On Fri, Mar 16, 2012 at 9:23 AM, Christopher Svanefalk
Are there any problems which cannot be solved a side effect-free language (such as Haskell)? In other words, are there problems that would explicitly demand semantics that can only be provided by a language allowing direct modification of external state variables, such as Java and C++?
Haskell, Java, C++ and most other languages out there are Turing-complete. That means that all of them are able to compute the same things. Assuming that the Church-Turing hypothesis is true, all algorithms may be coded in all of them.
If not, are there problems which are simply infeasible to solve with a side effect-free language?
If you're asking about performance, as in "is there a problem that can be solved in O(f(n)) time in Java but not in Haskell-sans-IO-and-ST?", then it becomes a harder question. I'm not sure what the answer is. Cheers, -- Felipe.