Natural language constructs in JS

createSentence.js

var createSentence = function () {
    var names = [].slice.call(arguments);
    var fn = names.pop();

    if ( names.length === 0 ) {
        return fn;
    }

    var name = names.shift();

    return function (value) {
        var obj = {};

        obj[name] = createSentence.apply(null, names.concat(fn.bind(null, value)));

        return obj;
    };
};

spec.js

describe("createSentence", function () {
    it("should create a one-level chain given one name", function () {
        var combine = createSentence("with", function (a, b) {
            return a + " " + b;
        });

        combine("foo").with("bar").should.equal("foo bar");
    });

    it("should create a two-level chain given two names", function () {
        var createPerson = createSentence("withFirstName", "withLastName", function (nickName, firstName, lastName) {
            return {
                nickName: nickName,
                firstName: firstName,
                lastName: lastName
            };
        });

        createPerson("blackjack").withFirstName("Jack").withLastName("Black").should.deep.equal({
            nickName: "blackjack",
            firstName: "Jack",
            lastName: "Black"
        });
    });
});