clojurescript-om-adventures

First play with Clojurescript and Om (Basic Tutorial)

Overview

Following along, trying to document as much as I can about Clojurescript

Setup

1. Install Leiningen

2. Install rlwrap (for cursor key sanity) Ubuntu

To get an interactive development environment run:

rlwrap 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.

To clean all compiled files:

lein clean

To create a production build run:

lein cljsbuild once min

And open your browser in resources/public/index.html. You will not get live reloading, nor a REPL.

Stuff to play with

• Switch namespace to application namespace => (in-ns 'om-tut.core)

• Lets deref app-state atom (prints it out in REPL) => @app-state

• Add an additional contact => (swap! app-state update-in [:contacts] conj {:first "Benji" :last "Soar"})

• Update the firstname of our second contact in our vector => (swap! app-state update-in [:contacts 1] assoc :first (str "Alice " "In Wonderland"))

With your browser connected to the REPL the updates should be immediate! MAGIC!

Protip!

(swap! app-state update-in [:contacts 1] assoc :first (str "Alice " "In Wonderland"))

If we deconstruct this, we're invoking the swap! function which will apply the update-in function to the current atom state app-state.

The update-in function allows us to change the value in a map at a specific key path. It takes a sequence of keys [:contacts 1] (the path within the map to the value we want to update) and a function assoc that will take the old value plus any arguments supplied to it :first (str "Alice " "In Wonderland")

Simples! :)