Get Functional Programming with Clojure
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An overview of Functional Programming and Clojure, helping you understand the importance of minimising side effects and walking through examples of functional programming concepts.
![Persistent Data Structures
(list 1 2 3 4 5) ‘(“fish” “chip” 42)
(vec ‘(1 2 3 4)) [1 2 3 4]
{:key “value} {:name “John” :skill “talking in full rooms”}
(set ‘(1 2 3 4 4)) #{1 2 3 4}](https://image.slidesharecdn.com/getfunctionalprogrammingwithclojure-160226114702/85/Get-Functional-Programming-with-Clojure-12-320.jpg)
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Get Functional Programming with Clojure
- 1. Get into Functional Programming with Clojure by John Stevenson @jr0cket clojure.practical.li
- 3. Why Functional Programming it's not just because it's really fun...
- 4. OO Software in action Josh Smith - Tweet
- 5. The Complexity Iceberg - @krisajenkins ● complexity is very dangerous when hidden ● You can't know what a function does for certain if it has side effects
- 6. Side Effects
- 7. Pure Functions The results of the function are purely determined by its initial output and its own code - no external influence, a function only uses local values - referential transparency (the function can be replaced by its value)
- 8. Impure Functions - side causes The results of the function are purely determined by its initial output and its own code - behaviour externally influenced and non-deterministic
- 9. Eliminating Side Effects Functional programming is about eliminating side effects where you can, controlling them where you can't - @krisajenkins The features in Functional Programming come from a desire to reduce side effects
- 10. Clojure General purpose language hosted on JVM, JavaScript & CLR
- 11. Clojure / ClojureScript A hosted language with simple interoperability with the host language - (java.Util.Date.) - (js/alert “Client side apps are easier in Clojure”)
- 12. Persistent Data Structures (list 1 2 3 4 5) ‘(“fish” “chip” 42) (vec ‘(1 2 3 4)) [1 2 3 4] {:key “value} {:name “John” :skill “talking in full rooms”} (set ‘(1 2 3 4 4)) #{1 2 3 4}
- 15. Higher Order Functions Functions always return a value & can be used as an argument to another function - Chain functions over a data structure
- 16. Composing functions together Example: current value of the Clojure project from the configuration file - `slurp` in the project file, convert into a string and return the value at index 2
- 17. Recursion Process a collection of values by feeding the remaining elements back to the function - the sum function has different behaviour depending on if passed 1 or 2 arguments
- 18. Recursion - tail call optomisation Protect the heap space from blowing by using the recur function
- 19. Lazy Evaluation Only return a value when necessary ● maintain precision ● optomise evaluation
- 20. Sequence / List Comprehension
- 21. Sequence / List Comprehension Iterating through a range of generated values to create a list of 2 value vectors
- 22. Concurrency is Easier Concurrency is much easier to write and reason about because of - Immutability by default - Persistent Data Structures - values are immutable - functional isolation & pure functions - state changes managed atomically (software transactional memory) - core.async library allows you to write asynchronous code as easily as sequential code
- 23. Safe State changes Changing state safely by not changing it ● Persistent data structures ● Local bindings Changing state safely by changing it atomically ● Software Transactional Memory (STM) ○ Gives an mechanism like an in-memory atomic database that manages mutable state changes under the covers ● Atoms ● core.async
- 24. Concurrency syntax - atoms An online card game has players that can join and have their winnings tracked
- 25. Concurrency syntax - atoms The join-game function adds players to the atom by their name, but only up to 2 players
- 26. Concurrency syntax - refs for sync updates The join-game-safely adds players to the ref and alters their account & game account
- 27. Putting it all together Let's find all the most common words used in a popular Science Fiction novel
- 28. Clojure General purpose language hosted on JVM, JavaScript & CLR
- 29. Tools to learn Clojure inspire them & build up their motivation
- 30. Clojure support in many different tools
- 31. Leiningen - Clojure powered build automation
- 35. Figwheel (flappy birds example)
- 37. Examples, examples, examples we learn by example...
- 38. Over 20 Books on Clojure... Where to start with Clojure will be different... Example: I typically suggested BraveClojure.com as a starting point, however many people prefer LivingClojure or ClojureScript Unraveled... Help people understand the relevance of a book and if it's the right thing for them at that time.
- 41. Github
- 45. Testing your Clojure skills...
- 47. Clojurian Community in Person Probably the most active language-specific developer communities in London
- 48. Learning by teaching others I really started thinking in Clojure when I started talking to & teaching others - Coding dojos - talks on Clojure (starting with the basics, showing the art of the possible) - moving on to running conferences - workshops at hack days
- 49. Overtone live performance - MetaX
- 50. Overtone live performance - MetaX
- 51. Take your own journey into Clojure