I've found a better title for my book: Executable Specifications. Listen to find out why it's better.

I'm organizing my new book in terms of lenses. Each lens focuses our attention on one important aspect of software design. In this episode, I briefly introduce each lens.

I talk about the progress I've made on my book and why I'm throwing it away and starting over.

I give another reason why I don't encounter so many type errors in Clojure.

Watch the creation of a simple refactoring to turn functions into data.

One important skill in domain modeling is learning to see the semantics of your language, past the habits you've developed. To do that, it helps to see the same example in multiple languages. So how do I show examples in multiple languages without expanding the size of my book?

An isomorphism is a one-to-one mapping from two sets, and encoding your domain model involves finding a mapping between the real world and your code. So does domain modeling involve isomorphism?

Domain modeling also works after you've already got lots of code. How can we apply domain modeling analysis to existing data structures?

We discuss the commutative property, why we use it, and three different possible meanings.

We look at several examples where the associative property gives us expressive power.