I don't understand this take at all. The borrow checker is automatic and works across all variables. Defer et al requires you remember to use it, and use it correctly. It takes more effort to use defer correctly whereas Rust's borrow checker works for you without needing to do much extra at all! What am I missing?
What you're missing is that Rust's borrowing rules are not the definition of memory safety. They are just one particular approach that works, but with tradeoffs.
Namely, in Rust it is undefined behavior for multiple mutable references to the same data to exist, ever. And it is also not enough for your program to not create multiple mut - the compiler also has to be able to prove that it can't.
That rule prevents memory corruption, but it outlaws many programs that break the rule yet actually are otherwise memory safe, and it also outlaws programs that follow the rule but wherein the compiler isn't smart enough to prove that the rule is being followed. That annoyance is the main thing people are talking about when they say they are "fighting the borrow checker" (when comparing Rust with languages like Odin/Zig/Jai).
> The borrow checker is automatic and works across all variables.
Not that I'm such a Rust hater, but this is also a simplification of the reality. The term "fighting the borrow checker" is these days a pretty normal saying, and it implies that the borrow checker may be automatic, but 90% of its work is telling you: no, try again. That is hardly "without needing to do much extra at all".
If your use case can be split into phases you can just allocate memory from an arena, copy out whatever needs to survive the phase at the end and free all the memory at once. That takes care of 90%+ of all allocations I ever need to do in my work.
For the rest you need more granular manual memory management, and defer is just a convenience in that case compared to C.
I can have graphs with pointers all over the place during the phase, I don't have to explain anything to a borrow checker, and it's safe as long as you are careful at the phase boundaries.
Note that I almost never have things that need to survive a phase boundary, so in practice the borrow checker is just a nuissance in my work.
There other use cases where this doesn't apply, so I'm not "anti borrow checker", but it's a tool, and I don't need it most of the time.
junon|10 months ago
wavemode|10 months ago
Namely, in Rust it is undefined behavior for multiple mutable references to the same data to exist, ever. And it is also not enough for your program to not create multiple mut - the compiler also has to be able to prove that it can't.
That rule prevents memory corruption, but it outlaws many programs that break the rule yet actually are otherwise memory safe, and it also outlaws programs that follow the rule but wherein the compiler isn't smart enough to prove that the rule is being followed. That annoyance is the main thing people are talking about when they say they are "fighting the borrow checker" (when comparing Rust with languages like Odin/Zig/Jai).
vouwfietsman|10 months ago
Not that I'm such a Rust hater, but this is also a simplification of the reality. The term "fighting the borrow checker" is these days a pretty normal saying, and it implies that the borrow checker may be automatic, but 90% of its work is telling you: no, try again. That is hardly "without needing to do much extra at all".
That's what you're missing.
francasso|10 months ago
For the rest you need more granular manual memory management, and defer is just a convenience in that case compared to C.
I can have graphs with pointers all over the place during the phase, I don't have to explain anything to a borrow checker, and it's safe as long as you are careful at the phase boundaries.
Note that I almost never have things that need to survive a phase boundary, so in practice the borrow checker is just a nuissance in my work.
There other use cases where this doesn't apply, so I'm not "anti borrow checker", but it's a tool, and I don't need it most of the time.