Episode 004: Atomic Curls
Christoph tries to make tic-tac-toe work over the Internet and discovers the power of the atom.
- Let’s get a web framework, build a UI, hook that up to an HTTP API, throw in some websockets for notifications!
- “We’d end up with our first 12 hour podcast episode.”
- A “tracer bullet”: get something functioning to see the important parts of the solution.
- Can choose when to replace important parts by something more “production worthy”.
- “Let’s just ditch all the complexity of having a UI and just use
curlwill print the text response. We have a terminal UI!
- “We’re extending the command line out to the web!”
- “I just keep curling every day or every other day until it’s my turn.”
- “It’s your morning curls!”
- How do we handle web requests? What is a route?
- “Super simple URL API. Who needs REST?”
- Let’s run this on port
1337to hide it from the Internet.
- One shared game state stored in an atom. It’s the only game in town!
- Use an atom instead of a database to cut complexity while problem solving.
reset!indicates you’re causing a side effect.
- Handler’s sole job: take web requests and alter the game state using the game model.
- Function called by
swap!should be pure. Don’t throw exceptions!
- Dilemma: How much do you put inside the function called by “swap!”?
- For errors, the transaction function can:
- Return unchanged reference. Use “triage” function to diagnose.
- Have an “error” attribute in the state and set an “outcome” code like
- Tracer bullet shows lots of ways to complex-ify this into “Tic-Tac-Toe, Enterprise Edition”
Clojure in this episode: