The document discusses learning multiple programming languages and technologies within 30 days. It outlines the author's motivation for falling behind in their skills, and describes their method of selecting 13 languages, 5 data stores, 5 web frameworks and 7 other technologies to learn. The author explains using a "fold" or "reduce" pattern to implement concepts like summing and mapping in different languages like CoffeeScript, Lua and Scheme.

1. Around
Hello World
in 30 Days
David Eisinger // @deisinger
DevNation Chicago // May 15, 2010

2. Around “Hello World” in 30 Days
1. The Motivation
2. The Methods
3. The Mindset
4. The Moral

3. Around “Hello World” in 30 Days 1. The Motivation
About Me

4. Around “Hello World” in 30 Days 1. The Motivation
About Me

5. Around “Hello World” in 30 Days 1. The Motivation
About Me

6. Around “Hello World” in 30 Days 1. The Motivation
About Me

7. Around “Hello World” in 30 Days 1. The Motivation
About Me

8. Around “Hello World” in 30 Days 1. The Motivation
About Me

9. Around “Hello World” in 30 Days 1. The Motivation
About Me

10. Around “Hello World” in 30 Days 1. The Motivation
About Me

11. Around “Hello World” in 30 Days 1. The Motivation
Falling behind

12. Around “Hello World” in 30 Days 1. The Motivation
Falling behind

13. Around “Hello World” in 30 Days 1. The Motivation
O NOES
Falling behind

14. Around “Hello World” in 30 Days 1. The Motivation
Not on the job.

15. Around “Hello World” in 30 Days 1. The Motivation
Keeping Up

16. Around “Hello World” in 30 Days 1. The Motivation
The Great
Demotivator

17. Around “Hello World” in 30 Days 1. The Motivation
I love
this town.

18. Around “Hello World” in 30 Days
1. The Motivation
2. The Methods
3. The Mindset
4. The Moral

19. Around “Hello World” in 30 Days 2. The Method
The Project

20. Around “Hello World” in 30 Days 2. The Method
Making the list

21. Around “Hello World” in 30 Days 2. The Method
The List
Cassandra 10. HTML5 20. ooc
1. Chrome Extensions 11. Io 21. Redis
2. Clojure 12. Jekyll 22. Riak
3. CoffeeScript 13. jQTouch 23. Scala
4. CouchDB 14. Lua 24. Scheme
5. CSS3 15. MacRuby 25. Sinatra
6. Django 16. Mercurial 26. Squeak
7. Erlang 17. MongoDB 27. Treetop
8. Go 18. Node.js 28. VIM
9. Haskell 19. OCaml 29. ZSH

22. Around “Hello World” in 30 Days 2. The Method
Thirteen Languages
1. Cassandra 11. HTML5 21. ooc
2. Chrome Extensions 12. Io 22. Redis
3. Clojure 13. Jekyll 23. Riak
4. CoffeeScript 14. jQTouch 24. Scala
5. CouchDB 15. Lua 25. Scheme
6. CSS3 16. MacRuby 26. Sinatra
7. Django 17. Mercurial 27. Squeak
8. Erlang 18. MongoDB 28. Treetop
9. Go 19. Node.js 29. VIM
10. Haskell 20. OCaml 30. ZSH

23. Around “Hello World” in 30 Days 2. The Method
Thirteen Languages
1. Cassandra 11. HTML5 21. ooc
2. Chrome Extensions 12. Io 22. Redis
3. Clojure x 13. Jekyll 23. Riak
4. CoffeeScript 14. jQTouch 24. Scala
5. CouchDB 15. Lua 25. Scheme x
6. CSS3 16. MacRuby 26. Sinatra
7. Django 17. Mercurial 27. Squeak
8. Erlang x 18. MongoDB 28. Treetop
9. Go 19. Node.js 29. VIM
10. Haskell x 20. OCaml x 30. ZSH

24. Around “Hello World” in 30 Days 2. The Method
Five Datastores
1. Cassandra 11. HTML5 21. ooc
2. Chrome Extensions 12. Io 22. Redis
3. Clojure 13. Jekyll 23. Riak
4. CoffeeScript 14. jQTouch 24. Scala
5. CouchDB 15. Lua 25. Scheme
6. CSS3 16. MacRuby 26. Sinatra
7. Django 17. Mercurial 27. Squeak
8. Erlang 18. MongoDB 28. Treetop
9. Go 19. Node.js 29. VIM
10. Haskell 20. OCaml 30. ZSH

25. Around “Hello World” in 30 Days 2. The Method
Five Web Frameworks
1. Cassandra 11. HTML5 21. ooc
2. Chrome Extensions 12. Io 22. Redis
3. Clojure 13. Jekyll 23. Riak
4. CoffeeScript 14. jQTouch 24. Scala
5. CouchDB 15. Lua 25. Scheme
6. CSS3 16. MacRuby 26. Sinatra
7. Django 17. Mercurial 27. Squeak
8. Erlang 18. MongoDB 28. Treetop
9. Go 19. Node.js 29. VIM
10. Haskell 20. OCaml 30. ZSH

26. Around “Hello World” in 30 Days 2. The Method
Seven Others
1. Cassandra 11. HTML5 21. ooc
2. Chrome Extensions 12. Io 22. Redis
3. Clojure 13. Jekyll 23. Riak
4. CoffeeScript 14. jQTouch 24. Scala
5. CouchDB 15. Lua 25. Scheme
6. CSS3 16. MacRuby 26. Sinatra
7. Django 17. Mercurial 27. Squeak
8. Erlang 18. MongoDB 28. Treetop
9. Go 19. Node.js 29. VIM
10. Haskell 20. OCaml 30. ZSH

27. Around “Hello World” in 30 Days 2. The Method
The Hour

28. Around “Hello World” in 30 Days 2. The Method
The Buddy System

29. Around “Hello World” in 30 Days 2. The Method
The Fold

30. Around “Hello World” in 30 Days 2. The Method
The Fold

31. Around “Hello World” in 30 Days 2. The Method
The Fold

32. Around “Hello World” in 30 Days 2. The Method
WTF’s a fold?
# sum an array of numbers
[1, 2, 3, 4, 5].inject {|sum, i| sum + i }
# => 15

33. Around “Hello World” in 30 Days 2. The Method
WTF’s a fold?
# collect an array of squares
[1, 2, 3, 4, 5].inject([]) do |coll, i|
coll + [i * i]
end
# => [1, 4, 9, 16, 25]

34. Around “Hello World” in 30 Days 2. The Method
C0ffeeScript
fold: (values, lambda, init...) ->
if init[0]?
result = init[0]
else
result = values[0]
values = values[1..values.length]
for value in values
result = lambda(result, value)
result

35. Around “Hello World” in 30 Days 2. The Method
C0ffeeScript
sum: (values...) -> fold values,
(a, b) -> a + b
x: sum 1, 2, 3, 4, 5
// x == 15

36. Around “Hello World” in 30 Days 2. The Method
C0ffeeScript
(function(){
var fold;
var __slice = Array.prototype.slice;
fold = function fold(values, lambda) {
var _a, _b, _c, _d, init, result, value;
init = __slice.call(arguments, 2, arguments.length - 0);
if ((typeof (_a = init[0]) !== "undefined" && _a !== null)) {
result = init[0];
} else {
result = values[0];
values = values.slice(1, values.length + 1);
}
...

37. Around “Hello World” in 30 Days 2. The Method
Lua
function fold(values, lambda, init)
index, value = next(values, nil)
if init then
result = init
else
result = value
index, value = next(values, index)
end

38. Around “Hello World” in 30 Days 2. The Method
Lua

39. Around “Hello World” in 30 Days 2. The Method
Lua
while index do
result = lambda(result, value)
index, value = next(values, index)
end
return result
end

40. Around “Hello World” in 30 Days 2. The Method
Lua
function sum(values)
return fold(values, function (a, b)
return a + b end)
end
-- sum the set of numbers
sum({1, 2, 3, 4})

41. Around “Hello World” in 30 Days 2. The Method
Lua
function map(values, lambda)
return fold(values, function (c, i)
c[i] = lambda(i)
return c end,
{})
end
-- get the list of squares
map({1, 2, 3, 4}, function (x)
return x * x end)

42. Around “Hello World” in 30 Days 2. The Method
Scheme
(define fold
(lambda (arr f result)
(cond
((null? arr) result)
(else (fold (cdr arr) f (f result (car arr)))))))

43. Around “Hello World” in 30 Days 2. The Method
Scheme
(define fold
(lambda (arr f . result)
(cond
((and (null? arr) (null? result) `()))
((null? arr) (car result))
((null? result) (fold (cdr arr) f (car arr)))
(else (fold (cdr arr) f (f (car result) (car arr)))))))

44. Around “Hello World” in 30 Days 2. The Method
Scheme
> (fold `(1 2 3 4) (lambda (x y) (+ x y)))
10
> (fold `(1 2 3 4)
(lambda (squares x) (cons (* x x) squares)) `())
(16 9 4 1)

45. Around “Hello World” in 30 Days 2. The Method
Erlang
-module(fold).
-export([fold/2, fold/3]).
fold([First | Rest], Fun, Result) ->
fold(Rest, Fun, Fun(Result, First));
fold([], Fun, Result) ->
Result.

46. Around “Hello World” in 30 Days 2. The Method
Erlang

47. Around “Hello World” in 30 Days 2. The Method
Erlang
fold([First | Rest], Fun) ->
fold(Rest, Fun, First);
fold([], Fun) ->
[].
% > fold:fold([1,2,3], fun(Sum, Item) ->
Sum + Item end).
% 6

48. Around “Hello World” in 30 Days 2. The Method
The
Blog

49. Around “Hello World” in 30 Days
1. The Motivation
2. The Methods
3. The Mindset
4. The Moral

50. Around “Hello World” in 30 Days 3. The Mindset
Mastery

51. Around “Hello World” in 30 Days 3. The Mindset
Flow

52. Around “Hello World” in 30 Days 3. The Mindset

53. Around “Hello World” in 30 Days 3. The Mindset
Grit

54. Around “Hello World” in 30 Days 3. The Mindset
Intelligence
(Incremental vs. Entity)

55. Around “Hello World” in 30 Days 3. The Mindset
Hard Work

56. Around “Hello World” in 30 Days
1. The Motivation
2. The Methods
3. The Mindset
4. The Moral

57. Around “Hello World” in 30 Days 4. The Moral
Biggest Surprise:

58. Around “Hello World” in 30 Days 4. The Moral
Biggest Surprise:
CoffeeScript

59. Around “Hello World” in 30 Days 4. The Moral
Biggest Disappointment:

60. Around “Hello World” in 30 Days 4. The Moral
Biggest Disappointment:
CouchDB

61. Around “Hello World” in 30 Days 4. The Moral
Biggest Success:

62. Around “Hello World” in 30 Days 4. The Moral
Biggest Success:
Erlang

63. Around “Hello World” in 30 Days 4. The Moral
Most Value:

64. Around “Hello World” in 30 Days 4. The Moral
Most Value:
Redis

65. Around “Hello World” in 30 Days 4. The Moral
Best Docs:

66. Around “Hello World” in 30 Days 4. The Moral
Best Docs:
Sinatra

67. Around “Hello World” in 30 Days 4. The Moral

68. Around “Hello World” in 30 Days 4. The Moral
Most Bewildering:

69. Around “Hello World” in 30 Days 4. The Moral
Most Bewildering:
Cassandra

70. Around “Hello World” in 30 Days 4. The Moral
Most Fun:

71. Around “Hello World” in 30 Days 4. The Moral
Most Fun:
Scheme

72. Around “Hello World” in 30 Days 4. The Moral
Start Small

73. Around “Hello World” in 30 Days 4. The Moral
Start Now

74. Around “Hello World” in 30 Days 4. The Moral
What was missing?

75. Around “Hello World” in 30 Days 4. The Moral
What was missing?

76. Around “Hello World” in 30 Days 4. The Moral
What was missing?

77. Around “Hello World” in 30 Days 4. The Moral
What was missing?

78. Around “Hello World” in 30 Days 4. The Moral
What was missing?

79. Around “Hello World” in 30 Days 4. The Moral
What was missing?

80. Around “Hello World” in 30 Days 4. The Moral
What was missing?
Strongly-typed
languages are
hard.

81. Around “Hello World” in 30 Days 4. The Moral
Make (& Take) The Time

82. Around “Hello World” in 30 Days 4. The Moral
Stick It Out

83. Around “Hello World” in 30 Days 4. The Moral
Cut & Run

84. Around “Hello World” in 30 Days 4. The Moral
Share Your Experiences

85. Around “Hello World” in 30 Days 4. The Moral
Make
Programming
Play

86. Around “Hello World” in 30 Days
Thanks!
http://speakerrate.com/talks/3249
@deisinger