1. Fertile Ground
The Roots of Clojure

3. who

5. 1994

6. C++

7. C++'s strong typing has too many
advantages to abandon...

8. C++'s strong typing has too many
advantages to abandon...
– Rich Hickey
Callbacks in C++ Using Template Functors
“ ”

13. Lisp!

16. ● Interfaces
● Sub-typing
● Polymorphism
● Encapsulation
● JVM
● Memory model

17. ● Implementation
inheritance
● Hierarchies
● Kingdom of Nouns
● Mutability
● Imperative
● Very Verbose Verbosity

18. eschew

19. We managed to drag a lot of them
about halfway to Lisp.
– Guy L. Steele
“ ”

20. C++ Lisp
Java

22. zeitgeist

24. kingdom
of nouns

25. Util
doThis(...)
doThat(...)
doSomethingElse(...)
toThis(...)
toSomethingElse(...)
toThat(...)
fromThis(...)
fromSomethingElse(...)
fromThat(...)
asThis(...)
asSomethingElse(...)
asThat(...)
copy(...)
equals(...)
add(...)
rem
ove(...)
update(...)
com
pareTo(...)
eat(...)
icate(...)

27. doThis(...)
doThat(...)
doSomethingElse(...)
toThis(...)
toSomethingElse(...)
toThat(...)
fromThis(...)
fromSomethingElse(...)
fromThat(...)
asThis(...)
asSomethingElse(...)
asThat(...)
copy(...)
equals(...)
add(...)
remove(...)
update(...)
compareTo(...)
eat(...)
frobnicate(...)
(ns utils)

28. String
String cat(String that)

29. String
String cat(String that)

30. String
String cat(String that)

31. String
String cat(String that)

32. StringWrapper
String cat(String that)
String

33. Concatenatable

34. Concatenatable
cat(String this, that)
String

35. Concatenatable
cat(String this, that)
String List
cat(List this, that)

36. Concatenatable
cat(String this, that)
String List
cat(List this, that)
String[]
cat(String[] this, that)
Object[][]
cat(Object[][] this, that)

38. subjectivity

39. (def rickey (ref {:in-love? false
:likes [:hates-the-show,
:funny,
:lovely]}))

40. (def lucy (ref {:hates-the-show false,
:funny true,
:lovely true}))

41. (defn match? [m w]
(reduce #(and % %2)
((apply juxt (:likes m))
w)))
(defn court [m w]
(if (match? m w)
(assoc m :in-love? true)
m))

42. (dosync (alter ricky court @lucy))
@rickey
;=> {:in-love? false
:likes [:hates-the-show,
:smart,
:lovely]}

43. (dosync
(ref-set lucy {:hates-the-show true,
:smart true,
:lovely true}))

44. (dosync (alter rickey court @lucy))
@rickey
;=> {:in-love? true
:likes [:hates-the-show,
:smart,
:lovely]}

45. ?-

46. TDD

47. TDDTEST DRIVEN DENTISTRY

48. thoughtstuff

49. TDD

50. T__

52. take 2 [1,2,3,4,5]
drop 2 [1,2,3,4,5]
sum [1,2,3,4,5]
product [1,2,3,4,5]
cycle [1,2,3]
repeat 9
iterate (1+) 0
takeWhile (<3) [1,2,3,4,5]
dropWhile (<3) [1,2,3,4,5]
splitAt 3 [1,2,3,4,5]
any (<5) [1,2,3,4,5]
all even [2,4,6,8]
[x*2 | x <- [0..], x*2 < 9]
zip [1,2,3] [10,11,12]

53. take 2 [1,2,3,4,5]
drop 2 [1,2,3,4,5]
sum [1,2,3,4,5]
product [1,2,3,4,5]
cycle [1,2,3]
repeat 9
iterate (1+) 0
takeWhile (<3) [1,2,3,4,5]
dropWhile (<3) [1,2,3,4,5]
splitAt 3 [1,2,3,4,5]
any (<5) [1,2,3,4,5]
all even [2,4,6,8]
[x*2 | x <- [0..], x*2 < 9]
zip [1,2,3] [10,11,12]
(take 2 [1,2,3,4,5])
(drop 2 [1,2,3,4,5])
(reduce + [1,2,3,4,5])
(reduce * [1,2,3,4,5])
(cycle [1,2,3])
(repeat 9)
(iterate + 0)
(take-while #(< 3) [1,2,3,4,5])
(drop-while #(< 3) [1,2,3,4,5])
(split-at 3 [1,2,3,4,5])
(some #(< 5) [1,2,3,4,5])
(every? even? [2,4,6,8])
(for [x (range) :let [y (* 2 x)]
:while (< y 9)] y)
(map vector [1,2,3] [10,11,12])

54. laziness

55. - explosion
- non-termination
- full-realization

56. - explosion
- non-termination
- full-realization

57. windowed

58. monetDB

60. - MVCC
- Snapshot Isolation
- Transactions

61. set!
set!
set!
set!
set!
set!
set!
set!
set!
set!
set!
set!
set!
set!
set!
set!set!
set!
set!
set!
set!set!

62. set!

63. ml

64. set!
val r = ref 5;
!r;
> val it = 5 : int
r := !r + 4;
!r;
> val it = 9 : int
(def r (ref 5))
@r
;=> 5
(dosync (alter r + 4))
@r
;=> 9

66. -module(counter).
-export([init/0, get/1]).
init() -> spawn(fun() -> loop(0) end).
loop(Value) ->
receive
{get, From} ->
From ! Value,
loop(Value+1)
end.
get(C) ->
C ! {get, self()},
receive X -> X end.

67. -module(counter).
-export([init/0, get/1]).
init() -> spawn(fun() -> loop(0) end).
loop(Value) ->
receive
{get, From} ->
From ! Value,
loop(Value+1)
end.
get(C) ->
C ! {get, self()},
receive X -> X end.
Process B
receive
{get, From} ->
From ! Value,
loop(Value+1)
end.

68. Process B
receive
{get, From} ->
From ! Value,
loop(Value+1)
end.
Process A
c(counter).
C = counter:init().
counter:get(C).
%=> 0
counter:get(C).
%=> 1
get

69. Thread A
(def C (agent 0))
(send-off C inc)
@C
%=> 1
Thread B
inc (apply inc @C)

71. EEK!?

73. Thanks To
● You
● Rich Hickey
● Relevance
● Chris Houser
● Manning Publishing
● The fam

74. Questions?
(example questions below)
● Joel or Mike?
● Best zombie movies?
● Good writing music?
● Parallels between Ornette Coleman
and Clojure?

75. :fred
:ethel
:ricky
:lucy
{:ricky
"lucy",
:fred
"ethel"}
(.toUpper “fred”)
["fred" "ethel"
"lucy"]
{:keys [fred ethel lucy]}
{1 “ethel” 2 “fred”}
(m
:fred)
#{fred ethel lucy}
“Fred”
“Ethel”
“Lucy”
“Ricky”