Funny, given that a systems programmer would argue that the "FP dogma" has convinced you that "sets, lists and maps" are "plain data structures" with universall

Funny, given that a systems programmer would argue that the "FP dogma" has convinced you that "sets, lists and maps" are "plain data structures" with universally-applicable performance characteristics in terms of runtime and space. And you can't even use no-longer-relevant chunks of their memory as scratch!