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@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@googlemail.com> wrote:
data AorB = Aconstructor Int | Bconstructor Int


_______________________________________________
Beginners mailing list
Beginners@haskell.org
http://www.haskell.org/mailman/listinfo/beginners