Curry Callbacks

curry.js

function callbackCurry(callbacks) {
    var memoize = function memoize(xs) {
        if (!xs.length) return null;

        var tail = xs.slice(1),
            head = xs[0];

        return head.bind(undefined, memoize(tail));
    };

    var curried = memoize(callbacks);
    return curried();
}

var Users = {
    findByScreenName: function(name, cb) {
        return cb({
            id: 12,
            name: name
        });
    },
    getProfile: function(id, cb) {
        return cb({
            id: id,
            name: 'Gianluca',
            last: 'Bargelli',
            age: 29
        });
    }
};

var expected = {
    id: 12,
    name: 'Gianluca',
    last: 'Bargelli',
    age: 29
};

Test.describe('Callback hell');
var profile = Users.findByScreenName('Gianluca', function(user) {
    return Users.getProfile(user.id, function(profile) {
        return profile;
    });
});
Test.deepEquals(profile, expected);

Test.describe('Curry functions');
var profileCurry = callbackCurry([
    function(next) {
        return Users.findByScreenName('Gianluca', next);
    },
    function(next, user) {
        return Users.getProfile(user.id, next);
    },
    function(next, profile) {
        return profile;
    }
]);
Test.deepEquals(profileCurry, expected);

test-runner.js

//
// Simple assertion object (useful for testing functions).
//
var Test = {
    describe: function(label) {
        console.log('\n%s', label);  
    },
    equals: function(sut, expect) {        
        (sut === expect) 
            ? console.log('\t%c ✓ ' + expect, 'color: green') 
            : console.log('\t%c ✗ ' + sut + ' !== ' + expect, 'color: red');
    },
    deepEquals: function(sut, expect) {
        for (var key in expect) {
            if (typeof sut === 'undefined' || !sut[key] || sut[key] !== expect[key]) {
                console.log('\t%c ✗ ' + JSON.stringify(sut) + ' !== ' + JSON.stringify(expect), 'color: red');
                return;
            }
        }

        console.log('\t%c ✓ ' + JSON.stringify(expect), 'color: green');
    }
};