> Side effects and immutability are just the consequences of trying to create a primitive that can be used under function composition I think I see what you me

> Side effects and immutability are just the consequences of trying to create a primitive that can be used under function composition I think I see what you mean, but it sounds like you see function composition as the end, where I see it as a mean. To me, being side-effect free is the end because it helps me doing local reasoning which ultimately makes programs easier to reason about. That being said, I understand it may be easier to characterize formally FP using function composition.