That does not sound like a good example. The two-argument form of `map` already returns a lazy sequence. Same for `filter`. I thought lazy sequences are already supposed to get rid of the performance problem of materializing the entire collection. So

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eduction 2 hours ago | parent [-]

Lazy sequences reduce the size of intermediate collections but they “chunk” - you get 32 items at a time, multiply that by however many transformations you have and obviously by the size of the items.

There are some additional inefficiencies in terms of context capturing at each lazy transformation point. The problem gets worse outside of a tidy immediate set of transformations like you’ll see in any example.

This article gives a good overview of the inefficiencies, search on “thunk” for tldr. https://clojure-goes-fast.com/blog/clojures-deadly-sin/ (I don’t agree with its near condemnation of the whole lazy pattern (laziness is quite useful - we can complain about it because we have it, it would suck if we didn’t).)

	▲	kccqzy an hour ago \| parent \| next [-]
		So what’s your coding style in Clojure? Do you eschew lazy sequences as much as possible and only use either non-lazy manipulation functions like mapv or transducers? I liked using lazy sequences because it’s more amenable to breaking larger functions into smaller ones and decreases coupling. One part of my program uses map, and a distant part of it uses filter on the result of the map. With transducers it seems like the way to do it is eductions, but I avoided it because each time it is used it reevaluates each item, so it’s sacrificing time for less space, which is not usually what I want. I should add that I almost always write my code with lazy sequences first because it’s intuitive. Then maybe one time out of five I re-read my code after it’s done and realize I could refactor it to use transduce. I don’t think I’ve ever used eduction at all.
	▲	eduction 2 hours ago \| parent \| prev [-]
		This, by the way, is why the lead example in the original linked post on clojure.org is very much like mine.