Arrays

An array is a data structure that holds a number of values allowing them to be accessed by their index.

var arr = [1, 2, 3];

+ Operator and Arrays

Two arrays can be concatenated with the + operator.

var arr1 = [1, 2, 3];
var arr2 = [4, 5, 6];
var arr3 = arr1 + arr2; // [1, 2, 3, 4, 5, 6]

## Index Access

A value in an array can be accessed using square bracket notation.

```ql
var arr = [1, 2, 3];
var first = arr[0]; // 1

Additionally, negative indices can be used to access elements starting at the end.

var arr = [1, 2, 3];
var last = arr[-1]; // 3

With either positive or negative indicies, out-of-bound numbers will return nil.

var arr = [1, 2, 3];
var out_of_bounds1 = arr[3]; // nil
var out_of_bounds2 = arr[-4]; // nil

nil Safe Index Access

If an array is possibly nil, the get method can be combined with optional chaining.

var maybe_arr = nil;
var maybe_first = maybe_arr?.get(0); // nil

Programatically Creating Arrays

It may not always be possible to declare an array as a literal. In those cases, the array_of function can be used to create an array of a specified length. When no factory function is specified, each element of the array will be equal to it’s index.

var big_array = array_of(1000);
var big_array_doubled = array_of(1000, (value) -> value * 2);