im not a functional guru, but it seems like one nice plus that is not usually mentioned when people praise the funtional style (testable, threadsafe, parallelizable, easier to reason about) is that (and i could be getting this really wrong) it seems like things like maybe, and functors in general help solve dealing with 0, 1, or many of a thing- like when its done right, youve abstracted away ever considering about that. im sure that 0, 1 many headache has a name but i forget it.
Purely functional, or simply not having side-effects and using immutability? No need to go full-Haskell to benefit.
Seems almost too good to be true. Can anybody else share any similar successful "war stories"?