feat(stdlib): Vec type

[vezenovm]

Description

This PR utilizes the recent additions of mutable references and slices to create a Vec type.

Problem*

This is work towards resolving #1556

Summary*

I made a new type struct Vec<T> { slice: [T] } with a few builtin funcs that uses our slice builtins to implement a mutable vector type.

If a user wants to update a slice they no longer have to use this syntax:

    let mut slice: [Field] = [];
    for i in 0..5 {
        slice = slice.push_back(i);
    }
    assert(new_slice.len() == 5);

and can instead do this:

    let mut vector: Vec<Field> = Vec::new();
    for i in 0..5 {
        vector.push(i);
    }
    assert(vector.len() == 5);

as the builtin Vec functions use mutable references. The Vec type is essentially a mutable wrapper over slices.

Documentation

• This PR requires documentation updates when merged.

  • I will submit a noir-lang/docs PR.
  • I will request for and support Dev Rel's help in documenting this PR.

Additional Context

PR Checklist*

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[jfecher]

and can instead do this:

let mut vector: Vec<Field> = Vec::new();
for i in 0..5 {
    vector.push(i);
}
assert(vector.len() == 5);

The type annotation is not necessary here, right?

[vezenovm]

The type annotation is not necessary here, right?

Yeah it is unneeded I removed

[jfecher]

Looks good. Once we fix slices in if statements we can add functions like map as well.

[jfecher]

👍