Maybe monad in TypeScript

maybe.ts

class Maybe<T> {
  constructor(private val: T) { }
  with<Z>(f: (z: T) => Z): Maybe<Z> {
    return new Maybe(this.return(f));
  }
  return<Z>(f: (z: T) => Z): Z {
    try {
      return (f(this.val));
    } catch (err) {
      return undefined;
    }
  }
}
const obj = { a: { b: { c: 123 } } };
const v = new Maybe(obj)
  .with(x => x.a.z)
  .with(x => x.b.h)
  .return(x => x.c.g);