result i fallback?const Maybe = <T>(value: T | null | undefined) => ({
map: <U>(fn: (val: T) => U) =>
value != null ? Maybe(fn(value)) : Maybe<U>(null),
getOrElse: (defaultVal: T) =>
value != null ? value : defaultVal,
});
const result = Maybe("hello")
.map(s => s.toUpperCase())
.map(s => s + "!")
.getOrElse("default");
const fallback = Maybe<string>(null)
.map(s => s.toUpperCase())
.getOrElse("default");