Ruby: A Family History (no notes)

A talk I gave at Railsconf 2018.

Rails is made possible by Ruby’s unique combination of deep dynamism and pragmatic elegance. In turn, Ruby inherited many of its core ideas from older languages including Lisp, Smalltalk, and Perl.

In this talk, we’ll take a tour of these languages and their myriad influences on Ruby, to better understand the foundations of our tools, improve our ability to use them to their full potential, and imagine how they might be further improved.

Transcript

1. Ruby: A Family History Geoffrey Litt @geoffreylitt Panorama Education
2. Why do I Ruby?
3. By learning other languages, we can broaden our horizons and also more deeply understand Ruby. — matz
4. !
6. LISP
7. Ruby was a Lisp originally, in theory. Let's call it MatzLisp from now on. ;-) — matz
9. An interpreter (defun eval (e a) (cond ((atom e) (assoc. e a)) ((atom (car e)) (cond ((eq (car e) 'quote) (cadr e)) ((eq (car e) 'atom) (atom (eval (cadr e) a))) ((eq (car e) 'eq) (eq (eval (cadr e) a) (eval (caddr e) a))) ((eq (car e) 'car) (car (eval (cadr e) a))) ((eq (car e) 'cdr) (cdr (eval (cadr e) a))) ((eq (car e) 'cons) (cons (eval (cadr e) a) (eval (caddr e) a))) ((eq (car e) 'cond) (evcon. (cdr e) a)) ;...
13. Functions (lambda (x) (* x 2))
14. Functions (map (lambda (x) (* x 2)) (1 2 3))
15. Functions (map (lambda (x) (* x 2)) (1 2 3)) [1, 2, 3].map( &lambda { |x| x * 2 } )
16. Functions { |x| x * 2 } # => SyntaxError
17. Functions { |x| x * 2 } # => SyntaxError def takes_a_block yield 2 end takes_a_block { |x| x * 2 } # => 4
18. Functions (remove-if (lambda (n) (< n 4)) (map (lambda (x) (* x 2)) (1 2 3))) [1, 2, 3]. map { |x| x * 2 }. reject{ |n| n < 4 }
19. Functions (describe "my machine" (lambda () ( (it "produces widgets" (lambda () ( ;... )))))) describe "my machine" do it "produces widgets" do #... end end
20. Thoughtful inconsistency
21. Syntax ( (let a 1) (let b 2) (+ a b))
22. The project...was neither finalized nor explicitly abandoned. It just receded into the indefinite future... — John McCarthy
23. LISP Syntax ( (let a 1) (let b 2) (+ a b))
24. FORTRAN Syntax a = 1 b = 2 result = a + b
25. Pick your battles.
26. Ruby parsing/unparsing code = "2 + 3 * 4" ast = Parser::CurrentRuby.parse(code)
27. Ruby parsing/unparsing code = "2 + 3 * 4" ast = Parser::CurrentRuby.parse(code) # => [s(:send, # s(:int, 2), :+, # s(:send, # s(:int, 3), :*, # s(:int, 4))), []]
28. Ruby parsing/unparsing code = "2 + 3 * 4" ast = Parser::CurrentRuby.parse(code) # => [s(:send, # s(:int, 2), :+, # s(:send, # s(:int, 3), :*, # s(:int, 4))), []] 2.1.5 :005 > Unparser.unparse(ast) # => "2 + (3 * 4)"
29. Smalltalk
33. What is "object-oriented programming"?
34. What is "object-oriented programming"? What was the original intention of object- oriented programming?
35. I could hardly believe how beautiful and wonderful the idea of LISP was...but there were deep flaws in its logical foundations. — Alan Kay
39. In computer terms, Smalltalk is a recursion on the notion of computer itself. — Alan Kay
40. Message passing 3 + 4 "=> 7
44. Message passing similarities Smalltalk: 3 perform: '+' asSymbol with: 4 Ruby: 3.send(:+, 4)
45. Message passing similarities Smalltalk: 3 isKindOf: Integer Ruby: 3.is_a? Integer
46. Message passing similarities Smalltalk: Integer isKindOf: Class Ruby: Integer.is_a? Class
47. Control flow with message sending Smalltalk: array do: [ :element | Transcript show: element ] Ruby: array.each { |element| puts element }
48. Metaprogramming Integer extend [ doesNotUnderstand: msg [ 'method not defined' printNl ] ] class Integer def method_missing(msg) puts 'method not defined' end end
49. Message passing purity (2 + 2 == 5) ifTrue: [ Transcript show: 'true'. ] ifFalse: [ Transcript show: 'false'. ].
50. Thoughtful inconsistency
53. Pick your battles.
54. Perl
56. "A program is correct if it gets the job done before you get fired."
57. "There's more than one way to do it"
58. "Easy things should be easy and hard things should be possible"
60. Effortless string interpolation $x = 5; $msg = "The value is $x now.";
61. More little details —native regex syntax —%w array syntax —heredocs —1_000_000 number syntax
62. Globals $global_variable = 1
63. Globals $$
64. Globals $$ # => 19936 Process ID!
65. Weak typing print "8" + "1";
66. Weak typing print "8" + "1"; # => 9
67. Weak typing @cities = qw( Berlin Tokyo London Boston ); # Assign the array to a scalar $cities_count = @cities;
68. Weak typing @cities = qw( Berlin Tokyo London Boston ); # Assign the array to a scalar $cities_count = @cities; # => 4
69. Why do I Ruby?
71. Thanks! Twitter: @geoffreylitt