[simias]

steveklabnik is (of course) correct, but you also have to consider the performance cost of a dynamicaly sized slice versus a statically sized array.

A situation I've encountered several times already is implementing statically sized FIFOs. At the moment in Rust I can't implement a type "FIFO of depth N" where is a generic, static parameter. My only choices are implementing "FIFO of depth n" where n is provided dynamically at runtime (and implemented internally using something like a VecDeque) or a completely fixed depth FIFO type that I need to duplicate for every depth (FIFO32, FIFO16, FIFO10 etc...).

If you require very high performance a dynamically checked FIFO can incur a fairly large overhead when a well optimized static FIFO can implement most operations in a couple of opcodes at most.

[steveklabnik]

You maybe could write something like this:

  pub struct Fifo<T: AsMut<[u8]>> {

and then back it with an array. I learned this trick from whitequark.

(Though maybe if you want something other than a slice of bytes, this gets harder... I've used this trick for ringbuffers/mmio only, personally, so YMMV.)

That being said real const generics will make this way nicer, eventually.

[glandium]

There's also https://crates.io/crates/generic-array

[simias]

I wasn't aware of this trick, thank you for that. I guess if I have to implement another FIFO before const generics land I'll have an opportunity to try it out...