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Comment by kenjackson | Hacker News Reader

Don’t C/C++ scale linearly with more cores because you just compile different compilands on the cores? Wouldn’t that be the same for Swift? Note, I’ve never used Swift.

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Nope it doesn't work that way for swift, stuff has to repeat on multiple cores per file within a single module, leading to being less compute efficient the more cores you add, unless you force everything into a single thread with WMO mode, but then you have manually manage your build graph very carefully to stay compute efficient. It could've changed since I've last looked, but there are still things like that are lurking around.

https://github.com/apple/swift/blob/main/docs/CompilerPerfor...

But the same also applies to C++. A boatload of my compile time is spent on expanding, parsing the same header files again and again in different compilation units. This can be solved by precompiled headers, yeah. But then again a boatload of the compile time is spent on instantiating the same templates in different compilation units again and again and again.

It's just that the fact that the language is cursed from the beginning gives an illusion of "linear scaling".

Not if extern templates are used, at least for the common types.

Swift has this weird thing where a two files next to each other can use the symbols from their neighbors without any import. I find this... disturbing.

I think that is fine if language also does directory = namespace

It does not in swift's case. You have to set the namespace/module/library manually with the set of files and they never really embraced public submodules that might've reduced this.

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