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Some people sometimes complain about Rust being a very "complex" language, usually in the context of a new feature being added as if it were the straw that breaks the camel's back. I'd like to flip the argument around: What existing Rust feature would you *remove*?

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specialization. it encourages people to write way more complicated generic unsafe code which is really bad and seems to be a big source of bugs in std

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how is it that generic code creates the need for unsafe?

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one of the main usecases of specialization is to do optimizations like "oh this iterator can be trusted to report its size and so we can pre-reserve a buffer and do no capacity/bounds checks"

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If we had stable specialization, I think the actual main usecase would be containers and algorithms - something like this vector addition has a generic implementation but if we know it's an f32 we can call into this hand-optimized version. </dreams>

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you realize that "containers and algorithms" is literally the most dangerous and subtle unsafe code that you want people writing as little as possible right?

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I still want the experts that write them to have these tools available. And I've never wanted to have this kind of gatekeeping mentality around low-level code.. that stuff is what I love to write (if I look down my crate list 🙂)

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Conservative approach is absolutely necessary for code that is fundamental. And at the same time, I agree that having the option to specialize *your own code* is good as well. All about establishing trust: don't take unnecessary risk in widely used code.

3:16 PM · May 20, 2022Twitter Web App