The mobile market explodes. I have an idea for this awesome app. It connects people together with their phones in a way nobody's thought of yet. Ok, so I'm going to write three native apps: one in Java, one in Objective-C, another in .Net. I need the same logic on my server, except, well, 64-bit enabled. I need the same validation logic there, oh no! Wait, I need a web version of the app, too? Business logic in the front end? How many times do I need to write this damned thing? This is not why I started programming. I wanted to by a sky pirate! There's got to be a better way… Wait. Hrmm. We could get Phone Gap or maybe use Flex. Ugh. That's sluggish and the app doesn't look right and, crap, I still can't run Flex on the server. Still no dice. If only there was a way to take my business logic with me, to whatever technology I needed… If only I could not decide right now all the technologies I'd ever support...

1. The Case for (Scheme)
Jason Felice
@eraserhd
http://maitria.com/
Monday, May 6, 13

2. A Mobile Platform
Walled Garden
A Proprietor
Monday, May 6, 13

3. A Mobile Platform
Apple
Xcode
Google
Android SDK
Microsoft
Visual Studio
Blackberry ??
RIM
Monday, May 6, 13

4. Teams
Android
iOS
Windows
Web
Back-end
Monday, May 6, 13

5. Platform Teams
Monday, May 6, 13

6. Steering
Monday, May 6, 13

7. Monday, May 6, 13

8. Hrmm...
• One feature at a time.
• Implement on every platform.
• Simultaneously release them all.
Monday, May 6, 13

9. Work on ALL the Apps
Monday, May 6, 13

10. Monday, May 6, 13

11. (Scheme)
Gambit
Kawa
Guile C
JVM
CLR
Javascript
IronScheme
Scheme2Js
Fargo
Spock
Bigloo
Monday, May 6, 13

12. SICP
Monday, May 6, 13

13. Structure
(Scheme)
Native Interface
Native Interface
Native Interface
Native Interface
Native Interface
Monday, May 6, 13

14. Monday, May 6, 13

15. Because

16. we

17. care

18. about

19. beautiful

20. code
we

21. hack

22. with

23. intention
Because

24. we

25. care

26. about

27. geek

28. joy
we

29. encourage

30. geeks

31. to

32. code

33. from

34. the

35. heart
Because

36. we

37. care

38. about

39. what's

40. alive

41. in

42. the

43. people

44. we

45. touch
we

46. speak

47. and

48. listen

49. with

50. courageous

51. curiosity
Because

52. we

53. care

54. about

55. what

56. emerges

57. when

58. we

59. collaborate
we

60. show

61. up

62. with

63. confident

64. humility
maitria.com
Monday, May 6, 13

65. Damn Parentheses!
(let loop ((i 0))
(cond
((= i 10)
#f)
(else
(display i)
(loop (+ i 1)))))
Monday, May 6, 13

66. Damn Parentheses!
if ((self = [super
initWithNibName:[[self class]
description]
bundle:[NSBundle
bundleForClass:[self class]]
])) {
...
}
Monday, May 6, 13

67. Hello,World!
(display Hello, World!)
(newline)
Monday, May 6, 13

68. Hello,World!
(define (say-hello)
(display Hello, World!)
(newline))
(say-hello)
Monday, May 6, 13

69. Hello,World!
(define (say-hello)
(display Hello, World!)
(newline))
(say-hello)
Monday, May 6, 13

70. Hello,World!
(define (say-hello)
(display Hello, World!)
(newline))
(say-hello)
Monday, May 6, 13

71. factorial
5! =
5 * 4 * 3 * 2 * 1
n! =
n * (n - 1) * (n - 2) * ... * 1
Monday, May 6, 13

72. factorial
n! =
{ 1, n=1
n(n-1)!, n1
1! = 1
5! = 5•4!
Monday, May 6, 13

73. Monday, May 6, 13

74. factorial
(define (factorial n)
(if (= n 1)
1
(* n (factorial (- n 1))))
Monday, May 6, 13

75. factorial
(define (factorial n)
(if (= n 1)
1
(* n (factorial (- n 1))))
Monday, May 6, 13

76. factorial
(define (factorial n)
(if (= n 1)
1
(* n (factorial (- n 1))))
Monday, May 6, 13

77. factorial
(define (factorial n)
(if (= n 1)
1
(* n (factorial (- n 1))))
Monday, May 6, 13

78. factorial
(define (factorial n)
(if (= n 1)
1
(* n (factorial (- n 1))))
Monday, May 6, 13

79. Lists
(1 2 3)
Monday, May 6, 13

80. Lists
(1 2 3)
1 2 3
()
Monday, May 6, 13

81. Pairs
(1 . 2)
1
2
Monday, May 6, 13

82. Pairs
(1 . 2)
1
2
car
Monday, May 6, 13

83. Pairs
(1 . 2)
1
2
car
cdr
Monday, May 6, 13

84. Monday, May 6, 13

85. Lists
(1 . (2 . (3 . ())))
1 2 3
()
Monday, May 6, 13

86. Lists
(1 . (2 . (3 . ())))
1 2 3
()
Monday, May 6, 13

87. (1 . (2 . (3 . ())))
Lists
1 2 3
()
Monday, May 6, 13

88. Lists
(1 . (2 . (3 . ())))
1 2 3
()
Monday, May 6, 13

89. Code is Data
(sqrt (+ (* x x) (* y y)))
Monday, May 6, 13

90. Code is Data
(sqrt (+ (* x x) (* y y)))
sqrt
()
+
()
* x x
()
* y y
()
Monday, May 6, 13

91. Data is Code
(define x 7)
(define y 4)
(define x2 (list '* 'x 'x))
(define y2 (list '* 'y 'y))
(define x2+y2 (list '+ x2 y2))
(define hypot (list 'sqrt x2+y2))
(eval hypot) = 8.06225774829855
Monday, May 6, 13

92. Monday, May 6, 13

93. (on (collision (ice-block? b) (ice-hole? h))
(in-succession
(remove-object b)
(simultaneously
(play-sound splunk)
(animate h block-melts-into-ice-hole))
(remove-object h)))
Monday, May 6, 13

94. (animation “helper-slides-south”
(play-frames (1 .. 5) for: 0.3)
(repeat
(play-frames (6 7) for: 0.2)
(play-frames (8 .. 10) for: 0.2))
Monday, May 6, 13

95. Monday, May 6, 13