Category Theory - Functor Container Implementation

category-theory-functor-container-implementation.ts

class Container<T> implements Functor<T> {
    private value: T

    constructor(value: T) {
        this.value = value
    }

    fmap<U>(f: (a: T) => U): Functor<U> {
        return new Container(f(this.value))
    }
}

console.log(
    'map integer container to string container:',
    new Container(5).fmap((a) => String(a))
) // Container { value: "5" }