Javascript, The Bad Parts #2: no custom comparisons in `Set` 🙀
In Javascript, Set treats objects only by reference, not by value, requiring weird contortions to maintain unique sets of non-primitive values.
In every other modern language I've worked with, the standard library set allows custom comparisons. But not Javascript.
In Java / Kotlin, HashSet defers to an object's hashCode method, which can be overridden to control comparisons. With TreeSet it's even easier: just pass a Comparator of your own into the constructor.
Python's set will handle any hashable value, so overriding __hash__ and __eq__ should do the trick.
Rust's HashSet relies on the Eq, Hash, and PartialEq traits---conceptually somewhat similar to Python's approach, with Rust's trait implementations and Python's special methods being two ways to accomplish much the same thing.
But in Javascript, and by extension Typescript, the standard library provides no facility for useful sets of custom types.
