More ClojureScript for Engibeering...

app.cljs

; Proper namespaces
(ns app-utils)

; JavaScript interop
(defn -alert [message]
  (js/alert message))

(defn -log [message]
  (.log js/console message))

(ns app
  ; Namespaced module loading
  (:require [app-utils :as utils]))

; Custom Data Types / "OOP"
(deftype Person [name]
  Object
  (welcome [_, level]
    ; Lexical scope, first-class functions, lambdas
    (let [hello (fn [name] (str "Hello, " name "!"))]
    (if (= level "log")
      (utils/-log (hello name))
      (utils/-alert (hello name))))))

; Export to external JavaScript
(defn ^:export build-person [name]
  (Person. name))

; Named parameters and default arguments
(defn ^:export greet
  [person & {:keys [level] :or {level "alert"}}]
  (.welcome person level))

(defn ^:export greet-everyone []
  (greet (Person. "Marco"))
  (greet (Person. "Rebecca") :level "alert")
  (greet (Person. "George") :level "log"))

; Shared state
(def clicks (atom 0))

; Atomic updates to shared state
(defn ^:export click []
  (swap! clicks inc))

(defn ^:export clicks-count []
  @clicks)

; Functional programming, lazy evaluation, infinite sequences
(defn odds-to [n]
  (into [] (filter odd? (take n (range)))))

(defn ^:export sum-of-odds-to [n]
  (reduce + (odds-to n)))

; Resources
; http://clojurescriptone.com/
; https://github.com/clojure/clojurescript
; http://himera.herokuapp.com/index.html
; http://himera.herokuapp.com/synonym.html
; https://developers.google.com/closure/compiler/
; http://dosync.posterous.com/comparing-javascript-coffeescript-clojurescri
; https://github.com/swannodette/mori

app.haml

!!!5
%html
  %head
    %script{type:"text/javascript", src:"https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"}
    %script{type:"text/javascript", src:"app.js"}
    :css
      #clickCount {
        font-size: 250px;
      }
  %body
    #clickCount 0
    :javascript
      $(function() {
        var bryan = app.build_person("Bryan");
        var max = 1000;

        app.greet(bryan);

        $('#clickCount').click(function() {
          app.click();
          $(this).html(app.clicks_count());
        });

        alert(
          "The sum of all odds to " + max + " is: " + app.sum_of_odds_to(max)
        );
      });

one.cljs

(def doc js/document)
(def console js/console)

(js/alert "Hi!")

(.-title doc)

(.log console (.-title doc))

(defn set-html [id value]
  (set!
    (.-innerHTML (.getElementById doc id))
    value))