what about generics (equivalent to templates in C++), which allow compile time optimizations all the way down which may not possible if the implementation is hidden behind a void*?

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OptionOfT 12 hours ago | parent [-]

Unless you use `dyn`, all code is monomorphized, and that code on its own will get optimized.

This does come with code-bloat. So the Rust std sometimes exposes a generic function (which gets monomorphized), but internally passes it off to a non-generic function.

This to avoid that the underlying code gets monomorphized.

https://github.com/rust-lang/rust/blob/8c52f735abd1af9a73941...

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dwattttt 5 hours ago | parent [-]

> This does come with code-bloat. So the Rust std sometimes exposes a generic function (which gets monomorphized), but internally passes it off to a non-generic function.

There's no free lunch here. Reducing the amount of code that's monomorphised reduces the code emitted & improves compile times, but it reduces the scope of the code that's exposed to the input type, which reduces optimisation opportunities.

	▲	josephg 4 hours ago \| parent [-]
		Yes. But I like that rust gives you the option. In C, the only way to write a monomorphized hash table or array list involves horribly ugly macros that are difficult to write and debug. Rust does monomorphization by default, but you can also use &dyn trait for vtable-like behaviour if you prefer.