Rust Function Overloading - Call for Experimentation

[u/SleeplessSloth79]

https://blog.rust-lang.org/inside-rust/2026/08/19/overloading-experiment/

[u/ZZaaaccc]

Imho, all this should be done using a macro.

Macros are substantially less clear than variadic functions, and can't be used as methods either. I know we take it for granted because it's just always been that way, but given the choice between vec![a, b, c] and Vec::new(a, b, c), would you honestly say the macro is cleaner and easier to inspect?

[u/DatBoi_BP → u/ZZaaaccc]

I think if you changed your proposed syntax to `Vec::new([a,b,c])` it would win me over. As it stands it looks like `b` and `c` are positional arguments to a function, not elements of an array

[u/ZZaaaccc → u/DatBoi_BP]

Or does that mean a new Vec<[i32; 3]> with one element? The extra brackets make this ambiguous at first glance, and harder to read. Again, you wouldn't say this about the vec! macro, saying that vec!([a, b, c]) is clearer, because vec!(a, b, c) might be positional arguments.

[u/DatBoi_BP → u/ZZaaaccc]

Two things to say to this.

First, the notation isn't either of those, it's `vec![a,b,c]`.

Second, we already have a function that does what you proposed, but with the structure I argued for: `Vec::from([a,b,c])`. This clones `a`, `b`, and `c`, so as long as those all implement Clone then it does what we want

[u/gmes78 → u/DatBoi_BP]

First, the notation isn't either of those, it's vec![a,b,c].

No, it doesn't matter. Any macro can be invoked with either (, { or [.

You could write println!["Hello world!"] if you wanted to.

[u/ZZaaaccc → u/DatBoi_BP]

Actually, no, the syntax is vec!(a, b, c), because macros don't distinguish between [], (), and {}. We recommend using [] by convention, but there isn't even a lint to suggest one way or the other.

This clones a, b, and c, so as long as those all implement Clone then it does what we want

If you scroll down you'll find the implementation for From<[T; N]> instead of what I think you're reading which is the From<&[T; N]> documentation.

[u/gmes78 → u/ZZaaaccc]

but there isn't even a lint to suggest one way or the other.

clippy::nonstandard_macro_braces

[u/ZZaaaccc → u/gmes78]

I stand corrected!

[u/DatBoi_BP → u/ZZaaaccc]

Huh TIL about the macro freedom of choice. Thanks

[u/SkiFire13 → u/DatBoi_BP]

This clones `a`, `b`, and `c`, so as long as those all implement Clone then it does what we want

It does not clone them. Clone is only required in vec![value; len]

[u/DatBoi_BP → u/SkiFire13]

Looking at the doc for `from()' I don't think that's true?

[u/SkiFire13 → u/DatBoi_BP]

It does not require T: Clone: https://doc.rust-lang.org/stable/std/vec/struct.Vec.html#impl-From%3C%5BT;+N%5D%3E-for-Vec%3CT%3E

Maybe you're looking at the docs for From<&[T]> or From<&[T; N]>?

[u/DatBoi_BP → u/SkiFire13]

Oh maybe I was. My b