The Ideas of Clojure - Things I learn from Clojure
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The document summarizes some of the key ideas and philosophies of the Clojure programming language as presented by Randy Lien. Some of the main points covered include: - Clojure focuses on simplicity, empowerment, and expressiveness through features like pure functions, immutability, and consistent syntax. - Clojure allows leveraging existing libraries from Java and JavaScript through its ability to run on the JVM and as ClojureScript. - The REPL-driven development model and immutable persistent data structures make Clojure well-suited for functional programming.
![Data Types (cont.)
• Symbols - bar
• Keywords - :foo
• Booleans - true false
• Null - nil
• Regex - #"[A-Z0-9._%+-]+@[A-Z0-9.-]+.[A-Z]+"](https://image.slidesharecdn.com/theideasofclojure-jcconf-151206162725-lva1-app6891/85/The-Ideas-of-Clojure-Things-I-learn-from-Clojure-23-320.jpg)
![Data Structure
• Lists - (1 2 3)
• Prepend
• Vectors - [1 2 3]
• Zero indexed. Append
• Maps - {:a 1, :b 2, :c "3"}
• Key-value pair
• Comma will be ignored
• Sets - #{1 2 3}
• Unique. Unordered](https://image.slidesharecdn.com/theideasofclojure-jcconf-151206162725-lva1-app6891/85/The-Ideas-of-Clojure-Things-I-learn-from-Clojure-24-320.jpg)
![Clojure
• (+ 1 2)
• (+ 1 2 3)
• (into [] 2)
General
• 1 + 2
• 1 + 2 + 3
• [].push(2)](https://image.slidesharecdn.com/theideasofclojure-jcconf-151206162725-lva1-app6891/85/The-Ideas-of-Clojure-Things-I-learn-from-Clojure-27-320.jpg)
The Ideas of Clojure - Things I learn from Clojure
- 1. THE IDEAS OF CLOJURE JCConf 2015/12/04 Randy Lien Things I learn from Clojure
- 3. Survey! • Heard Clojure? • Clojure developer? • Enjoy Java development?
- 4. “I don’t know Java.” – Speaker
- 6. History of programming languages
- 7. LISP
- 8. Clojure ?
- 10. Tapestry Dude - https://goo.gl/R5m3am (CC BY-SA 2.0) The Creator of Clojure Rich Hickey
- 11. "Hickey is the new Messiah of software development. Watch and listen to his talks, and you will understand." – http://bepsays.com/2014/07/08/how-rich-is-rich-hickey/
- 12. Few ideas I want to share
- 13. Philosophy
- 14. Philosophy Focus Simplicity Empowerment Pure functions Expressive Practical Clarity Consistency Separation of concerns Concise Direct Interop - The Joy of Clojure
- 15. Philosophy - Simplicity • Pure functions • Immutable • Simple abstractions • defprotocol • deftype
- 16. Philosophy - Focus • Syntax will not bother you • Consistency • Dynamic System • Almost everything defined in Clojure can be redefined (Even while program is running) • Use Macro you can build anything you want to do
- 17. Philosophy - Empowerment • Use Java Virtual Machine • Java is mature and has many libraries • JavaScript is everywhere (ClojureScript)
- 18. Consistency
- 20. Java + Python + JavaScript ?
- 21. JaPythonScript?
- 22. Data Types • Integers - 123 • Doubles - 1.23 • Ratios - 1/23 • Strings - "JCConf" • "Double Quotes Only" • Characters - J C
- 23. Data Types (cont.) • Symbols - bar • Keywords - :foo • Booleans - true false • Null - nil • Regex - #"[A-Z0-9._%+-]+@[A-Z0-9.-]+.[A-Z]+"
- 24. Data Structure • Lists - (1 2 3) • Prepend • Vectors - [1 2 3] • Zero indexed. Append • Maps - {:a 1, :b 2, :c "3"} • Key-value pair • Comma will be ignored • Sets - #{1 2 3} • Unique. Unordered
- 27. Clojure • (+ 1 2) • (+ 1 2 3) • (into [] 2) General • 1 + 2 • 1 + 2 + 3 • [].push(2)
- 29. Use host libraries - Java
- 30. Use host libraries - JavaScript
- 31. DEMO
- 33. functions & composition • map, reduce, filter • partial, comp • iterate • repeat, repeatedly • Many built-in functions and you don’t need to create. Just compose it!
- 34. DEMO
- 35. Values
- 36. Values should be… • Value! • operated by functions • time-relative • Immutable
- 37. Why Immutable?
- 38. Why mutable?
- 39. Why mutable? • Limitations of early computers: Small RAM and disk • New information replaces old
- 40. Why immutable? • No resource limitation • Persistent data structure • Record - Share the same data • Key to do functional programming • No side effect • atom is mutable
- 42. REPL ? • Read–Eval–Print Loop • nREPL (network REPL) • Good for doing TDD • clojure.test • ClojureScript - Browser can connect to nREPL
- 47. Leiningen
- 48. Summary
- 49. Summary • Clojure is a practical functional programming language • Java and JavaScript are two major languages and Clojure and ClojureScript can run on them • Using REPL in your TDD practices would be helpful • Pure functions and Immutable data structure can make your system stable and easy to reason about
- 50. Summary (cont.) • Clojure has much better tooling and keep improving it • ClojureScript is hotter than Clojure! • Many companies are using Clojure • booking.com, Yahoo, Puppet, Walmart, twitter, heroku, nubank…etc • STM, transducer, core.asyn
- 51. If you want to know more… • Living Clojure • The Joy of Clojure • ClojureScript Unraveled • Clojure Applied • Clojure for the Brave and True
- 52. Online resource • http://www.tryclj.com/ • http://www.4clojure.com/
- 54. Worth to watch • Simple Made Easy • Clojure Made Simple • The Value of Values • The Language of the System
- 55. Thanks