Rust
You can declare and initialise a mutable array in Rust like this
let mut xs : [u32; 8] = [1,2,3,4,5,6,7,8];
alternatively you could separate the initialisation like:
let mut xs : [u32; 8] ;
xs = [1,2,3,4,5,6,7,8];
I was surprised when I was not able to re-assign the array with an array of different size… when doing this:
let mut xs : [u32; 8] = [1,2,3,4,5,6,7,8];
xs = [2,4];
you get this error
error[E0308]: mismatched types
--> src/main.rs:34:10
|
34 | xs = [2,4];
| ^^^^^ expected an array with a fixed size of 8 elements, found one with 2 elements
|
= note: expected type `[u32; 8]`
found type `[u32; 2]`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0308`.
error[E0308]: mismatched types
arrays of differnt sizes are different types. I thought that was really interesting. It is documented
This limitation on the size N exists because Rust does not yet support code that is generic over the size of an array type. [Foo; 3] and [Bar; 3] are instances of same generic type [T; 3], but [Foo; 3] and [Foo; 5] are entirely different types. As a stopgap, trait implementations are statically generated up to size 32. (from source)
(BTW kudos to the Rust people for very nice error messages)
If one really wants to use a set lenght array you can still do
let mut xs : [u32; 8] = [1,2,3,4,5,6,7,8];
xs[0] = 2;
xs[1] = 4;