Keeping ruby reasonable
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These are the slides from my RubyConf 2011 talk: "Keeping Ruby Reasonable". In this talk, I covered how first-class environments are implemented in Ruby, and why that poses a problem for Ruby programmers.
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Keeping ruby reasonable
- 2. Hi there!
- 3. Allow me to introduce myself...
- 4. My name is Joshua Ballanco @manhattanmetric https://github.com/jballanc
- 5. I work for
- 6. I work for
- 7. I am also a MacRuby team member (and I tend to talk about MacRuby a lot)
- 9. rea· son· a· ble adj. /ˈrēz(ə)nəbəl/ • Based on good sense
- 10. rea· son· a· ble adj. /ˈrēz(ə)nəbəl/ • Able to be reasoned about
- 11. A Story
- 12. Ruby Reasoner wanted to write a class:
- 13. Peter Pythonista wanted to “help”:
- 14. So Mr. Reasoner ran the code...
- 17. What is going on?!?
- 18. What is going on?!?
- 19. Ruby, we need to talk...
- 20. 1+1 What does it mean?!?
- 21. 1+1 What does it mean?!? • Math equation?
- 22. 1+1 What does it mean?!? • Math equation? • Program?
- 23. foo = Bar.new(baz.qux) What does it mean?!? • Math equation? • Program?
- 24. foo = Bar.new(baz.qux) What does it mean?!? • Math equation? • Program? • What language?
- 25. foo = Bar.new(baz.qux) What does it mean?!? • Math equation? • Program? • What language? • Tokens? Symbols?
- 26. foo = Bar.new(baz.qux) What does it mean?!? • Math equation? • Program? • What language? • Tokens? Symbols? • Function bindings? Semantics? Value transformations???
- 27. Mind Your Environment!
- 28. Can I get a definition?
- 29. Can I get a definition? Binding
- 30. Can I get a definition? Binding Bindings { (Environment)
- 31. Can I get a definition? Binding Bindings { (Environment) Closure
- 32. Can I get a definition? Binding Bindings { (Environment) Closure First-class Environment
- 33. Motivation
- 34. Motivation I really liked first-class environments when I was first exposed to them... ...At this point I believe that first-class environments are useless at best, and dangerous at worst.
- 35. Design of First-Class Environments Four questions to ask when designing a first- class environment implementation...
- 36. Design of First-Class Environments Should you be able to extract an environment from any closure? 1. Yes 2. No
- 37. Design of First-Class Environments Should you be able to extract an environment from any closure? 1. Yes Ruby’s Choice 2. No
- 38. Design of First-Class Environments Should all bindings in the lexical scope of the closure be captured by the environment? 1. All 2. Only those used 3. Only those explicitly specified
- 39. Design of First-Class Environments Should all bindings in the lexical scope of the closure be captured by the environment? 1. All Ruby’s Choice 2. Only those used 3. Only those explicitly specified
- 40. Design of First-Class Environments Should bindings be live in the environment? 1. All bindings are live and mutable 2. Bindings are live, but read-only 3. Bindings are a snapshot in time 4. User specifies state of each binding
- 41. Design of First-Class Environments Should bindings be live in the environment? 1. All bindings are live and mutable Ruby’s 2. Bindings are live, but read-only Choice 3. Bindings are a snapshot in time 4. User specifies state of each binding
- 42. Design of First-Class Environments What happens if you define a new binding using the environment? 1. New binding shadows old binding 2. Environment is cloned containing new binding 3. Defining new bindings is not allowed
- 43. Design of First-Class Environments What happens if you define a new binding using the environment? Ruby’s 1. New binding shadows old binding Choice 2. Environment is cloned containing new binding 3. Defining new bindings is not allowed
- 44. Design of First-Class Environments “When someone suggests ‘first-class environments’, I assume they want options 1, 1, 1, and 1 ... In this variation, though, the user simply cannot reason about his code.”
- 45. Design of First-Class Environments “When someone suggests ‘first-class environments’, I assume they want options 1, 1, 1, and 1 ... In this variation, though, the user simply cannot reason about his code.” Ruby chooses options 1, 1, 1, and 1 !
- 46. What’s a language to do? R6RS Scheme (http://www.r6rs.org/) • Bindings in the environment must be specified explicitly using a library reference • New bindings cannot be created in the environment
- 47. What’s a language to do? Objective-C doesn’t have first-class environments, but...
- 48. What’s a language to do? Objective-C doesn’t have first-class environments, but... Retained, read-only binding
- 49. What’s a language to do? Objective-C doesn’t have first-class environments, but... Retained, read-only binding Live binding
- 50. What’s a language to do? Objective-C doesn’t have first-class environments, but... Collected! Retained, read-only binding Live binding
- 51. I am but a humble Ruby programmer • How many times have you done this?
- 52. I am but a humble Ruby programmer • How many times have you done this? • ...and thought you were safe?
- 53. I am but a humble Ruby programmer • How many times have you done this? • And later needed to do this?
- 54. I am but a humble Ruby programmer • How many times have you done this? • And later needed to do this?
- 55. I am but a humble Ruby programmer • How many times have you done this? • And later needed to do this? • Is that even reasonable?
- 56. First-class Environments are hard...let’s play a game! Let’s play: Capture the Flag Rules: • You must provide a class • The class must contain a method named “flag” • The class must contain a class constant named “Base” • The “Base” must be a proc object • You may only define one class • You may not require or load other source files in your class
- 57. The only winning move is not to play...
- 58. Blue Team, GO!
- 60. Red Team, GO!
- 62. Red Team WINS! ...but why?
- 63. Send in a spy...
- 66. What did we learn? • Ruby’s first-class environments make it difficult to reason about code (and therefore difficult to optimize) • Ruby does have a restricted version of a first-class environment in the Method class • Re-thinking and formalizing first-class environment semantics could make Ruby faster, unbound methods more useful, and Ruby more reasonable in general
- 67. References • https://github.com/jballanc/reasonable_ruby • http://funcall.blogspot.com/ • http://pinboard.in/u:jballanc/ t:Keeping_Ruby_Reasonable/ Questions?
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