An example of "sameness" in the context of immutability (> TS 3.4 needed @see https://devblogs.microsoft.com/typescript/announcing-typescript-3-4/#improvements-for-readonlyarray-and-readonly-tuples)

arePairsEqual.immutable.ts

type NumberPair = readonly [number, number];

const areNumbersEqual = (a: number, b: number) => a === b;

const areNumberPairsEqual = (a: NumberPair, b: NumberPair) =>
  areNumbersEqual(a[0], b[0]) && areNumbersEqual(a[1], b[1]);

const p1 = [1, 2] as const;
const p2 = [1, 2] as const;
const p3 = [1, 3] as const;

areNumberPairsEqual(p1, p2); // true
areNumberPairsEqual(p1, p3); // false