greeter.ts

interface Language {
    greet(name: string) : string
    //shout(name: string) : string
}

function English () : Language {
    function greet (name) {
        return 'Hello, ' + name;
    }
    return {
        greet
    };
}

function Xhosa () : Language {
    function greet (name) {
        return 'Molo, ' + name;
    }
    return {
        greet
    };
}

function Afrikaans() : Language {
    function greet(name) {
        return "Goeie more, " + name;
    }

    return {
        greet
    }
}

function Person (language: Language)  {
    function greet (name) {
        return language.greet(name);
    }

    return {
        greet
    };
}

let person = Person({
    greet : function(name) {
        return "Yo, " + name;
    }
});

console.log(person.greet('Andre'));