List

Lists are mutable in Andy C++.

let my_list = [1,2,3];

// Values inside a list can be changed
my_list[2] = 4;

// You can add elements to the end of a list
my_list.push(99);

// Remove and return the last element of the list
let element = my_list.pop();

Indexing

Lists, strings, and tuples also support negative indexes. Negative indexes count from the end.

let my_list = [1,2,3,4,5,6,7,8,9];
assert_eq(9, my_list[-1]);

Element accessors

Besides the [] operator, lists provide four element accessor functions. They differ on two axes: whether negative indexes are allowed, and what happens when the index is out of bounds.

let my_list = [10, 20, 30];

assert_eq(my_list.get(0), 10);
assert_eq(my_list.get?(9), None);   // in range for a usize, past the end
assert_eq(my_list.index(-1), 30);   // wraps like `[]`
assert_eq(my_list.index?(-9), None);

index behaves like the [] operator (wrap + error on out of bounds); index? is its non-throwing counterpart.

Slicing

Use ranges to slice lists. Ranges can be inclusive or exclusive. Negative indices count from the end of the list.

let my_list = [0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100]

// Exclusive range: 3 to 6 (does not include index 6)
assert_eq([30, 40, 50], my_list[3..6]);

// Inclusive range: 3 to 6 (includes index 6)
assert_eq([30, 40, 50, 60], my_list[3..=6]);

// Negative indices: Counting from the end of the list
assert_eq([80, 90], my_list[-3..-1]);

A range whose start lands after its end (for example my_list[6..3]) is out of bounds and raises an error rather than returning a reversed or empty slice. This holds for lists, strings, tuples and deques alike.

Operators