Clojure/ClojureScript solutions to CodePlus Challenges.

In an effort to show how different languages can be used to stimulate new, outside-the-box ideas and approaches to creating software, I hereby offer my Clojure and ClojureScript solutions to the problems found in the parent directory.

Most of the code here is both Clojure and ClojureScript. For example, every file with the .cljc extension may be compiled by both, with necessary exceptions delineated by the #? or #?@ reader conditionals. Files with the .clj extension are just for Clojure, while .cljs are ClojureScript files.

To play with the code, you'll probably need to have Leiningen installed. On the Mac, I recommend installing via Homebrew, as in brew update; brew install lein. (In fact, if you are on a Mac and just want to dabble at a ClojureScript REPL, you won't need lein. Just run the beautifully self-contained planck, which may also be simply brew installed.) But to run Clojure code — as opposed to ClojureScript — or to build changes and run tests, you'll need the build environment supported by lein.

— Tyler Perkins, May 2016

With Leiningen installed, just run the following at the command line from within the CodePlusChallenges/cljs-solutions/ directory:

lein test

This will build all the source and run all tests, located in test/.

If you have node installed, you can run the provided tests in namespaces specified in file test/test_runner.cljs. Just run this at the command line from CodePlusChallenges/cljs-solutions/:

lein doo node test once

If you're editing files and would like the tests to run automatically when a file is saved, just leave off the once option, above.

Node has no DOM, of course, so if you write some GUI tests requiring the DOM, take a look at the doo documentation. It can run tests in PhantomJS, Chrome, Safari, Firefox, and more.

To play in the Clojure REPL just run the following from CodePlusChallenges/cljs-solutions/. As shown, you'll need to require the namespaces you're interested in and possibly "cd" into one using in-ns:

> cd cljs-solutions/

> lein repl    # Patience, this will take a while!
nREPL server started on port 61997 on host 127.0.0.1 - nrepl://127.0.0.1:61997
REPL-y 0.3.7, nREPL 0.2.12
Clojure 1.8.0
Java HotSpot(TM) 64-Bit Server VM 1.8.0_60-ea-b10
    Docs: (doc function-name-here)
          (find-doc "part-of-name-here")
  Source: (source function-name-here)
 Javadoc: (javadoc java-object-or-class-here)
    Exit: Control+D or (exit) or (quit)
 Results: Stored in vars *1, *2, *3, an exception in *e

user=> (require 'cljs-solutions.problem_1)
nil
user=> (in-ns 'cljs-solutions.problem_1)
#object[clojure.lang.Namespace 0x7c9551d8 "cljs-solutions.problem_1"]
cljs-solutions.problem_1=> (shuf [11 22 33 44])
[22 11 44 33]
cljs-solutions.problem_1=>

As mentioned above, perhaps the simplest way to jump start into a ClojureScript REPL in OS X is to run planck. Note that planck doesn't know anything about the project, such as where source files are located, but it can search for namespaces from the current directory:

> cd src

> planck       # No patience required. This is fast!
Planck 1.14
ClojureScript 1.9.14
    Docs: (doc function-name-here)
          (find-doc "part-of-name-here")
  Source: (source function-name-here)
    Exit: Control+D or :cljs/quit or exit or quit
 Results: Stored in vars *1, *2, *3, an exception in *e

cljs.user=> (require 'cljs-solutions.problem_1)
nil
cljs.user=> (in-ns 'cljs-solutions.problem_1)
nil
cljs-solutions.problem_1=> (shuf [11 22 33 44])
[22 33 44 11]
cljs-solutions.problem_1=>

Note that unlike when we tested above with lein doo node ..., here we are not executing the compiled JavaScript in Node. Planck employs OS X's JavaScriptCore framework to execute in the Mac's built-in JS engine.

You might expect that we can compile our ClojureScript to JavaScript and run it in a browser, but with Figwheel, we can develop using a browser-connected REPL. The solutions here don't make use of it, but Figwheel's killer feature is amazing: When you modify and save an HTML, CSS, JavaScript, or ClojureScript file, it is instantly compiled and sent to the browser!

This can make for a very fluid development workflow as you make changes to the behavior and appearance of your web app in ClojureScript, and instantly see the changes as the app runs. With the everpresent REPL, you can poke around in the running environment, try changing the definition of a function on the fly, examine the state in the page, etc.

To get an interactive development environment run:

lein figwheel

and open your browser at localhost:3449. This will auto compile and send all changes to the browser without the need to reload. After the compilation process is complete, you will get a Browser Connected REPL. An easy way to try it is:

(js/alert "Am I connected?")

and you should see an alert in the browser window.

As above, we can try out shuf in the REPL. Here I'm using rlwrap to create a better line-editing experience. (It is available on the Mac via brew install rlwrap.)

> rlwrap lein figwheel
Figwheel: Validating the configuration found in project.clj

Figwheel: Configuration Valid. Starting Figwheel ...
Figwheel: Starting server at http://0.0.0.0:3449
Figwheel: Watching build - dev
Compiling "resources/public/js/compiled/cljs_solutions.js" from ["src"]...
Successfully compiled "resources/public/js/compiled/cljs_solutions.js" in 1.798 seconds.
Figwheel: Starting CSS Watcher for paths  ["resources/public/css"]
Launching ClojureScript REPL for build: dev
Figwheel Controls:
          (stop-autobuild)                ;; stops Figwheel autobuilder
          (start-autobuild [id ...])      ;; starts autobuilder focused on optional ids
          (switch-to-build id ...)        ;; switches autobuilder to different build
          (reset-autobuild)               ;; stops, cleans, and starts autobuilder
          (reload-config)                 ;; reloads build config and resets autobuild
          (build-once [id ...])           ;; builds source one time
          (clean-builds [id ..])          ;; deletes compiled cljs target files
          (print-config [id ...])         ;; prints out build configurations
          (fig-status)                    ;; displays current state of system
  Switch REPL build focus:
          :cljs/quit                      ;; allows you to switch REPL to another build
    Docs: (doc function-name-here)
    Exit: Control+C or :cljs/quit
 Results: Stored in vars *1, *2, *3, *e holds last exception object
Prompt will show when Figwheel connects to your application
To quit, type: :cljs/quit
cljs.user=> (require 'cljs-solutions.problem_1)
nil
cljs.user=> (in-ns 'cljs-solutions.problem_1)
nil
cljs-solutions.problem_1=> (shuf [11 22 33 44])
[44 33 22 11]
cljs-solutions.problem_1=>

To clean all compiled files:

lein clean

Copyright © 2016

Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.