Allow indexing arrays by a range

[SleepingShell]

Problem

Enable indexing of arrays by ranges such as in Rust.

It would also be useful to assign with ranges.

Happy Case

let x = [1,2,3, 4];
assert(x[0..2] == [1,2]);
assert(x[1..3] == [2,3]);
assert(x[2..] == [3,4]);

Assignment:

let mut x = [1,2,3];
x[0..2] = [4,4,4];
assert(x == [4,4,4]);

Alternatives Considered

No response

Additional Context

No response

Would you like to submit a PR for this Issue?

No

Support Needs

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[Savio-Sou]

@jfecher any thoughts?

[jfecher]

It's possible to implement without introducing too many new features but it'd likely require a copy of each index rather than a view into them since arrays are immutable internally. So you could easily create slices this way but mutating those slices afterwards wouldn't affect the original array.