Function optional

optional<T, U>(
value: T | null | undefined,
fn: (value: T) => Maybe<U>,
): Maybe<U>
flatMap(fromNullable(value), fn) — lift a nullable then bind through a Maybe-returning step. Convenient for chaining lookups.
Type Parameters
- T
- U
Parameters
- value: T | null | undefined
- fn: (value: T) => Maybe<U>
Returns Maybe<U>
Example
```
optional(rawId, (id) => fromNullable(cache.get(id)));
```
- Defined in maybe.ts:222