Maybe
Overview
The Maybe type is a utility type that conveniently allows annotating optional types. It is equivalent to the union
between a type T and Void. The typical usage is with the voidish coalescing operator:
// A type/function pair that creates a closure that defaults optional values.
type Resolver = fn [T](value?: T) -> T;
let Resolver = fn [T](default: T): Resolver[T] {
return fn (value?) => value ?? default;
};