I would hope that most standard libraries are optimized to avoid this sort of waste as much as possible. In F#, for example, I know that the standard `map` and `fold` are implemented imperatively for maximum performance.

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xdavidliu 4 days ago | parent [-]

I don't know F#, but even if that were true, I'm guessing you need a list of the data in memory in the first place in order to fold or map over. That's still a disadvantage, since with tail recursion you don't, and thus it takes O(1) memory total.

	▲	munchler 4 days ago \| parent [-]
		I'd be interested to see a concrete example of what you're talking about. Use a language, data structure, and function signature of your choice. My claim is that in most cases, such a function can be implemented efficiently by chaining together standard higher-order functions (i.e. combinators), rather than by writing a custom tail recursive solution from scratch.