Programming Clojure Beta 9 is now available. We are almost done, and most of the changes in this Beta are small.

What's new:

• the notation conventions have changed to make console output and REPL results more distinct
• a new subsection covering functions on vectors
• a new subsection on sort functions
• an example using map with more than one collection
• an example using the :while option to a sequence comprehension
• examples now use the new letfn form where appropriate
• replicate is gone – use repeat instead
• an index!

I have also made the book more strict in discussions of laziness. Clojure sequences are lazy, but function evaluation is eager. In the Clojure community we often ignore this distinction, saying things like "iterate is lazy" when we really should say "iterate returns a lazy sequence." The book now uses the latter formulation.

To make sure you have the latest, greatest version of the sample code from the book, go and grab the github repo.

Thanks again to everyone who has been offering feedback. Keep the feedback coming!