[Haskell-beginners] Type unions

[aditya siram]

'$' has the same effect as parens around whatever's after it so 'Left
$ A x' ==  'Left (A x)'. Since Haskell is left associative 'Left A x'
== '(Left A) x' which is wrong and gives me a compile error.

And yes it has the same effect as putStrLn $ "welcome".

-deech

On Wed, Dec 15, 2010 at 8:15 AM, Guofeng Zhang <guofengzh at gmail.com> wrote:
> What does "$" mean in Left $ A x. Why does not write it as "Left A x"?
> For putStrLn $ "welcome", is the "$" has the same meaning as that in Left $
> A x?
>
> On Wed, Dec 15, 2010 at 4:26 AM, Russ Abbott <russ.abbott at gmail.com> wrote:
>>
>> Isn't "Either" the same thing as AorB in
>>
>> data AorB = Aconstructor Int | Bconstructor Int
>>
>> I want two separate types A and B along with a third type which is their
>> Union. Is that not possible?
>> In my actual case, I have more than two types.  So I would like a way to
>> take the union of an arbitrarily number of types.
>>
>> data Union = A1 | A2 | ...
>>
>> where each of A1, A2, ... has its own data declaration.
>>
>> -- Russ
>>
>> On Tue, Dec 14, 2010 at 12:14 PM, Tobias Brandt
>> <tob.brandt at googlemail.com> wrote:
>>>
>>> data AorB = Aconstructor Int | Bconstructor Int
>>
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