[chongli]

But even if that were granted for the sake of argument, it's not much of a win for Haskell. The ability to create pure functions is a feature of every language that has been invented during the lifetime of probably every person reading this post, and therefore not really a differentiating feature of Haskell.

I already dealt with this three posts above:

And no, it's not the case that Haskell is the only language which allows you to write pure functions. People who try to claim that are being silly and dishonest. Haskell's advantage is that its type system allows you to know at a glance whether or not a function is pure.

Nor is lack of ability to create impure functions a feature that can be claimed of Haskell, because that simply isn't true. Haskell's real differentiator in that department is just that you've got to jump through hoops to do it. And if your business rules are inherently impure, then it's not clear to me how a language that tries to ghettoize impurity makes them easier to implement.

That's only the case for beginners who don't understand monads and their associated libraries. For an experienced programmer, Haskell offers much more powerful and expressive (not to mention safe) means of combining effectful computations than typical imperative languages.