Re: Rust kernel policy

Martin Uecker
2025-02-24T18:03:46Z

Am Montag, dem 24.02.2025 um 02:08 -0700 schrieb Ventura Jack:
> On Sun, Feb 23, 2025 at 4:32 PM comex <comexk@gmail.com> wrote:
> >
> > > On Feb 22, 2025, at 3:42 PM, Piotr Masłowski <piotr@maslowski.xyz> wrote:
> > >
> > > I'm sure you already know this, but the idea of safety in Rust isn't
> > > just about making elementary language constructs safe. Rather, it is
> > > primarily about designing types and code in such a way one can't "use
> > > them wrong”.
> >
> > And importantly, it’s very hard to replicate this approach in C, even
> > in a hypothetical ‘C + borrow checker’, because C has no generic types.
> >

One can have generic types in C. Here is an example
for Option<T> (I called it "maybe"). I don't think
it is too bad (although still an experiment):

https://godbolt.org/z/YxnsY7Ted

(The example can also be be proven safe statically)

Here is an example for a vector type (with bounds
checking):

https://godbolt.org/z/7xPY6Wx1T

> > Not all abstractions need generics, but many do.
>
> True, a more expressive and complex language like Rust, C++, Swift,
> Haskell, etc. will typically have better facilities for creating good
> abstractions. That expressiveness has its trade-offs. I do think the
> costs of expressive and complex languages can very much be worth it
> for many different kinds of projects. A rule of thumb may be that a
> language that is expressive and complex, may allow writing programs
> that are simpler relative to if those programs were written in a
> simpler and less expressive language. But one should research and be
> aware that there are trade-offs for a language being expressive and
> complex. In a simplistic view, a language designer will try to
> maximize the benefits from expressiveness of a complex language, and
> try to minimize the costs of that expressiveness and complexity.
>
> Rust stands out due to its lifetimes and borrow checker, in addition
> to it being newer and having momentum.
>
> What are the trade-offs of a more complex language? One trade-off is
> that implementing a compiler for the language can be a larger and more
> difficult undertaking than if the language was simpler. As an example,
> to date, there is only one major Rust compiler, rustc, while gccrs is
> not yet ready. Another example is that it can be more difficult to
> ensure high quality of a compiler for a complex language than for a
> simpler language.

I also point out that the way Rust and C++ implement generics
using monomorphization has a substantial cost in terms of
compile time and code size.

Martin