[wroc_love.rb] Migrating to Clojure. So much fn.

Slides from a talk I delivered on 15.03.2014 at wroc_love.rb in Wrocław, Poland.

Migrating a technology stack to a new language is rarely a simple task. It's getting even more challenging when what is changed is not only the language but the whole paradigm. This talk covers a story of stylefruits, where we've been gradually replacing a Ruby-based technology stack serving five million monthly visitors with Clojure. What are the costs and benefits of such a transition? How to make the migration gradual and painless? How to make Ruby and Clojure work with each other on the way? How easy is it to switch from a dynamic, object-oriented language to a functional one based on immutability and laziness? These are just some takeaways from this straight-from-the-trenches report.

Video: https://www.youtube.com/watch?v=Hv4slaRydRM

Transcript

1. Migrating to Clojure So much fn @janstepien
2. I work at
3. I work at
5. © Seph Swain 2008 flickr.com/photos/seph_swain/2735367665
6. (something new)
7. © Seph Swain 2008 flickr.com/photos/seph_swain/2741483308
9. feature freeze! no
10. ↓ ╭────────────╮ │ http proxy │ ╰────────────╯ ↓ ↓ ╭───────────────╮ ╭─────────────╮ │ ruby on rails │ ← │ widgets! │ ╰───────────────╯ ╰─────────────╯ ↓ ╭──────╮ │ db │ ╰──────╯
11. ↓ ╭────────────╮ │ http proxy │ ╰────────────╯ ↓ ↓ ╭───────────────╮ ╭─────────────╮ │ ruby on rails │ │ widgets! │ ╰───────────────╯ ╰─────────────╯ ↓ ↓ ╭──────╮ ╭─────────────╮ │ db │ ← │ data acc. │ ╰──────╯ ╰─────────────╯
12. ↓ ╭───────────────────────╮ │ │ │ ╭───────╯ │ ruby on rails │ ↓ │ │ ╭─────────────╮ │ │ │ widgets! │ ╰───────────────╯ ╰─────────────╯ ↓ ↓ ╭──────╮ ╭─────────────╮ │ db │ ← │ data acc. │ ╰──────╯ ╰─────────────╯
13. /colour-red /50-100-euro /jeans/esprit
14. ↓ ╭───────────────────────╮ │ │ │ ╭───────╯ │ ruby on rails │ ↓ │ │ ╭─────────────╮ │ │ │ widgets! │ ╰───────────────╯ ╰─────────────╯ ↓ ↓ ╭──────╮ ╭─────────────╮ │ db │ ← │ data acc. │ ╰──────╯ ╰─────────────╯
15. ↓ ╭───────────────────────╮ │ │ │ ╭───────╯ │ ruby on rails │ ↓ │ │ ╭─────────────╮ │ │ │ clojure │ ╰───────────────╯ ╰─────────────╯ ↓ ↓ ╭──────╮ ╭─────────────╮ │ db │ ← │ data acc. │ ╰──────╯ ╰─────────────╯
16. +
17. a slide intentionally left blank
18. immutability Object#freeze all the things
19. => (def vector [1 2 3]) => vector [1 2 3] => (conj vector 4) [1 2 3 4] => vector [1 2 3]
20. widgets the cornerstone
21. {:fetch (fn [env] (get-data-for env)) :view (fn [fetched-data] (render fetched-data))}
22. (map render widgets) ↓ (pmap render widgets)
23. templating worst nightmare
24. © omefrans 2010 flickr.com/photos/omefrans/4238610113
25. <div id=”main”> text </div> {:tag :div :attr {:id ”main”} :content [”text”]}
26. repl everywhere
27. => (def vector [1 2 3]) => vector [1 2 3] => (conj vector 4) [1 2 3 4] => vector [1 2 3]
28. nrepl:// repl as a service
29. tools to the rescue
30. community I wish I were that mature
31. languages on jvm all feel like home
32. mistakes we made a lot
33. hiring not as bad as it seems
34. future a lot to be done
35. summing it up it was a good idea
36. Migrating to Clojure So much fn jan.stepien@stylefruits.de jan@stepien.cc @janstepien