[nightski]

I don't think value of FP is that it solves the complexity of parallelism. Rather it is that once one has solved the problem (designed the algorithm), FP can help assure the solution is implemented correctly. This in and of itself is a large advantage.

[sitkack]

I use functional programming because I lack the mental ability to hold so much state in my head. A friend of mine is a badass at programming in C++ using threads. I don't and will not have the ability he does. So I use FP and my programs are correct and by being functional the options to speed up my code are also easily proved correct.

Being able to handle large amounts of complexity and being ok with it is not necessarily a good thing. If I could reason like a compiler I would probably just use a flat memory model and address each byte individually.