.14159
> 
> I just realised this is already in GHC :-) But does you patch also
> add the equivalent for tuple type annotations? 
> 
> x :: (String, ) Double
> x = ("Pi", ) 3.14159
> 
> I am also wondering what the following would/should mean:
> 
>   (1, , ( , 2), ) 'a' 'b' 'c'

I would expect it to be a type error, since I think the following is the
only sane type the tuple can have (assuming numeric literals :: Int):

(1, , ( , 2), ) :: a -> b -> (Int, a, c -> (c, Int), b)

Ganesh

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