Option<T> monad for TS

option.ts

export class Option<T> {

    _value: T;

    constructor(object: T) {
        this._value = object;
    }

    static empty<T>(): Option<any> {
        return new Option<T>(null);
    }

    static from<T>(nonNullableObject: T): Option<T> {
        if (nonNullableObject === undefined) {
            throw new Error('Option<T>: Given object must be non-null.');
        }
        return new Option<T>(nonNullableObject);
    }

    static fromNullable<T>(nullableObject: T): Option<T> {
        return new Option<T>(nullableObject);
    }

    isPresent(): boolean {
        return this._value !== null;
    }

    map<U>(f: (input: T) => U): Option<U> {
        if (!this.isPresent()) {
            return Option.empty();
        }
        return new Option<U>(f(this._value));
    }

    getOrElse(defaultValue: T): T {
        if (!this.isPresent()) {
            return defaultValue;
        }
        return this._value;
    }

    ifPresent(f: (input: T) => void) {
        if (this.isPresent()) {
            f(this._value);
        }
    }
}