Functional Ruby
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The document discusses Mikhail Bortnyk's background as a Ruby developer and language researcher, highlighting his work with the functional-ruby gem, which introduces functional programming concepts into Ruby. Key topics include the problems with object-oriented programming, the principles of functional programming, and the implementation of pattern matching, immutability, and function memoization in the functional paradigm. It concludes with an overview of the functionality provided by the functional-ruby gem, supported by real code snippets.
Functional Ruby
- 3. ABOUT ME • Mikhail Bortnyk
- 4. ABOUT ME • Mikhail Bortnyk • Too old for this shit
- 5. ABOUT ME • Mikhail Bortnyk • Too old for this shit • Work for Amoniac OÜ
- 6. ABOUT ME • Mikhail Bortnyk • Too old for this shit • Work for Amoniac OÜ • Ruby developer
- 7. ABOUT ME • Mikhail Bortnyk • Too old for this shit • Work for Amoniac OÜ • Ruby developer • Language researcher
- 8. ABOUT ME • Mikhail Bortnyk • Too old for this shit • Work for Amoniac OÜ • Ruby developer • Language researcher • kottans.org co-founder
- 9. ABOUT ME • Mikhail Bortnyk • Too old for this shit • Work for Amoniac OÜ • Ruby developer • Language researcher • kottans.org co-founder • twitter @mikhailbortnyk
- 12. SIDE EFFECTS PROBLEM 1.1 • your objects store state
- 13. SIDE EFFECTS PROBLEM 1.1 • your objects store state • your code modifies state
- 14. SIDE EFFECTS PROBLEM 1.1 • your objects store state • your code modifies state • your other code modifies state too
- 15. SIDE EFFECTS PROBLEM 1.1 • your objects store state • your code modifies state • your other code modifies state too • summary: mess
- 16. SIDE EFFECTS PROBLEM 1.1 • your objects store state • your code modifies state • your other code modifies state too • summary: mess
- 17. DATA/CODE ENTITY SHARING PROBLEM 1.2 • your model stores both your logic and data
- 18. DATA/CODE ENTITY SHARING PROBLEM 1.2 • your model stores both your logic and data • nuff said
- 19. DATA/CODE ENTITY SHARING PROBLEM 1.2 • your model stores both your logic and data • nuff said
- 21. HYPE PROBLEM 1.3 • Erlang • Haskell
- 22. HYPE PROBLEM 1.3 • Erlang • Haskell • Scala
- 23. HYPE PROBLEM 1.3 • Erlang • Haskell • Scala • OCaml
- 24. HYPE PROBLEM 1.3 • Erlang • Haskell • Scala • OCaml • Lisp
- 25. HYPE PROBLEM 1.3 • Erlang • Haskell • Scala • OCaml • Lisp • Javascript (sic!)
- 26. HYPE PROBLEM 1.3 • Erlang • Haskell • Scala • OCaml • Lisp • Javascript (sic!) • Ruby (sic!)
- 27. PART TWO EASY (NOT REALLY) LEVEL
- 28. LIMITS ARE FREEING CLEAN YOUR RUBY • David Copeland article “Adventures in functional programming with Ruby”
- 29. LIMITS ARE FREEING CLEAN YOUR RUBY • David Copeland article “Adventures in functional programming with Ruby” • Loops are just functions
- 30. LIMITS ARE FREEING CLEAN YOUR RUBY • David Copeland article “Adventures in functional programming with Ruby” • Loops are just functions • Data structures are just functions
- 31. LIMITS ARE FREEING CLEAN YOUR RUBY • David Copeland article “Adventures in functional programming with Ruby” • Loops are just functions • Data structures are just functions • Objects are just functions
- 32. LIMITS ARE FREEING CLEAN YOUR RUBY • David Copeland article “Adventures in functional programming with Ruby” • Loops are just functions • Data structures are just functions • Objects are just functions • Namespaces are just functions
- 33. LIMITS ARE FREEING CLEAN YOUR RUBY • David Copeland article “Adventures in functional programming with Ruby” • Loops are just functions • Data structures are just functions • Objects are just functions • Namespaces are just functions • P.S. Ruby HAS Tail Call Optimization
- 34. ROUGH HACK TAIL-CALL OPTIMIZATION def fact(n, acc=1) return acc if n <= 1 fact(n-1, n*acc) end RubyVM::InstructionSequence.compile_option = { tailcall_optimization: true, trace_instruction: false } fact(1000)
- 35. FUNCTIONAL VS OBJECT-ORIENTED SIDE TO SIDE COMPARISON new_person = ->(name, birthdate, gender, title, id=nil) { return ->(attribute) { return id if attribute == :id return name if attribute == :name return birthdate if attribute == :birthdate return gender if attribute == :gender return title if attribute == :title nil } } class Person attr_reader :id, :name, :birthdate, :gender, :title def initialize(name, birthdate, gender, title, id=nil) @id = id @name = name @birthdate = birthdate @gender = gender @title = title end end
- 36. SPECIAL KNOWLEDGE WHAT’S WRONG WITH OO-CODE? • WTF is “class”
- 37. SPECIAL KNOWLEDGE WHAT’S WRONG WITH OO-CODE? • WTF is “class” • WTF are .new and initialize
- 38. SPECIAL KNOWLEDGE WHAT’S WRONG WITH OO-CODE? • WTF is “class” • WTF are .new and initialize • API of class
- 39. SPECIAL KNOWLEDGE WHAT’S WRONG WITH OO-CODE? • WTF is “class” • WTF are .new and initialize • API of class • WTF are @-variables
- 40. SPECIAL KNOWLEDGE WHAT’S WRONG WITH OO-CODE? • WTF is “class” • WTF are .new and initialize • API of class • WTF are @-variables • difference between class and instance
- 41. SPECIAL KNOWLEDGE WHAT’S WRONG WITH OO-CODE? • WTF is “class” • WTF are .new and initialize • API of class • WTF are @-variables • difference between class and instance • WTF is “attr_reader”
- 42. NO HIDDEN MAGIC FUNCTIONAL PROGRAMMING CODE • how to define function
- 43. NO HIDDEN MAGIC FUNCTIONAL PROGRAMMING CODE • how to define function • how to call function
- 44. TO DON’T SHOOT YOUR LEG SAFETY RULES • do not modify, create new
- 45. TO DON’T SHOOT YOUR LEG SAFETY RULES • do not modify, create new • BUY MORE RAM
- 46. TO DON’T SHOOT YOUR LEG SAFETY RULES • do not modify, create new • BUY MORE RAM • functions should not depend on environment
- 47. TO DON’T SHOOT YOUR LEG SAFETY RULES • do not modify, create new • BUY MORE RAM • functions should not depend on environment • BUY EVEN MORE RAM
- 48. TO DON’T SHOOT YOUR LEG SAFETY RULES • do not modify, create new • BUY MORE RAM • functions should not depend on environment • BUY EVEN MORE RAM • avoid returns
- 49. TO DON’T SHOOT YOUR LEG SAFETY RULES • do not modify, create new • BUY MORE RAM • functions should not depend on environment • BUY EVEN MORE RAM • avoid returns • use lambdas
- 50. TO DON’T SHOOT YOUR LEG SAFETY RULES • do not modify, create new • BUY MORE RAM • functions should not depend on environment • BUY EVEN MORE RAM • avoid returns • use lambdas • DO NOT FORGET TO ORDER RAM RIGHT NOW
- 51. SIDE TO SIDE RULES COMPARISON FUNCTIONAL VS OBJECT-ORIENTED • how to perform tasks and how to track changes • state changes are important • order of execution is important • flow controlled by loops, conditionals, function calls • instances of structures and classes • focus on what information is needed and what transformations required • state changes are non-existent • order of execution is low- important • flow controlled by function calls including recursion • functions are first class objects, data collections
- 52. — Greenspun’s tenth rule of programming ANY SUFFICIENTLY COMPLICATED C OR FORTRAN PROGRAM CONTAINS AN AD-HOC, INFORMALLY-SPECIFIED, BUG-RIDDEN, SLOW IMPLEMENTATION OF HALF OF COMMON LISP. ” “
- 53. PART THREE I AM DEVELOPER, I DON’T WANT TO LEARN, I WANT PATTERN MATCHING AND IMMUTABILITY
- 54. STILL EVOLVING! FUNCTIONAL-RUBY GEM • created by Jerry D’Antonio
- 55. STILL EVOLVING! FUNCTIONAL-RUBY GEM • created by Jerry D’Antonio • inspired by Erlang, Clojure, Haskell and Functional Java
- 56. STILL EVOLVING! FUNCTIONAL-RUBY GEM • created by Jerry D’Antonio • inspired by Erlang, Clojure, Haskell and Functional Java • has records, unions and tuples
- 57. STILL EVOLVING! FUNCTIONAL-RUBY GEM • created by Jerry D’Antonio • inspired by Erlang, Clojure, Haskell and Functional Java • has records, unions and tuples • has protocols
- 58. STILL EVOLVING! FUNCTIONAL-RUBY GEM • created by Jerry D’Antonio • inspired by Erlang, Clojure, Haskell and Functional Java • has records, unions and tuples • has protocols • has Erlang-style pattern matching
- 59. STILL EVOLVING! FUNCTIONAL-RUBY GEM • created by Jerry D’Antonio • inspired by Erlang, Clojure, Haskell and Functional Java • has records, unions and tuples • has protocols • has Erlang-style pattern matching • has function memoization
- 60. STILL EVOLVING! FUNCTIONAL-RUBY GEM • created by Jerry D’Antonio • inspired by Erlang, Clojure, Haskell and Functional Java • has records, unions and tuples • has protocols • has Erlang-style pattern matching • has function memoization • supports MRI, JRuby and Rubinius
- 62. PATTERN MATCHING AND TYPE CHECKING FUNCTIONAL-RUBY GEM class Yoga include Functional::PatternMatching include Functional::TypeCheck defn(:where_is_sun) do puts "o" end defn(:where_is_sun, 14) do puts "88!" end defn(:where_is_sun, _) do |name| puts "o, #{name}!" end defn(:where_is_sun, _) do |name| puts "Are you in wrong district, #{name.rude_name}?" end.when { |name| Type?(name, Moskal) } defn(:where_is_sun, _, _) do |name, surname| "o, #{name} #{surname}!" end end
- 63. MEMOIZATION FUNCTIONAL-RUBY GEM class Factors include Functional::Memo def self.sum_of(number) of(number).reduce(:+) end def self.of(number) (1..number).select {|i| factor?(number, i)} end def self.factor?(number, potential) number % potential == 0 end memoize(:sum_of) memoize(:of) end
- 64. RECORDS FUNCTIONAL-RUBY GEM Name = Functional::Record.new(:first, :middle, :last, :suffix) do mandatory :first, :last default :first, 'J.' default :last, 'Doe' end
- 65. QUESTION
- 66. Q&A
- 67. THANK YOU