class

Array

A fixed size container for any element type.

Overview

An Array is a container that holds many values inside. Nara Arrays have a fixed size, you create the array with a number of elements it can hold, and then it never grows nor shrinks. Indexes are zero-based.

If you want a resizable Array use ArrayList.

Creation

Arrays have a literal syntax. Here we create a String Array of 3 elements:

var names: Array[String] = ["John", "Ahmed", "Yuto"]

Output:

Compiler Stderr:

To create an array with a variable size use Array::new and pass a initial value or a generator function:

// Creating an array of 100 elements, all `0`
var numbers1 = Array::new(size: 100, init: 0)
// [0, 0, 0, 0, ...]

// Creating an array of 100 elements, but with custom elements
var numbers2 = Array::new_with_gen(size: 100, generator: #{ $0 ** 2 })
// [0, 1, 4, 9, ...]

Output:

Compiler Stderr:

Access elements

To access the elements of an array use square brackets:

var names = ["John", "Ahmed", "Yuto"]
print(names[2])  //: Yuto

Output:

Compiler Stderr:

This access panics the thread of execution when the index is invalid. For a safe alternative use Array.get(usize), which returns the value or null.

var names  = ["John", "Ahmed", "Yuto"]
var friend = names.get(3)
friend == null

Output:

Compiler Stderr:

Setting elements

Use square brackets to set the value in an array. When doing this, you cannot assign to an invalid index, otherwise the thread panics. You cannot use this syntax to grow the array.

var names = ["John", "Ahmed", "Yuto"]
names[0]  = "Sarah" // ok
names[3]  = "Bob"   //! panic, index out of bounds

Output:

Compiler Stderr:

Functions

fun copy(self) -> Array['E]

Creates a new array with shallow copies of all elements

fun empty(self) -> bool

Returns `true` if the array has no elements

fun new(size: u64, init: 'E) -> Array['E]

Creates a new array with `size` elements, and all values as `init`.

fun new_with_gen(size: u64, generator: fun(...) -> 'E) -> Array['E]

Creates a new array with `size` elements, and all values as `init`.

fun len(self) -> u64

Returns the size of this array

fun get(self, at: usize) -> ?'Element

Returns the element at position `at`, or `null` if the position is out of bounds

fun find(self, predicate: fun(...) -> bool) -> ?'Element

Returns the first element that satisfies `predicate`, or `null` if not found

fun foldl(self, init: 'A, reducer: fun('A, 'B) -> 'A) -> 'A

Accumulates all values of the array into a single value

fun to_lowercase(self) -> self

Clones the string as lowercase