fertile ground: the roots of clojure

Fertile GroundThe Roots of Clojure

who

1994

C++

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

C++'s strong typing has too many advantages to abandon...– Rich Hickey

Callbacks in C++ Using Template Functors

“ ”

Lisp!

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

● Implementation inheritance

● Hierarchies● Kingdom of Nouns● Mutability● Imperative● Very Verbose Verbosity

eschew

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

“ ”

C++ LispJava

zeitgeist

kingdom of nouns

UtildoThis(...)doThat(...)doSomethingElse(...)toThis(...)

toSomethingElse(...)toThat(...)

fromThis(...)

fromSomethingElse(...)fromThat(...)

asThis(...)

asSomethingElse(...)asThat(...)

copy(...)equals(...)add(...)

rem

ove(

...)

upda

te(..

.)

com

pare

To(..

.)

eat(.

..)

frob

nica

te(.

..)

doThis(...)doThat(...)doSomethingElse(...)toThis(...)

toSomethingElse(...)toThat(...)

fromThis(...)

fromSomethingElse(...)fromThat(...)

asThis(...)

asSomethingElse(...)asThat(...)

copy(...)equals(...)add(...)

remove(...)

update(...)compareTo(...)

eat(...)frobnicate(...)

(ns utils)

String

String cat(String that)

String

String cat(String that)

String

String cat(String that)

String

String cat(String that)

StringWrapper

String cat(String that)

String

Concatenatable

Concatenatable

cat(String this, that)String

Concatenatable

cat(String this, that)String List

cat(List this, that)

Concatenatable

cat(String this, that)String List

cat(List this, that)

String[]

cat(String[] this, that)

Object[][]

cat(Object[][] this, that)

subjectivity

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

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

(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))

(dosync (alter ricky court @lucy))

@rickey

;=> {:in-love? false :likes [:hates-the-show, :smart, :lovely]}

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

(dosync (alter rickey court @lucy))

@rickey

;=> {:in-love? true :likes [:hates-the-show, :smart, :lovely]}

?-

TDD

TDDTEST DRIVEN DENTISTRY

thoughtstuff

TDD

T__

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 9iterate (1+) 0takeWhile (<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]sum [1,2,3,4,5]product [1,2,3,4,5]cycle [1,2,3]repeat 9iterate (1+) 0takeWhile (<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])

laziness

- explosion- non-termination- full-realization

- explosion

- non-termination

- full-realization

windowed

monetDB

- MVCC- Snapshot Isolation

- Transactions

set!

set!

set!

set! set!set!

set!

set!

set!

set!

set!

set!

set!

set!

set!set!set!

set!

set!set!

set!set!

set!

ml

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

-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.

-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.

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

Thread A

(def C (agent 0))

(send-off C inc)

@C%=> 1

Thread B

inc (apply inc @C)

EEK!?

Thanks To● You

● Rich Hickey

● Relevance

● Chris Houser

● Manning Publishing

● The fam

Questions?(example questions below)

● Joel or Mike?● Best zombie movies?● Good writing music?● Parallels between Ornette Coleman

and Clojure?

: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”