I am having hard time understanding this statement:

Haskell types lack constructors, so the user never expects to be
able to conjure up a value of an unknown type.

I am not sure how say in a Java language a constructor can "conjure up a value of an unknown type".

daryoush

On Wed, Oct 15, 2008 at 12:55 PM, Bulat Ziganshin <bulat.ziganshin@gmail.com> wrote:
Hello Daryoush,

Wednesday, October 15, 2008, 10:56:39 PM, you wrote:

> If you notice  java generics has all sort of gotchas (e.g.
> http://www.ibm.com/developerworks/java/library/j-jtp01255.html).  I

large prob;em of OOP languages with generics is interaction between
those two types of polymorhism. covariant/contravariant typing is one
example. since Haskell lacks OOP classes, it doesn't have such
pronblem at all. overall, speaking, pure languages (pure OOP, pure FP,
pure LP) is much simpler than ones trying to combine OOP, FP and
everything else together. There Is Only One Way To Do It In Haskell ;)


--
Best regards,
 Bulat                            mailto:Bulat.Ziganshin@gmail.com