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
   

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2. Why do I Ruby?
   

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3. By learning
   other languages,
   we can broaden
   our horizons and
   also more deeply
   understand
   Ruby.
   — matz
   

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4. !
   

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6. LISP
   

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7. Ruby was a Lisp originally,
   in theory.
   Let's call it MatzLisp from
   now on. ;-)
   — matz
   

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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))
   ;...
   

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13. Functions
    (lambda (x) (* x 2))
    

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14. Functions
    (map
    (lambda (x) (* x 2))
    (1 2 3))
    

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15. Functions
    (map
    (lambda (x) (* x 2))
    (1 2 3))
    [1, 2, 3].map(
    &lambda { |x| x * 2 }
    )
    

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16. Functions
    { |x| x * 2 } # => SyntaxError
    

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17. Functions
    { |x| x * 2 } # => SyntaxError
    def takes_a_block
    yield 2
    end
    takes_a_block { |x| x * 2 } # => 4
    

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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 }
    

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19. Functions
    (describe "my machine" (lambda () (
    (it "produces widgets" (lambda () (
    ;...
    ))))))
    describe "my machine" do
    it "produces widgets" do
    #...
    end
    end
    

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20. Thoughtful inconsistency
    

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21. Syntax
    (
    (let a 1)
    (let b 2)
    (+ a b))
    

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22. The project...was neither
    finalized nor explicitly
    abandoned. It just
    receded into the indefinite
    future...
    — John McCarthy
    

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23. LISP Syntax
    (
    (let a 1)
    (let b 2)
    (+ a b))
    

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24. FORTRAN Syntax
    a = 1
    b = 2
    result = a + b
    

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25. Pick your battles.
    

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26. Ruby parsing/unparsing
    code = "2 + 3 * 4"
    ast = Parser::CurrentRuby.parse(code)
    

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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))), []]
    

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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)"
    

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29. Smalltalk
    

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33. What is "object-oriented
    programming"?
    

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34. What is "object-oriented
    programming"?
    What was the original
    intention of object-
    oriented programming?
    

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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
    

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39. In computer terms,
    Smalltalk is a recursion on
    the notion of computer
    itself.
    — Alan Kay
    

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40. Message passing
    3 + 4
    "=> 7
    

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44. Message passing similarities
    Smalltalk:
    3 perform: '+' asSymbol with: 4
    Ruby:
    3.send(:+, 4)
    

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45. Message passing similarities
    Smalltalk:
    3 isKindOf: Integer
    Ruby:
    3.is_a? Integer
    

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46. Message passing similarities
    Smalltalk:
    Integer isKindOf: Class
    Ruby:
    Integer.is_a? Class
    

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47. Control flow with message sending
    Smalltalk:
    array do: [ :element | Transcript show: element ]
    Ruby:
    array.each { |element| puts element }
    

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48. Metaprogramming
    Integer extend [
    doesNotUnderstand: msg [
    'method not defined' printNl
    ]
    ]
    class Integer
    def method_missing(msg)
    puts 'method not defined'
    end
    end
    

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49. Message passing purity
    (2 + 2 == 5)
    ifTrue: [ Transcript show: 'true'. ]
    ifFalse: [ Transcript show: 'false'. ].
    

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50. Thoughtful inconsistency
    

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53. Pick your battles.
    

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54. Perl
    

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56. "A program is correct if it
    gets the job done before
    you get fired."
    

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57. "There's more than one
    way to do it"
    

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58. "Easy things should be
    easy and hard things
    should be possible"
    

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60. Effortless string interpolation
    $x = 5;
    $msg = "The value is $x now.";
    

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61. More little details
    —native regex syntax
    —%w array syntax
    —heredocs
    —1_000_000 number syntax
    

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62. Globals
    $global_variable = 1
    

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63. Globals
    $$
    

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64. Globals
    $$ # => 19936
    Process ID!
    

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65. Weak typing
    print "8" + "1";
    

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66. Weak typing
    print "8" + "1"; # => 9
    

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67. Weak typing
    @cities = qw( Berlin Tokyo London Boston );
    # Assign the array to a scalar
    $cities_count = @cities;
    

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68. Weak typing
    @cities = qw( Berlin Tokyo London Boston );
    # Assign the array to a scalar
    $cities_count = @cities;
    # => 4
    

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69. Why do I Ruby?
    

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71. Thanks!
    Twitter: @geoffreylitt
    

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