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From: | Stefan Monnier |
Subject: | Re: Easy to add with push but not to the end of a list |
Date: | Mon, 28 Nov 2022 17:24:46 -0500 |
User-agent: | Gnus/5.13 (Gnus v5.13) |
>> > That's because adding to the end of a Lisp list is >> > a bad idea. > The bad idea comment disregards necessity. Another way to look at it is that you disregard the possibility to change your necessity. > Suppose I am accumulating indicators that are done at increasing value > of time and want to introduce them into another list in the order they > were encountered. What should one handle these things? Add them in the reverse order and finish with a simple `reverse`. That's a very standard design pattern with singly-linked lists (and in many/most cases the final `reverse` can be an `nreverse`). Of course, in practice I'm sure there are many other options if you consider the problem in context where you can make changes to other parts of your code (e.g. to use something else than a list). Stefan
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