This weekend in the Intertweets (Dec 20th Ed)

• Pre/Post conditions for functions coming in #clojure 1.1 (here, via @thebusby)

(defn constrained-sqr [x]
    {:pre  [(pos? x)]
     :post [(> % 16), (< % 225)]}
    (* x x))

• #clojure promise function implementation is 10 lines! (here, via @wmacgyver)

(defn promise
  "... (edited) ..."
  []
  (let [d (java.util.concurrent.CountDownLatch. 1)
        v (atom nil)]
    (proxy [clojure.lang.AFn clojure.lang.IDeref] []
      (deref [] (.await d) @v)
      (invoke [x]
        (locking d
          (if (pos? (.getCount d))
            (do (reset! v x)
                (.countDown d)
                this)
            (throw (IllegalStateException. "Multiple deliver calls to a promise"))))))))

• Tail-call implementation for the JVM (here, via @mikedouglas) — a patch to the JVM source code that would provide TCI… if this patch exists and it works, does this mean we will see TCI in the JVM in our lifetime?
• Tutorial: Continuation Monad in Clojure (here, via @timbray) — If you understand monads, then I guess you’ll find this tutorial ‘easy’.
• The Parenophobes strike again (here, via @kotarak) — A defense of the lisp syntax from repeated attacks. Speaking to deaf ears maybe? Nonetheless, a good article.
• Finally completely automated process of setting up Clojure, clojure-contrib, and vimclojure on new Linux installs (here, via @jakemcc) —  Related blog posts about how the scripts work here, here and here.
• Setting up #Clojure, #Incanter, Emacs, Slime, Swank, and Paredit (here, via @liebke) — “I’ll be demonstrating how to build and install Incanter (which includes Clojure and Clojure-contrib), and then set up a development environment with Emacs, Slime, Swank, and Paredit.”
• Adder: Python with a Lisp: lisp-1 compiled to #python bytecode like #clojure (here, via @jneira) — so, for when a clojure that runs on the python VM?
  • From the project page: “Clojure has prepared the ground for the notion of a Lisp that integrates into an existing language” (via @stuartsierra)
• The Arc Challenge from a Clojure perspective (here, via @laujensen) — While showing how Clojure is a very terse language by comparing it to Paul Graham’s Arc (and as a response to Paul Graham’s challenge), Lau produces a web application that is the best example of the use of Compojure that I have seen so far (best as in smallest but complete)
• Unit testing in Clojure (here, via @aberant) — I must have missed this one in November, but this is a nice tutorial on creating and running unit tests in clojure.
• Mapping OOPS concepts to Clojure? Doable or Wrong thinking? (here, via @ajlopez) — Walking into a hornets’ nest, maybe?