Collections

Import std.collections to use array extensions and collection types:

import std.collections;

Array Extensions

let values = [10, 20, 30];
let count = values.length();
let index = values.indexOf(20);
let copied = values.clone();
let range = values.clone(1, 3);

clone creates an independent array. slice creates a read-only Span<T> that shares the underlying array:

let view = values.slice(1, 3);
let first = view.get(0);
let dense = view.toArray();

All ranges use [start, end). An out-of-bounds index raises an exception.

List

List<T> is a growable ordered collection:

let names = List<string>();
names.add("Alice");
names.add("Bob");
names.insert(1, "Carol");

let first = names.get(0);
names.set(0, "Alicia");
names.remove(1);
let count = names.size();
let items = names.entries();

entries() returns a read-only array copy. List<T> supports for/in:

for let name in names {
  println(name);
}

Map

The key type must satisfy Hashable<K>. The standard string implementation is provided by std.text, so string keys normally require both modules:

import std.collections;
import std.text;

let scores = Map<string, int>();
scores.set("Alice", 90);
scores.set("Bob", 85);

if scores.has("Alice") {
  println("{0}", scores.get("Alice"));
}

scores.remove("Bob");
let count = scores.count();

entries() returns MapEntity<K, V>[]; the key and value are stored in item1 and item2, respectively.

Set

let tags = Set<string>();
tags.add("feng");
tags.add("language");

let contains = tags.has("feng");
tags.remove("language");
let all = tags.entries();

As with Map, the element type must satisfy Hashable<K>.