Arrays and objects

Arrays and strings are 1-indexed. Objects use string keys unless a typed map declares another key type.

Arrays

string[] names = ["Ada", "Grace", "Lin"]

log names[1]
names[2] = "Hopper"
names.append("Margaret")

Negative positions count from the end. Position 0 is invalid and produces a compile error when the compiler can see it.

Common array methods include append, prepend, pop, shift, insert, delete, contains, index, map, filter, some, every, sort, sortBy, reverse, join, clone, min, max, sum, and len.

int[] values = [3, 1, 4]
int[] doubled = values.map((int value) int -> value * 2)
int[] ordered = doubled.sort()

Objects

object user = {
  id: "u1",
  profile: {
    name: "Ada"
  }
}

log user.profile.name
user["active"] = true

A missing property returns null. Useful object methods include getKeys, getValues, getEntries, contains, insert, delete, pick, and clone.

References and copies

Assigning an array, object, or class instance with = shares the same mutable value:

object first = {count: 0}
object second = first
second.count = 1

log first.count

This logs 1. Call .clone() for an independent deep copy:

object second = first.clone()

Structs behave differently. They are values, so assigning a struct copies it.

Merging and spreading

++ merges arrays and objects as well as concatenating strings:

object base = {name: "Ada", active: false}
object enabled = base ++ {active: true}
int[] all = [1, 2] ++ [3, 4]

Spread values inside literals or function calls:

int[] first = [1, 2]
int[] all = [...first, 3]
object copy = {...base, role: "owner"}
log max(...all)

Destructuring

array pair = ["Ada", "Grace"]
[string first, string second] = pair
{id, profile: details} = user

Use _ to discard a position. The source expression runs once.

Iteration

Use in for values and of for positions or keys:

for index, name in names (
  log index ++ ": " ++ name
)

for index of names (
  log index
)

Both indexes start at 1 for arrays and strings.