Why is not this working?

[hirppa]

const test = currency(0); test.add(1);

console.log(test.value); // 0 instead of 1

[eXamadeus]

It's immutable.

const a = currency(0);
const b = a.add(1);

console.log(a.value); // 0
console.log(b.value); // 1

It's one of the main features: