developing Laravel 3 and laravel 4

Laravel 4 is currently in beta 1 with beta 2 coming this or probably next week. To answer your question directly: yes your Laravel 3 (L3) application will break in Laravel 4 (L4) because L4 differs in quite a few points from L3. But L4 was designed with migrating from L3 installs in mind so you definitely don't have to rewrite your entire application. You probably only need to update some routes, functions and implement some new ways L4 handles certain key aspects. Like others stated here, a migration guide isn't available yet but you can bet that when L4 gets released a lot of tutorials and guides will be made available.

You're not losing time learning L3 since much of L4 is still the same as L3. The docs of L4 will help you transfer from L3 to L4. Taylor said (and I agree) that you shouldn't wait until L4 gets finished. If you want to build an app and release it for production soon just go with L3 and migrate later on.

The way L4 implements bundles differs from L3. L4 uses composer to install dependencies into the framework. You can always still use bundles directly in the app but they probably need to be updated to work along nicely with the updates in L4.

To start learning L4 the documentation is a great way to do so. You won't learn everything but work isn't done on the docs either. There's more to come as more betas get released.

If you want to learn more about L4 here are a few nice tutorials to get you started:

• What to expect from Laravel 4 by nettuts.com
• Laravel 4 tutorials by Jason Lewis

There's much more out there but this should get you started :)

This should hopefully answer all of your questions: http://four.laravel.com/

I haven't seen a migration guide yet, but then I haven't looked too hard. I'm sure if there isn't one yet, there will be soon