one of the insights of actual functional programming, which imperative programmers who "take the ideas of functional programming" never seem to understand
is that chaining maps and filters and so on can and should be extremely fast
I’d argue you can take the ideas of functional programming without these implementations.
Make your system out of pure functions, and make their insides efficient imperative code.
This style of FP where we chain .map and .filter on collections is wasteful of resources.