[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
   

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2. I work at
   

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3. I work at
   

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4. View Slide

5. © Seph Swain 2008
   flickr.com/photos/seph_swain/2735367665
   

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6. (something
   new)
   

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7. © Seph Swain 2008
   flickr.com/photos/seph_swain/2741483308
   

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9. feature freeze!
   no
   

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10. ↓
    ╭────────────╮
    │ http proxy │
    ╰────────────╯
    ↓ ↓
    ╭───────────────╮ ╭─────────────╮
    │ ruby on rails │ ← │ widgets! │
    ╰───────────────╯ ╰─────────────╯
    ↓
    ╭──────╮
    │ db │
    ╰──────╯
    

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11. ↓
    ╭────────────╮
    │ http proxy │
    ╰────────────╯
    ↓ ↓
    ╭───────────────╮ ╭─────────────╮
    │ ruby on rails │ │ widgets! │
    ╰───────────────╯ ╰─────────────╯
    ↓ ↓
    ╭──────╮ ╭─────────────╮
    │ db │ ← │ data acc. │
    ╰──────╯ ╰─────────────╯
    

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12. ↓
    ╭───────────────────────╮
    │ │
    │ ╭───────╯
    │ ruby on rails │ ↓
    │ │ ╭─────────────╮
    │ │ │ widgets! │
    ╰───────────────╯ ╰─────────────╯
    ↓ ↓
    ╭──────╮ ╭─────────────╮
    │ db │ ← │ data acc. │
    ╰──────╯ ╰─────────────╯
    

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13. /colour-red
    /50-100-euro
    /jeans/esprit
    

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14. ↓
    ╭───────────────────────╮
    │ │
    │ ╭───────╯
    │ ruby on rails │ ↓
    │ │ ╭─────────────╮
    │ │ │ widgets! │
    ╰───────────────╯ ╰─────────────╯
    ↓ ↓
    ╭──────╮ ╭─────────────╮
    │ db │ ← │ data acc. │
    ╰──────╯ ╰─────────────╯
    

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15. ↓
    ╭───────────────────────╮
    │ │
    │ ╭───────╯
    │ ruby on rails │ ↓
    │ │ ╭─────────────╮
    │ │ │ clojure │
    ╰───────────────╯ ╰─────────────╯
    ↓ ↓
    ╭──────╮ ╭─────────────╮
    │ db │ ← │ data acc. │
    ╰──────╯ ╰─────────────╯
    

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16. +
    

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17. a slide intentionally left blank
    

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18. immutability
    Object#freeze all the things
    

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19. => (def vector [1 2 3])
    => vector
    [1 2 3]
    => (conj vector 4)
    [1 2 3 4]
    => vector
    [1 2 3]
    

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20. widgets
    the cornerstone
    

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21. {:fetch (fn [env]
    (get-data-for env))
    :view (fn [fetched-data]
    (render fetched-data))}
    

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22. (map render widgets)
    ↓
    (pmap render widgets)
    

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23. templating
    worst nightmare
    

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24. © omefrans 2010
    flickr.com/photos/omefrans/4238610113
    

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25. 
    text
    
    {:tag :div
    :attr {:id ”main”}
    :content [”text”]}
    

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26. repl
    everywhere
    

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27. => (def vector [1 2 3])
    => vector
    [1 2 3]
    => (conj vector 4)
    [1 2 3 4]
    => vector
    [1 2 3]
    

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28. nrepl://
    repl as a service
    

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29. tools
    to the rescue
    

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30. community
    I wish I were that mature
    

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31. languages
    on jvm all feel like home
    

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32. mistakes
    we made a lot
    

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33. hiring
    not as bad as it seems
    

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34. future
    a lot to be done
    

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35. summing it up
    it was a good idea
    

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36. Migrating to Clojure
    So much fn
    jan.stepien@stylefruits.de
    jan@stepien.cc
    @janstepien
    

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