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Collections

lib/collections/ provides the core data structures.

TypeFileDescription
ArrayList<T>lib/collections/ArrayList.mtDynamic array.
LinkedList<T>lib/collections/LinkedList.mtDoubly linked list.
HashMap<K, V>lib/collections/HashMap.mtOpen-addressing hash map.
HashSet<T>lib/collections/HashSet.mtOpen-addressing hash set.
Stack<T>lib/collections/Stack.mtLIFO stack.
ArrayQueue<T>lib/collections/ArrayQueue.mtFIFO queue.

All collections implement the corresponding interfaces in lib/interfaces/ (List<T>, Map<K, V>, Set<T>, Queue<T>, Deque<T>) and Iterable<T>.

ArrayList<T>​

import * from "lib/collections/ArrayList.mt";

ArrayList<string> names = new ArrayList<string>();
names.add("Alice");
names.add("Bob");
names.add("Carol");

print(names.size());           // 3
print(names.get(1));           // Bob
print(names.contains("Carol")); // true

for (string n : names) {
    print(n);
}

Common methods: add, remove, get, set, size, contains, clear, forEach, iterator, stream.

HashMap<K, V>​

import * from "lib/collections/HashMap.mt";

HashMap<string, int> ages = new HashMap<string, int>();
ages.put("Alice", 30);
ages.put("Bob", 25);

print(ages.get("Alice"));        // 30
print(ages.containsKey("Bob"));  // true
print(ages.size());              // 2

for (string name : ages.keys()) {
    print($"{name}: {ages.get(name)}");
}

Methods: put, get, remove, containsKey, keys, values, entries, size, clear.

HashSet<T>​

import * from "lib/collections/HashSet.mt";

HashSet<int> seen = new HashSet<int>();
seen.add(1);
seen.add(1);
seen.add(2);
print(seen.size());  // 2 (duplicates ignored)

Methods: add, remove, contains, size, clear, iterator.

Stack<T> and ArrayQueue<T>​

import * from "lib/collections/Stack.mt";
import * from "lib/collections/ArrayQueue.mt";

Stack<int> s = new Stack<int>();
s.push(1); s.push(2);
print(s.pop());  // 2

ArrayQueue<string> q = new ArrayQueue<string>();
q.enqueue("first");
q.enqueue("second");
print(q.dequeue());  // first

Iterators and Streams​

Every collection exposes an iterator() method and a stream() method. See Stream API for chained operations.

See Also​