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John Carmack on mutable variables

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504 points azhenley | 1 comments | 31 Oct 25 02:34 UTC | HN request time: 0.206s | source
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stevage ◴[31 Oct 25 03:51 UTC] No.45768231[source]▶
In JavaScript, I really like const and have adopted this approach. There are some annoying situations where it doesn't work though, to do with scoping. Particularly:

- if (x) { const y = true } else { const y = false } // y doesn't exist after the block - try { const x = foo } catch (e) { } // x doesn't exist after the try block

replies(4): >>45768310 #>>45768515 #>>45768529 #>>45771225 #
1. keeda ◴[31 Oct 25 04:46 UTC] No.45768529[source]▶
Ditto. These days those are the only cases where I use "let" in JS. The thing I miss most from Kotlin is the ability to return values from blocks, e.g.

val result = if (condition) { val x = foo() y = bar(x) y + k // return of last expression is return value of block } else { baz() }

Or:

val q = try { a / b } catch (e: ArithmeticException) { println("Division by zero!") 0 // Returns 0 if an exception occurs }

Edit: ugh, can't get the formatting to work /facepalm.