You're exceedingly lucky if the developers you work with these days are aware of the differences between shallow and deep copy, or how object references work.

You're exceedingly lucky if the developers you work with these days are aware of the differences between shallow and deep copy, or how object references work. This is where I make the case for having knowledge of asm/C/C++. The JavaScript developers that started on JavaScript or, maybe, Ruby have no clue what the hell is going on in the language they are working in. I see this all the time. From senior and lead developers, too. They have no mental model for how pointers work. Which means they have no concept of what an object is, on a memory-organization level. They aren't always aware of when mutation will occur, and they are entirely too reliant on operations that are inefficient. In Lisp, this would be the developer than uses CONS everywhere. There is no awareness of the allocations behind the mechanisms. There is premature optimization and then there is not driving into the damn pothole in the first place! One of these is F1 racing and the other is basic driving skills. I believe this may also explain why so many developers are so bad at using git. Git is entirely based on pointers. There is an elegance and simplicity to git that is lost on many people.