Tuples ([A, B, ...])

A Tuple is a fixed-length set of items of the given types. Example:

type Point = [number, number]
interface Math extends HybridObject {
  distance(a: Point, b: Point): number
}

Tuples can also have different types per value:

Bad ❌

type Values = (number | string | Person)[]
interface Math extends HybridObject {
  calculate(values: Values): void
}

The type in the Bad ❌ example generates an array of variants, where it's size is unknown and each value could be a number, a string or a Person. It is less efficient than a tuple because of the variant allocation.

Good ✅

type Values = [number, string, Person]
interface Math extends HybridObject {
  calculate(values: Values): void
}

The type in the Good ✅ example generates a tuple, where it's size is guaranteed to be 3 and each value is known at compile-time: values[0]: number, values[1]: string, values[2]: Person.