[Dr_Emann]

Expand does actually exist in the standard library, but it's a bit of a strange incantation...

    vec.splice(i..i, std::iter::repeat(0).take(length));

This replaces the values in range `i..i` (an empty range starting at i) with `length` copies of `0`.

[Measter]

That's not exactly the same. Splice returns an iterator, it doesn't modify the collection in place.

[Dr_Emann]

Yes it does exactly that. It returns an iterator over the removed items, but when that iterator is dropped, it modifies the collection. See https://play.rust-lang.org/?version=stable&mode=debug&editio...

[Measter]

Huh... I guess I should read the docs more carefully next time; I clearly misunderstood them.