Pattern Matching in Ruby ( 2017 RubyKaigi）

This presentation is about the proposal of new feature of Ruby: pattern matching.
It was published at the session of RubyKaigi 2017
http://rubykaigi.org/2017/presentations/yotii23.html

Transcript

1. Pattern Matching in Ruby Yuki Torii, Sep.20.2017
2. Who am I?<Yuki Torii> ❖ a Rails Developer of Everyleaf Corporation. ❖ a Japanese translator of ❖ “Hello Ruby” series
 (By Linda Liucusʣ ❖ “Programing Elixir” 
 (By Dave Thomasʣ corporating with Koich Sasada ❖ a member of Rails Girls in JP
4. The Goal of This Presentation ❖ Main: You want to use Pattern Matching in Ruby ❖ Sub: You know how to extend Ruby by Ruby
5. Agenda ❖ Demo 1 ❖ What is Pattern Matching ❖ The Detail of My Proposal ❖ Demo 2 (details) ❖ Implementation by (almost) Ruby 
 as a Conceptual Model ❖ Future Issues
6. First Demo(in live) Code Result
7. What is Pattern Matching “pattern matching is the act of checking a given sequence of tokens for the presence of the constituents of some pattern.” – WikiPedia Pattern matching
 https://en.wikipedia.org/wiki/Pattern_matching
8. What is Pattern Matching ❖ ex. Ruby’s Regexp is also Pattern Matching 1BUUFSO 4FRVFODF
   PG
 5PLFOT
9. What is Pattern Matching ❖ ex2. Elixir’s Pattern Matching ❖ Elixir is a functional programing language working on Erlang VM. ❖ Elixir’s grammar is influenced by Ruby ❖ It has powerful pattern matching system
10. What is Pattern Matching ❖ In Elixir, `=` is always Pattern Matching, 
 not assigning value
11. What is Pattern Matching ❖ More examples of Elixir
12. What is Pattern Matching ❖ Elixir has guards: more complex check. result#=> < guard clause
13. What is Pattern Matching ❖ Ruby’s Existing Pattern Matching gem “pattern- match”
 https://github.com/k-tsj/pattern-match
14. The detail of my proposal ❖ %p ❖ like %w, %i ❖ `=~` for matching Basic Usage
15. The detail of my proposal ❖ `===` is a alias of `=~`
16. Demo of details
17. demo(with case when statement) Code Result
18. demo(with hash, and _(ignored pattern)) Code Result
19. demo(nested pattern) Code Result
20. demo(with regexp) Code Result
21. demo(with Class of object) Code Result
22. Implementation as a concept model ❖ I wrote almost part of pm by Ruby.
 C-lang diff is only below: ❖ (show parse.y & complile.c diff ) ❖ What trick did I use? compile.c parse.y
23. Implementation as a concept model Ruby script Parse Compile Ruby byte code Evaluator
24. Implementation of the concept model Ruby script Parse Compile Ruby byte code PatternMatching %p([a, 1]) =~ [3, 1] “[a, 1]” variables list [“a”] Define variabies Evaluator pattern_match obj Parse pattern Convert script,
 Generate inspections with the additional code
25. How I implement it as concept model Ruby script Parse Compile Ruby byte code PatternMatching %p([a, 1]) =~ [3, 1] “[a, 1]” variables list Define variabies Evaluator pattern_match obj Parse pattern build AST check matching assign values variables list [“a”] Convert script,
 Generate inspections with the additional code Convert Script ?
26. Implementation of the concept model %p([a, 1]) =~ [3, 1] in Compiling to byte code Convert Script PatternMatch.save_binding(b)
 %p([a, 1]) =~ [3, 1] Ruby byte code save binding build AST check matching assign values build AST check matching assign values
27. Implementation of the concept model ❖ Ruby library ❖ Parse patterns ❖ Matching values ❖ Comparing ❖ Assignment
28. Back to the goals ❖ Main: you want to use Pattern Matching in Ruby ❖ Did it attract you? ❖ Sub: you know How to extend Ruby by Ruby ❖ Now you know the backdoor.
29. Special Thanks ❖ Koichi Sasada ❖ My great adviser of Ruby’s implementation. ❖ Tsujimoto-san ❖ the author of pattern-match gem.
30. Future Issues ❖ Syntax. Is %p the best for making pattern? ❖ Specification of Guard clause ❖ Improve the parser. ❖ https://github.com/yakitorii/pattern-match-ruby