Functional Programming and Java8

Functional Programming and Java8

• 1.
  functional programmingand Java 8 EnderAydın Orak elron.co
• 2.
  “Every problem incomputer science can be solved by adding another level of indirection.” - David Wheeler
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  Programming Paradigms • MachineCode • Procedural Languages • Object Oriented Languages • Functional Languages • Domain Specific Languages
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  What is FP? In computer science, functional programming is a programming paradigm—a style of building the structure and elements of computer programs—that treats computation as the evaluation of mathematical functions and avoids changing-state and mutable data.
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  Origins • Lambda Calculus(A.Church, 1930s) • Combinatory Logic (H.Curry, 1930s) • LISP (J.McCarthy, 1960s) • ML (1970s) • OCaml (1996) • …
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  FP: Why Now? • Moore’s Law runs out (in terms of CPU speeds) • Increasing need for; • Concurrency & Parallelism • Distributed Computing • Scalability
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  Benefits of FP •Concurrency/Parallelism without tears • Succinct, concise, understandable programming model • Different programming perspective • Reusability, testability • Becoming more accessible
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  Functional Languages • Haskell* • Clean * • Lisp/Scheme • ML/OCaml • F# • Erlang • Java • Scala • C++ (11+) • JavaScript * Pure
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  Sample: Imperative Approach class Player{ String name; int score; Player(..){..} } void declareWinner(Player p) { System.out.println(p.name + “ is the winner! ”); } void winner(Player p1, Player p2) { // Impure if(p1.score > p2.score) declareWinner(p1); else declareWinner(p2); } winner(new Player(“Ram”, 10), new Player(“John”, 20));
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  Sample: Functional Core +Impure Layers class Player { String name; int score; Player(..){..} } void declareWinner(Player p) { System.out.println(p.name + “ is the winner! ”); } Player maxScore(Player p1, Player p2) { return p1.score > p2.score ? p1 : p2; } Player winner(Player p1, Player p2) { declareWinner(maxScore(p1, p2)); } winner(new Player(“Ram”, 10), new Player(“John”, 20));
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  Sample: Reuse List<Player> players =List(Player("Ram", 10), Player("John", 15), Player("Hari", 20), Player("Krishna", 17)); System.out.println(players.stream().reduce(Play::maxScore));
• 12.
  Hands on examples EnderAydın Orak elron.co
• 13.
  Done. (for now) EnderAydın Orak elron.co