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John Carmack on mutable variables

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498 points azhenley | 1 comments | 31 Oct 25 02:34 UTC | HN request time: 0.209s | source
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EastLondonCoder ◴[31 Oct 25 09:30 UTC] No.45770007[source]▶
After a 2 year Clojure stint I find it very hard to explain the clarity that comes with immutability for programmers used to trigger effects with a mutation.

I think it may be one of those things you have to see in order to understand.

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ndr ◴[31 Oct 25 13:05 UTC] No.45771558[source]▶
Clojure also makes it very easy, it'd require too much discipline to do such a thing in Python. Even Carmack, who I think still does python mostly by himself instead of a team, is having issues there.
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MetaWhirledPeas ◴[31 Oct 25 18:08 UTC] No.45774914[source]▶
> it'd require too much discipline to do such a thing in Python

Is Python that different from JavaScript? Because it's easy in JavaScript. Just stop typing var and let, and start typing const. When that causes a problem, figure out how to deal with it. If all else fails: "Dear AI, how can I do this thing while continuing to use const? I can't figure it out."

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1. codethief ◴[31 Oct 25 18:34 UTC] No.45775194[source]▶
I agree that Python is not too different and in general I treat my Python variables as const. One thing, however, where I resort to mutating variables more often than I'd like is when building lists & dictionaries. Lambdas in Python have horrible DX (no multi-line, no type annotations, bad type checker support even in obvious cases), which is why the functional approach to build your list, using map() and filter() is much more cumbersome than in JS. As a result, whenever a list comprehension becomes too long, you end up building your list the old-fashioned way, using a for loop and the_list.append().