Collections

Arden provides built-in collection and iterator types as compiler-supported intrinsics.

List<T>

List<T> is a growable sequence.

Create one with:

xs: List<Integer> = List<Integer>();

Optional capacity:

xs: List<Integer> = List<Integer>(32);

That reserves backing storage, but the list still starts empty.

Common Methods

• push(value: T): None
• pop(): T
• get(index: Integer): T
• set(index: Integer, value: T): None
• length(): Integer

Example:

xs: List<Integer> = List<Integer>();
xs.push(10);
xs.push(20);
xs.set(0, 99);
println("{xs.get(0)}");

Map<K, V>

Map<K, V> is the built-in key/value collection type.

Create one with:

scores: Map<String, Integer> = Map<String, Integer>();

Common Methods

• insert(key: K, value: V): None
• get(key: K): V
• contains(key: K): Boolean
• length(): Integer

Example:

scores: Map<String, Integer> = Map<String, Integer>();
scores.insert("Alice", 100);

if (scores.contains("Alice")) {
    println("{scores.get("Alice")}");
}

Set<T>

Set<T> stores unique values.

Create one with:

seen: Set<Integer> = Set<Integer>();

Common runtime surface includes membership and mutation helpers such as:

• add(value: T): None
• contains(value: T): Boolean
• remove(value: T): Boolean

Use the corresponding example files to confirm current behavior when exploring the language.

Range<T>

Range<T> is the iterator type produced by range(...).

Examples:

r: Range<Integer> = range(0, 5);
r2: Range<Integer> = range(0, 10, 2);
rf: Range<Float> = range(0.0, 1.0, 0.25);

Rules:

• arguments must be either all Integer or all Float
• step must be non-zero

Common Methods

• has_next(): Boolean
• next(): T

Example:

mut total: Integer = 0;
r: Range<Integer> = range(1, 6);

while (r.has_next()) {
    total += r.next();
}

See also:

• Range Types