Collections

Use Vector<T> for growable contiguous storage:

import std;

std.Vector<Int> values! = std.Vector<Int>();
values.append(10);
values.append(20);

for value in values {
    Int current = value$.get();
}

Iteration borrows elements; it does not copy or move them out of the collection. remove(index) preserves order, while swap_remove(index) is O(1) and may change order. pop() returns an optional value; remove_last() requires a non-empty vector.

Maps and Sets

std.collection.HashMap<Int, String> names! =
    std.collection.HashMap<Int, String>();
names.insert(1, "one");
names.insert(2, "two");

guard names.get(2) is .some(name) else { return 1; }
if (!name.starts_with("two")) { return 2; }

HashMap iteration yields (K&, V&); HashSet iteration yields K&. Iteration order is deliberately unspecified and may differ between maps or program runs. Sort explicitly when output must be stable.

The default maximum load is 80%. A constructor can choose another integer percentage from 1 through 99:

std.collection.HashSet<Int> compact! =
    std.collection.HashSet<Int>(load_percent = 70);