わかる！Java to Clojure

2017.10.4「教養としてのClojure」の発表資料です

Transcript

1. Θ͔Δʂ+BWB
   UP
   $MPKVSF 
   ڧཁ
   
   ڭཆͱͯ͠ͷ$MPKVSF
   
   EDMK !UPEPLS ָ͘͠
2. ୭ͩ ాॴ
   ॣ༎
   !UPEPLS
   ීஈ͸4DBMBΤϯδχΞ
   ϓϥΠϕʔτͰ$MPKVSF$MPKVSF4DSJQUΛͪΐͪ͜ΐ͜৮Δॳ৺ऀ
4. ͓࿩͢͠Δ͜ͱ w 8IZ
   -JTQ
   8IZ
   $MPKVSF
   w جຊతͳจ๏ʹ͍ͭͯ
   w +BWBͷΞϨΛ$MPKVSFͰॻ͍ͯΈΑ͏
5. 8IZ
   -JTQ w େֶͰ৮͍ͬͯͨͷͰ
   w ࢓ࣄͷͨΊ
   w ʮܭࢉػϓϩάϥϜͷߏ଄ͱղऍ
   ʯΛಡΉͨΊ
   w &NBDTϢʔβʔͩͬͨͷͰ
   w +BWB4DSJQU͸$ͷൽΛ͔Ϳͬͨ-JTQͩͱฉ͍ͯ
   w ϧϯό͕-JTQͰಈ͍͍ͯΔͱฉ͍ͯ
   w FUD
7. ϙʔϧɾάϨΞϜ
   7JBXFC
   ૑ۀऀ
   :
   $PNCJOBUPS
   ૑ઃऀ
8. -JTQͰྑ͍ϓϩάϥϜ͕ॻ͚ΔͳΒɺ࢖͏΂͖ͳΜͩɻ
   ͦ͏Ͱͳ͍ͳΒ͍͍ͬͨԿͷ໾ʹཱͭ ϙʔϧɾάϨΞϜ
   7JBXFC
   ૑ۀऀ
   :
   $PNCJOBUPS
   ૑ઃऀ
9. ී௨ͷౕΒͷ্Λߦ͚ɻ -JTQͰྑ͍ϓϩάϥϜ͕ॻ͚ΔͳΒɺ࢖͏΂͖ͳΜͩɻ
   ͦ͏Ͱͳ͍ͳΒ͍͍ͬͨԿͷ໾ʹཱͭ ϙʔϧɾάϨΞϜ
   7JBXFC
   ૑ۀऀ
   :
   $PNCJOBUPS
   ૑ઃऀ
10. ී௨ͷౕΒͷ্Λߦ͚ɻ -JTQͰྑ͍ϓϩάϥϜ͕ॻ͚ΔͳΒɺ࢖͏΂͖ͳΜͩɻ
    ͦ͏Ͱͳ͍ͳΒ͍͍ͬͨԿͷ໾ʹཱͭ ϙʔϧɾάϨΞϜ
    7JBXFC
    ૑ۀऀ
    :
    $PNCJOBUPS
    ૑ઃऀ :BIPPʹച٫
11. ී௨ͷౕΒͷ্Λߦ͚ɻ -JTQͰྑ͍ϓϩάϥϜ͕ॻ͚ΔͳΒɺ࢖͏΂͖ͳΜͩɻ
    ͦ͏Ͱͳ͍ͳΒ͍͍ͬͨԿͷ໾ʹཱͭ ϙʔϧɾάϨΞϜ
    7JBXFC
    ૑ۀऀ
    :
    $PNCJOBUPS
    ૑ઃऀ Θͨ͠
    ී௨ͷϓϩάϥϚ -JTQͰ΢ΣϒαʔϏεΛͭ͘Δͱ
    :BIPPʹԯԁͰങͬͯ΋Β͑Δʂʂʂ :BIPPʹച٫
12. ͳͥ$PNNPO
    -JTQ΍4DIFNFͰ͸ͳ͘
 $MPKVSFʁ
13. 8IZ
    $MPKVSF w ಡΈ΍͢͞
    w ׅހͷ਺͕গͳ͍
    w ׅހͷछྨ͕ଟ͍
    w #FUUFS
    +BWBͰ͋Δ͜ͱ
    w ϦονɾώοΩʔ
14. 8IZ
    $MPKVSF w ಡΈ΍͢͞
    w ׅހͷ਺͕গͳ͍
    w ׅހͷछྨ͕ଟ͍
    w #FUUFS
    +BWBͰ͋Δ͜ͱ
    w ϦονɾώοΩʔ
15. ಡΈ΍͢͞ $MPKVSF͸-JTQͷ఻౷ΛࣺͯɺಡΈ΍͢͞ΛͱͬͨʢΒ͍͠ʣ
    ͦͷͨΊɺ$PNNPO
    -JTQ΍4DIFNFʹൺ΂ͯ
    ɾׅހ͕গͳ͍
    ɾׅހͷछྨ͕ଟ͍
16. ಡΈ΍͢͞ ͨͱ͑͹ؔ਺ͷҾ਺ $PNNPO
    -JTQ 4DIFNF $MPKVSF (defun square (x) (* x x)) (define (square x) (* x x)) (defn square [x] (* x x))
17. ಡΈ΍͢͞ ͨͱ͑͹BTTPDJBUJWFͳσʔλߏ଄ʢ+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
18. 8IZ
    $MPKVSF w ಡΈ΍͢͞
    w ׅހͷ਺͕গͳ͍
    w ׅހͷछྨ͕ଟ͍
    w #FUUFS
    +BWBͰ͋Δ͜ͱ
    w ϦονɾώοΩʔ
19. 8IZ
    $MPKVSF w ಡΈ΍͢͞
    w ׅހͷ਺͕গͳ͍
    w ׅހͷछྨ͕ଟ͍
    w #FUUFS
    +BWBͰ͋Δ͜ͱ
    w ϦονɾώοΩʔ
20. #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
    +BWBͰͰ͖Δ͜ͱ͸Ͱ͖Δʂͱ͍͏҆৺ײ
21. 8IZ
    $MPKVSF w ಡΈ΍͢͞
    w ׅހͷ਺͕গͳ͍
    w ׅހͷछྨ͕ଟ͍
    w #FUUFS
    +BWBͰ͋Δ͜ͱ
    w ϦονɾώοΩʔ
22. 8IZ
    $MPKVSF w ಡΈ΍͢͞
    w ׅހͷ਺͕গͳ͍
    w ׅހͷछྨ͕ଟ͍
    w #FUUFS
    +BWBͰ͋Δ͜ͱ
    w ͳʹΑΓָ͍͠ʂ
23. ͳʹΑΓָ͍͠ʂ w ߴ֊ؔ਺΍஗ԆධՁͳͲͷؔ਺ܕϓϩάϥϛϯάελΠϧ
    w ঢ়ଶʹ͍ͭͯͷߟ͑ํɺ*EFOUJUZ
    4UBUF
    7BMVFͷ෼཭
    w γϯϓϧ͞ʹ͍ͭͯ ͍Ζ͍Ζܹࢗత
24. IUUQCPYPGQBQFSTIBUFOBCMPHDPNFOUSZTJNQMF@NBEF@FBTZ
25. ͭ·Γ$MPKVSF͸
 ͱ͖ͬͭ΍͍͢ʂ
 ֶͼָ͕͍͋ͬͯ͠ʂ
26. +BWB
    UP
    $MPKVSFͯ͠ΈΑ͏ w )FMMP
    XPSME
    w ࢛ଇԋࢉ
    w ม਺એݴ
    w ؔ਺એݴ
    w ແ໊ؔ਺
27. खݩͰࢼ͢ͳΒ5SZ
    $MPKVSF͕͓͢͢Ί w 5SZ
    $MPKVSF IUUQXXXUSZDMKDPN
28. ·ͣ͸γϯλοΫεʹ׳ΕΑ͏ʂ
29. -JTQͷγϯλοΫε ׅހͷ࢝·Γ͔ΒऴΘΓ·Ͱ͕୯Ґ (ԿΒ͔ͷॲཧ ॲཧͷର৅ͳͲ…)
30. ΋͏׳Ε·ͨ͠Ͷ
31. )FMMP
    XPSME System.out.println("Hello world"); +BWB $MPKVSF
32. )FMMP
    XPSME System.out.println("Hello world"); +BWB (println "Hello world") $MPKVSF
33. ࢛ଇԋࢉ 12 + 40 10 - 1 2 * 3 5 / 2 +BWB $MPKVSF
34. ࢛ଇԋࢉ 12 + 40 10 - 1 2 * 3 5 / 2 +BWB (+ 12 40) (- 10 1) (* 2 3) (/ 5 2) $MPKVSF
35. ࢛ଇԋࢉ 12 + 40 10 - 1 2 * 3 5 / 2 +BWB (+ 12 40) (- 10 1) (* 2 3) (/ 5 2) ; -> 5/2 ෼਺Λѻ͏Ratioܕ $MPKVSF
36. ˞จࣈྻͷ݁߹͸TUS จࣈྻͷ݁߹͸ Ͱ͸ͳ͘TUSΛ࢖͏ (+ "hoge" "fuga") ClassCastException java.lang.String cannot be cast to java.lang.Number clojure.lang.Numbers.add (Numbers.java:128) (str "hoge" "fuga") hogefuga
37. ม਺એݴ int x = 10; +BWB $MPKVSF
38. ม਺એݴ int x = 10; +BWB (def x 10) $MPKVSF
39. ม਺એݴ MFUʹΑΔϩʔΧϧม਺ఆٛʢϩʔΧϧଋറʣΛݟ͔͚Δ΄͏͕ଟ͍ (let [x 10] (+ x 3)) ; x͸letͷׅހ಺͚ͩͰࢀরͰ͖Δ $MPKVSF
40. ؔ਺એݴ public int f(int x) { return x + 1; } +BWB $MPKVSF
41. ؔ਺એݴ public int f(int x) { return x + 1; } +BWB (defn f [x] (+ x 1)) $MPKVSF
42. ແ໊ؔ਺ x -> x * 2 +BWB $MPKVSF
43. ແ໊ؔ਺ x -> x * 2 +BWB (fn [x] (* x 2)) $MPKVSF
44. ແ໊ؔ਺ x -> x * 2 +BWB (fn [x] (* x 2)) #(* % 2) ; ↑ͷ؆ܿͳه๏ $MPKVSF
45. ແ໊ؔ਺Λ࢖ͬͯΈΔ Arrays.asList(1, 2, 3).stream() .map(x -> x * 2) .collect(Collectors.toList()); // List(2, 4, 6) +BWB $MPKVSF
46. ແ໊ؔ਺Λ࢖ͬͯΈΔ 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
47. ແ໊ؔ਺Λ࢖ͬͯΈΔ 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
48. ΋ͬͱ+BWB
    UP
    $MPKVSFͯ͠ΈΑ͏ w γʔέϯε಺ͷจࣈྻ݁߹
    w จࣈྻ͕ۭ
    PS
    ۭനจࣈ͔Ͳ͏͔ͷ൑ఆ
    w *OQVU4USFBN͔ΒจࣈྻΛ͢΂ͯಡΉ
49. γʔέϯε಺ͷจࣈྻ݁߹
50. γʔέϯε಺ͷจࣈྻ݁߹ 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৔߹
51. γʔέϯε಺ͷจࣈྻ݁߹ (def words '("a" "b" "c")) (clojure.string/join "" words) ; ΋͘͠͸ (apply str words) DMPKVSFͷ৔߹
52. γʔέϯε಺ͷจࣈྻ݁߹ (def words '("a" "b" "c")) (clojure.string/join "" words) ; ΋͘͠͸ (apply str words) DMPKVSFͷ৔߹
53. w Մม௕Ҿ਺Λड͚औΔؔ਺ʹγʔέϯεΛ౉͍ͨ͠ͱ͖ʹ࢖͏
    w +BWB4DSJQUͷBQQMZͱҰॹ BQQMZ (str ["a" "b" "c"]) ; -> ["a" "b" "c"] (apply str ["a" "b" "c"]) ; -> abc ; (str "a" "b" "c") ͱಉ͡
54. γʔέϯε಺ͷจࣈྻ݁߹ (def words '("a" "b" "c")) (clojure.string/join "" words) ; ΋͘͠͸ (apply str words) DMPKVSFͷ৔߹
55. จࣈྻ͕ۭ
    PS
    ۭനจࣈ͔Ͳ͏͔ͷ൑ఆ
56. จࣈྻ͕ۭ
    PS
    ۭനจࣈ͔Ͳ͏͔ͷ൑ఆ 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৔߹
57. จࣈྻ͕ۭ
    PS
    ۭനจࣈ͔Ͳ͏͔ͷ൑ఆ (defn blank? [s] (every? #(Character/isWhitespace %) s)) (blank? "helllo!") ; false (blank? nil) ; true (blank? "") ; true (blank? "\n\r\t") ; true DMPKVSFͷ৔߹
58. จࣈྻ͕ۭ
    PS
    ۭനจࣈ͔Ͳ͏͔ͷ൑ఆ (defn blank? [s] (every? #(Character/isWhitespace %) s)) (blank? "helllo!") ; false (blank? nil) ; true (blank? "") ; true (blank? "\n\r\t") ; true DMPKVSFͷ৔߹
59. FWFSZ w ίϨΫγϣϯͷશͯͷཁૉʹରͯ͠
 ड़ޠؔ਺ʢCPPMFBOΛฦؔ͢਺ʣΛద༻
    w શͯUSVFͳΒUSVF (every? even? '(2 4 6)) ; true (every? even? '(1 2 3)) ; false
60. จࣈྻ͕ۭ
    PS
    ۭനจࣈ͔Ͳ͏͔ͷ൑ఆ (defn blank? [s] (every? #(Character/isWhitespace %) s)) (blank? "helllo!") ; false (blank? nil) ; true (blank? "") ; true (blank? "\n\r\t") ; true DMPKVSFͷ৔߹
61. *OQVU4USFBN͔ΒจࣈྻΛ͢΂ͯಡΉ
62. *OQVU4USFBN͔ΒจࣈྻΛ͢΂ͯಡΉ 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৔߹
63. *OQVU4USFBN͔ΒจࣈྻΛ͢΂ͯಡΉ (require [clojure.java.io :as io]) (with-open [bis (io/input-stream "./test.txt")] (println (slurp bis))) $MPKVSFͷ৔߹
64. *OQVU4USFBN͔ΒจࣈྻΛ͢΂ͯಡΉ (require [clojure.java.io :as io]) (with-open [bis (io/input-stream "./test.txt")] (println (slurp bis))) $MPKVSFͷ৔߹
65. DMPKVSFKBWBJPJOQVUTUSFBN w Ҿ਺Ͱड͚औͬͨ'JMF
    63*
    63-
    4PDLFU
    CZUF഑ྻ΍
 4USJOHʢͰදݱ͞ΕͨύεʣΛ*OQVU4USFBNʹม׵
    w ม׵ޙͷ*OQVU4USFBNͷσϑΥϧτ࣮૷͸

    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    KBWBJP#VGGFSFE*OQVU4USFBN (require '[clojure.java.io :as io]) (io/input-stream "http://example.com")
66. XJUIPQFO w +BWBͰ͍͏USZXJUISFTPVSDFߏจɺ
 4DBMBͰ͍͏-PBO
    1BUUFSOΛ࣮ݱ͢Δ΋ͷ
    w XJUIPQFOͰPQFOͨ͠Ϧιʔε͸উखʹDMPTF͞ΕΔ (with-open [in (io/input-stream "./test.txt")] (do-something in)) ;; already closed!
67. TMVSQ w 3FBEFS
    #VGGFSFE3FBEFS
    *OQVU4USFBN
    'JMF
    63*
    63-
    4PDLFU
    CZUF഑ྻ
    DIBS഑ྻΛड͚औΓɺ
 จࣈྻʹͯ͠ฦ͢
    w ରʹͳΔॻ͖ग़͠ͷͨΊͷؔ਺͸TQJU (spit "./test.txt" "hello I/O!") (println (slurp "./test.txt")) ;; -> hello I/O!
68. *OQVU4USFBN͔ΒจࣈྻΛ͢΂ͯಡΉ (require [clojure.java.io :as io]) (with-open [bis (io/input-stream "./test.txt")] (println (slurp bis))) $MPKVSFͷ৔߹
69. *OQVU4USFBN͔ΒจࣈྻΛ͢΂ͯಡΉ (require [clojure.java.io :as io]) (with-open [bis (io/input-stream "./test.txt")] (println (slurp bis))) $MPKVSFͷ৔߹ ;; όοϑΝϦϯάͤͣʹϑΝΠϧ͔ΒಡΉ͚ͩͳΒˣͰOK (println (slurp "./test.txt"))
70. ࠓ೔+BWB
    UP
    $MPKVSFͨ͠΋ͷ w )FMMP
    XPSME
    w ࢛ଇԋࢉ
    w ม਺એݴ
    w ؔ਺એݴ
    w ແ໊ؔ਺
    w γʔέϯε಺ͷจࣈྻ݁߹
    w จࣈྻ͕ۭ
    PS
    ۭനจࣈ͔Ͳ͏͔ͷ൑ఆ
    w *OQVU4USFBN͔ΒจࣈྻΛ͢΂ͯಡΉ