Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
わかる!Java to Clojure
Search
Shunsuke Tadokoro
October 05, 2017
Technology
6
1.7k
わかる!Java to Clojure
2017.10.4「教養としてのClojure」の発表資料です
Shunsuke Tadokoro
October 05, 2017
Tweet
Share
More Decks by Shunsuke Tadokoro
See All by Shunsuke Tadokoro
ある日「Webエンジニアなら、Webサーバーは作れますよね」と言われたら? ~ 3つのJVM言語で作って学ぶ
todokr
2
480
Onboarding Process for Scala Team
todokr
0
1.6k
Running Scala on AWS Lambda in a Snappy Way
todokr
7
4.2k
Scalaでつくる ちょっとしたCLIツール
todokr
0
880
新しいプログラミング言語の学び方 HTTPサーバーを作って学ぶ Java, Scala, Clojure
todokr
28
19k
Scala絵文字ライブラリに Macroなどを導入してみた
todokr
0
1.3k
Clojureに入門してHTTPサーバーをつくってみた話
todokr
3
1k
emojiconに行ってきました
todokr
2
690
Scalaリファクタリング入門「大改造!静的ビフォー・アフター」
todokr
3
1.2k
Other Decks in Technology
See All in Technology
2/18 Making Security Scale: メルカリが考えるセキュリティ戦略 - Coincheck x LayerX x Mercari
jsonf
0
200
エンジニアリング価値を黒字化する バリューベース戦略を用いた 技術戦略策定の道のり
kzkmaeda
6
2.6k
php-conference-nagoya-2025
fuwasegu
0
150
EDRの検知の仕組みと検知回避について
chayakonanaika
11
4.8k
Amazon Q Developerの無料利用枠を使い倒してHello worldを表示させよう!
nrinetcom
PRO
2
110
Visualize, Visualize, Visualize and rclone
tomoaki0705
9
82k
PHPで印刷所に入稿できる名札データを作る / Generating Print-Ready Name Tag Data with PHP
tomzoh
0
180
"TEAM"を導入したら最高のエンジニア"Team"を実現できた / Deploying "TEAM" and Building the Best Engineering "Team"
yuj1osm
1
140
Iceberg Meetup Japan #1 : Iceberg and Databricks
databricksjapan
0
360
大規模アジャイルフレームワークから学ぶエンジニアマネジメントの本質
staka121
PRO
3
1.1k
Autonomous Database Serverless 技術詳細 / adb-s_technical_detail_jp
oracle4engineer
PRO
17
45k
JavaにおけるNull非許容性
skrb
2
2.6k
Featured
See All Featured
Raft: Consensus for Rubyists
vanstee
137
6.8k
Code Review Best Practice
trishagee
67
18k
Responsive Adventures: Dirty Tricks From The Dark Corners of Front-End
smashingmag
251
21k
The MySQL Ecosystem @ GitHub 2015
samlambert
250
12k
It's Worth the Effort
3n
184
28k
Creating an realtime collaboration tool: Agile Flush - .NET Oxford
marcduiker
27
1.9k
Exploring the Power of Turbo Streams & Action Cable | RailsConf2023
kevinliebholz
30
4.6k
Building a Scalable Design System with Sketch
lauravandoore
461
33k
Refactoring Trust on Your Teams (GOTO; Chicago 2020)
rmw
33
2.8k
Building an army of robots
kneath
303
45k
Rails Girls Zürich Keynote
gr2m
94
13k
YesSQL, Process and Tooling at Scale
rocio
172
14k
Transcript
Θ͔Δʂ+BWBUP$MPKVSF ڧཁڭཆͱͯ͠ͷ$MPKVSF EDMK !UPEPLS ָ͘͠
୭ͩ ాॴॣ༎!UPEPLS ීஈ4DBMBΤϯδχΞ ϓϥΠϕʔτͰ$MPKVSF$MPKVSF4DSJQUΛͪΐͪ͜ΐ͜৮Δॳ৺ऀ
None
͓͢͠Δ͜ͱ w 8IZ-JTQ 8IZ$MPKVSF w جຊతͳจ๏ʹ͍ͭͯ w +BWBͷΞϨΛ$MPKVSFͰॻ͍ͯΈΑ͏
8IZ-JTQ w େֶͰ৮͍ͬͯͨͷͰ w ࣄͷͨΊ w ʮܭࢉػϓϩάϥϜͷߏͱղऍʯΛಡΉͨΊ w &NBDTϢʔβʔͩͬͨͷͰ w
+BWB4DSJQU$ͷൽΛ͔Ϳͬͨ-JTQͩͱฉ͍ͯ w ϧϯό͕-JTQͰಈ͍͍ͯΔͱฉ͍ͯ w FUD
None
ϙʔϧɾάϨΞϜ 7JBXFCۀऀ :$PNCJOBUPSઃऀ
-JTQͰྑ͍ϓϩάϥϜ͕ॻ͚ΔͳΒɺ͏͖ͳΜͩɻ ͦ͏Ͱͳ͍ͳΒ͍͍ͬͨԿͷʹཱͭ ϙʔϧɾάϨΞϜ 7JBXFCۀऀ :$PNCJOBUPSઃऀ
ී௨ͷౕΒͷ্Λߦ͚ɻ -JTQͰྑ͍ϓϩάϥϜ͕ॻ͚ΔͳΒɺ͏͖ͳΜͩɻ ͦ͏Ͱͳ͍ͳΒ͍͍ͬͨԿͷʹཱͭ ϙʔϧɾάϨΞϜ 7JBXFCۀऀ :$PNCJOBUPSઃऀ
ී௨ͷౕΒͷ্Λߦ͚ɻ -JTQͰྑ͍ϓϩάϥϜ͕ॻ͚ΔͳΒɺ͏͖ͳΜͩɻ ͦ͏Ͱͳ͍ͳΒ͍͍ͬͨԿͷʹཱͭ ϙʔϧɾάϨΞϜ 7JBXFCۀऀ :$PNCJOBUPSઃऀ :BIPPʹച٫
ී௨ͷౕΒͷ্Λߦ͚ɻ -JTQͰྑ͍ϓϩάϥϜ͕ॻ͚ΔͳΒɺ͏͖ͳΜͩɻ ͦ͏Ͱͳ͍ͳΒ͍͍ͬͨԿͷʹཱͭ ϙʔϧɾάϨΞϜ 7JBXFCۀऀ :$PNCJOBUPSઃऀ Θͨ͠ ී௨ͷϓϩάϥϚ -JTQͰΣϒαʔϏεΛͭ͘Δͱ :BIPPʹԯԁͰങͬͯΒ͑Δʂʂʂ
:BIPPʹച٫
ͳͥ$PNNPO-JTQ4DIFNFͰͳ͘ $MPKVSFʁ
8IZ$MPKVSF w ಡΈ͢͞ w ׅހͷ͕গͳ͍ w ׅހͷछྨ͕ଟ͍ w #FUUFS+BWBͰ͋Δ͜ͱ w
ϦονɾώοΩʔ
8IZ$MPKVSF w ಡΈ͢͞ w ׅހͷ͕গͳ͍ w ׅހͷछྨ͕ଟ͍ w #FUUFS+BWBͰ͋Δ͜ͱ w
ϦονɾώοΩʔ
ಡΈ͢͞ $MPKVSF-JTQͷ౷ΛࣺͯɺಡΈ͢͞ΛͱͬͨʢΒ͍͠ʣ ͦͷͨΊɺ$PNNPO-JTQ4DIFNFʹൺͯ ɾׅހ͕গͳ͍ ɾׅހͷछྨ͕ଟ͍
ಡΈ͢͞ ͨͱ͑ؔͷҾ $PNNPO-JTQ 4DIFNF $MPKVSF (defun square (x) (* x
x)) (define (square x) (* x x)) (defn square [x] (* x x))
ಡΈ͢͞ ͨͱ͑BTTPDJBUJWFͳσʔλߏʢ+BWBͰ͍͏.BQʣ (defparameter greet '(("ja" . "͜Μʹͪ") ("en" . "hello")
("fr" . "bonjour")) (define greet '(("ja" "͜Μʹͪ") ("en" "hello") ("fr" "bonjour")) $PNNPO-JTQ 4DIFNF (def greet {"ja" "͜Μʹͪ" "en" "hello" "fr" "bonjour"}) $MPKVSF
8IZ$MPKVSF w ಡΈ͢͞ w ׅހͷ͕গͳ͍ w ׅހͷछྨ͕ଟ͍ w #FUUFS+BWBͰ͋Δ͜ͱ w
ϦονɾώοΩʔ
8IZ$MPKVSF w ಡΈ͢͞ w ׅހͷ͕গͳ͍ w ׅހͷछྨ͕ଟ͍ w #FUUFS+BWBͰ͋Δ͜ͱ w
ϦονɾώοΩʔ
#FUUFS+BWBͰ͋Δ͜ͱ (.concat "hello" " world") ; -> "hello world" ;;
"hello".concat(" world"); (.getName String) ; -> "java.lang.String" ; String.getName (.. user getAddress getCity) ; -> "Shibuya" ; user.getAddress().getCity(); (.-x (new java.awt.Point 2 3)) ;; 2 ;; -> new java.awt.Point(2, 3).x Math/PI ;; 3.141592653589793 ;; Math.PI +BWBͷ"1*͕ͦͷ··ݺͼग़ͤΔ☕️ ˠ+BWBͰͰ͖Δ͜ͱͰ͖Δʂͱ͍͏҆৺ײ
8IZ$MPKVSF w ಡΈ͢͞ w ׅހͷ͕গͳ͍ w ׅހͷछྨ͕ଟ͍ w #FUUFS+BWBͰ͋Δ͜ͱ w
ϦονɾώοΩʔ
8IZ$MPKVSF w ಡΈ͢͞ w ׅހͷ͕গͳ͍ w ׅހͷछྨ͕ଟ͍ w #FUUFS+BWBͰ͋Δ͜ͱ w
ͳʹΑΓָ͍͠ʂ
ͳʹΑΓָ͍͠ʂ w ߴ֊ؔԆධՁͳͲͷؔܕϓϩάϥϛϯάελΠϧ w ঢ়ଶʹ͍ͭͯͷߟ͑ํɺ*EFOUJUZ 4UBUF 7BMVFͷ w γϯϓϧ͞ʹ͍ͭͯ ͍Ζ͍Ζܹత
IUUQCPYPGQBQFSTIBUFOBCMPHDPNFOUSZTJNQMF@NBEF@FBTZ
ͭ·Γ$MPKVSF ͱ͖͍ͬͭ͢ʂ ֶͼָ͕͍͋ͬͯ͠ʂ
+BWBUP$MPKVSFͯ͠ΈΑ͏ w )FMMPXPSME w ࢛ଇԋࢉ w มએݴ w ؔએݴ w
ແ໊ؔ
खݩͰࢼ͢ͳΒ5SZ$MPKVSF͕͓͢͢Ί w 5SZ$MPKVSF IUUQXXXUSZDMKDPN
·ͣγϯλοΫεʹ׳ΕΑ͏ʂ
-JTQͷγϯλοΫε ׅހͷ࢝·Γ͔ΒऴΘΓ·Ͱ͕୯Ґ (ԿΒ͔ͷॲཧ ॲཧͷରͳͲ…)
͏׳Ε·ͨ͠Ͷ
)FMMPXPSME System.out.println("Hello world"); +BWB $MPKVSF
)FMMPXPSME System.out.println("Hello world"); +BWB (println "Hello world") $MPKVSF
࢛ଇԋࢉ 12 + 40 10 - 1 2 * 3
5 / 2 +BWB $MPKVSF
࢛ଇԋࢉ 12 + 40 10 - 1 2 * 3
5 / 2 +BWB (+ 12 40) (- 10 1) (* 2 3) (/ 5 2) $MPKVSF
࢛ଇԋࢉ 12 + 40 10 - 1 2 * 3
5 / 2 +BWB (+ 12 40) (- 10 1) (* 2 3) (/ 5 2) ; -> 5/2 Λѻ͏Ratioܕ $MPKVSF
˞จࣈྻͷ݁߹TUS จࣈྻͷ݁߹ Ͱͳ͘TUSΛ͏ (+ "hoge" "fuga") ClassCastException java.lang.String cannot be
cast to java.lang.Number clojure.lang.Numbers.add (Numbers.java:128) (str "hoge" "fuga") hogefuga
มએݴ int x = 10; +BWB $MPKVSF
มએݴ int x = 10; +BWB (def x 10) $MPKVSF
มએݴ MFUʹΑΔϩʔΧϧมఆٛʢϩʔΧϧଋറʣΛݟ͔͚Δ΄͏͕ଟ͍ (let [x 10] (+ x 3)) ; xletͷׅހ͚ͩͰࢀরͰ͖Δ
$MPKVSF
ؔએݴ public int f(int x) { return x + 1;
} +BWB $MPKVSF
ؔએݴ public int f(int x) { return x + 1;
} +BWB (defn f [x] (+ x 1)) $MPKVSF
ແ໊ؔ x -> x * 2 +BWB $MPKVSF
ແ໊ؔ x -> x * 2 +BWB (fn [x] (*
x 2)) $MPKVSF
ແ໊ؔ x -> x * 2 +BWB (fn [x] (*
x 2)) #(* % 2) ; ↑ͷ؆ܿͳه๏ $MPKVSF
ແ໊ؔΛͬͯΈΔ Arrays.asList(1, 2, 3).stream() .map(x -> x * 2) .collect(Collectors.toList());
// List(2, 4, 6) +BWB $MPKVSF
ແ໊ؔΛͬͯΈΔ Arrays.asList(1, 2, 3).stream() .map(x -> x * 2) .collect(Collectors.toList());
// List(2, 4, 6) +BWB (map (fn [x] (* x 2)) '(1 2 3)) $MPKVSF
ແ໊ؔΛͬͯΈΔ Arrays.asList(1, 2, 3).stream() .map(x -> x * 2) .collect(Collectors.toList());
// List(2, 4, 6) +BWB (map (fn [x] (* x 2)) '(1 2 3)) (map #(* % 2) '(1 2 3)) $MPKVSF
ͬͱ+BWBUP$MPKVSFͯ͠ΈΑ͏ w γʔέϯεͷจࣈྻ݁߹ w จࣈྻ͕ۭPSۭനจࣈ͔Ͳ͏͔ͷఆ w *OQVU4USFBN͔ΒจࣈྻΛͯ͢ಡΉ
γʔέϯεͷจࣈྻ݁߹
γʔέϯεͷจࣈྻ݁߹ String[] words = { "a", "b", "c" }; StringBuilder
sb = new StringBuilder(); for(String word : words) { sb.append(word); } System.out.println(sb.toString()); // "abc" // Java8 System.out.println(String.join("", words)); +BWBͷ߹
γʔέϯεͷจࣈྻ݁߹ (def words '("a" "b" "c")) (clojure.string/join "" words) ;
͘͠ (apply str words) DMPKVSFͷ߹
γʔέϯεͷจࣈྻ݁߹ (def words '("a" "b" "c")) (clojure.string/join "" words) ;
͘͠ (apply str words) DMPKVSFͷ߹
w ՄมҾΛड͚औΔؔʹγʔέϯεΛ͍ͨ͠ͱ͖ʹ͏ w +BWB4DSJQUͷBQQMZͱҰॹ BQQMZ (str ["a" "b" "c"]) ;
-> ["a" "b" "c"] (apply str ["a" "b" "c"]) ; -> abc ; (str "a" "b" "c") ͱಉ͡
γʔέϯεͷจࣈྻ݁߹ (def words '("a" "b" "c")) (clojure.string/join "" words) ;
͘͠ (apply str words) DMPKVSFͷ߹
จࣈྻ͕ۭPSۭനจࣈ͔Ͳ͏͔ͷఆ
จࣈྻ͕ۭPSۭനจࣈ͔Ͳ͏͔ͷఆ public static boolean isBlank(final CharSequence cs) { int strLen;
if (cs == null || (strLen = cs.length()) == 0) { return true; } for (int i = 0; i < strLen; i++) { if (!Character.isWhitespace(cs.charAt(i))) { return false; } } return true; } isBlank("hello!"); // false isBlank(null); // true isBlank(""); // true isBlank("\r\n\t") // true +BWBͷ߹
จࣈྻ͕ۭPSۭനจࣈ͔Ͳ͏͔ͷఆ (defn blank? [s] (every? #(Character/isWhitespace %) s)) (blank? "helllo!")
; false (blank? nil) ; true (blank? "") ; true (blank? "\n\r\t") ; true DMPKVSFͷ߹
จࣈྻ͕ۭPSۭനจࣈ͔Ͳ͏͔ͷఆ (defn blank? [s] (every? #(Character/isWhitespace %) s)) (blank? "helllo!")
; false (blank? nil) ; true (blank? "") ; true (blank? "\n\r\t") ; true DMPKVSFͷ߹
FWFSZ w ίϨΫγϣϯͷશͯͷཁૉʹରͯ͠ ड़ޠؔʢCPPMFBOΛฦؔ͢ʣΛద༻ w શͯUSVFͳΒUSVF (every? even? '(2 4
6)) ; true (every? even? '(1 2 3)) ; false
จࣈྻ͕ۭPSۭനจࣈ͔Ͳ͏͔ͷఆ (defn blank? [s] (every? #(Character/isWhitespace %) s)) (blank? "helllo!")
; false (blank? nil) ; true (blank? "") ; true (blank? "\n\r\t") ; true DMPKVSFͷ߹
*OQVU4USFBN͔ΒจࣈྻΛͯ͢ಡΉ
*OQVU4USFBN͔ΒจࣈྻΛͯ͢ಡΉ try(BufferedReader reader = new BufferedReader( new InputStreamReader( new FileInputStream("./test.txt"))))
{ StringBuilder sb = new StringBuilder(); String line; while((line = reader.readLine()) != null) { sb.append(line); } System.out.println(sb.toString()); } +BWBͷ߹
*OQVU4USFBN͔ΒจࣈྻΛͯ͢ಡΉ (require [clojure.java.io :as io]) (with-open [bis (io/input-stream "./test.txt")] (println
(slurp bis))) $MPKVSFͷ߹
*OQVU4USFBN͔ΒจࣈྻΛͯ͢ಡΉ (require [clojure.java.io :as io]) (with-open [bis (io/input-stream "./test.txt")] (println
(slurp bis))) $MPKVSFͷ߹
DMPKVSFKBWBJPJOQVUTUSFBN w ҾͰड͚औͬͨ'JMF 63* 63- 4PDLFU CZUFྻ 4USJOHʢͰදݱ͞ΕͨύεʣΛ*OQVU4USFBNʹม w มޙͷ*OQVU4USFBNͷσϑΥϧτ࣮
KBWBJP#VGGFSFE*OQVU4USFBN (require '[clojure.java.io :as io]) (io/input-stream "http://example.com")
XJUIPQFO w +BWBͰ͍͏USZXJUISFTPVSDFߏจɺ 4DBMBͰ͍͏-PBO1BUUFSOΛ࣮ݱ͢Δͷ w XJUIPQFOͰPQFOͨ͠ϦιʔεউखʹDMPTF͞ΕΔ (with-open [in (io/input-stream "./test.txt")]
(do-something in)) ;; already closed!
TMVSQ w 3FBEFS #VGGFSFE3FBEFS *OQVU4USFBN 'JMF 63* 63- 4PDLFU
CZUFྻ DIBSྻΛड͚औΓɺ จࣈྻʹͯ͠ฦ͢ w ରʹͳΔॻ͖ग़͠ͷͨΊͷؔTQJU (spit "./test.txt" "hello I/O!") (println (slurp "./test.txt")) ;; -> hello I/O!
*OQVU4USFBN͔ΒจࣈྻΛͯ͢ಡΉ (require [clojure.java.io :as io]) (with-open [bis (io/input-stream "./test.txt")] (println
(slurp bis))) $MPKVSFͷ߹
*OQVU4USFBN͔ΒจࣈྻΛͯ͢ಡΉ (require [clojure.java.io :as io]) (with-open [bis (io/input-stream "./test.txt")] (println
(slurp bis))) $MPKVSFͷ߹ ;; όοϑΝϦϯάͤͣʹϑΝΠϧ͔ΒಡΉ͚ͩͳΒˣͰOK (println (slurp "./test.txt"))
ࠓ+BWBUP$MPKVSFͨ͠ͷ w )FMMPXPSME w ࢛ଇԋࢉ w มએݴ w ؔએݴ w
ແ໊ؔ w γʔέϯεͷจࣈྻ݁߹ w จࣈྻ͕ۭPSۭനจࣈ͔Ͳ͏͔ͷఆ w *OQVU4USFBN͔ΒจࣈྻΛͯ͢ಡΉ
None