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
Try Cats
Search
fuzyco
January 11, 2018
Technology
0
530
Try Cats
Scalaの関数型ライブラリCatsをやってみた話です。
fuzyco
January 11, 2018
Tweet
Share
More Decks by fuzyco
See All by fuzyco
Functional Error&Retry Handling
hiroki6
2
480
Extensible Effects: beyond the Monad Transformers
hiroki6
1
690
High Performance Scala/high_performance_scala
hiroki6
4
3.9k
並行四方山話/tales_of_concurrency
hiroki6
0
77
Scalaでの並行・並列処理戦略/strategy-for-concurrency-and-parallel-by-scala
hiroki6
9
2.8k
Monad Error with Cats/monad-error-with-cats
hiroki6
0
550
scala_multi_thread.pdf
hiroki6
0
300
GAEを用いたBQ Load戦略/gae_bq_load_strategy
hiroki6
2
1.7k
Extensible Effects with Scala/eff-with-scala
hiroki6
0
950
Other Decks in Technology
See All in Technology
サイバーセキュリティと認知バイアス:対策の隙を埋める心理学的アプローチ
shumei_ito
0
190
いざ、BSC討伐の旅
nikinusu
2
610
"君は見ているが観察していない"で考えるインシデントマネジメント
grimoh
4
1k
LINEヤフー株式会社における音声言語情報処理AI研究開発@SP/SLP研究会 2024.10.22
lycorptech_jp
PRO
2
280
【令和最新版】AWS Direct Connectと愉快なGWたちのおさらい
minorun365
PRO
2
140
マルチモーダルデータ基盤の課題と観点
neonankiti
1
110
FOSS4G 2024 Japan コアデイ 一般発表25 PythonでPLATEAUのデータを手軽に扱ってみる
ra0kley
1
130
信頼性に挑む中で拡張できる・得られる1人のスキルセットとは?
ken5scal
1
400
福岡新卒エンジニアの会
teba_eleven
1
190
AI機能の開発運用のリアルと今後のリアル
akiroom
0
250
スクラムチームを立ち上げる〜チーム開発で得られたもの・得られなかったもの〜
ohnoeight
2
290
Spring Frameworkの新標準!? ~ RestClientとHTTPインターフェース入門 ~
ogiwarat
2
260
Featured
See All Featured
Exploring the Power of Turbo Streams & Action Cable | RailsConf2023
kevinliebholz
27
4.2k
Happy Clients
brianwarren
97
6.7k
Creating an realtime collaboration tool: Agile Flush - .NET Oxford
marcduiker
25
1.8k
Scaling GitHub
holman
458
140k
Code Reviewing Like a Champion
maltzj
520
39k
Cheating the UX When There Is Nothing More to Optimize - PixelPioneers
stephaniewalter
280
13k
Save Time (by Creating Custom Rails Generators)
garrettdimon
PRO
27
820
What's new in Ruby 2.0
geeforr
343
31k
The Cult of Friendly URLs
andyhume
78
6k
Typedesign – Prime Four
hannesfritz
40
2.4k
Producing Creativity
orderedlist
PRO
341
39k
Faster Mobile Websites
deanohume
305
30k
Transcript
5SZ$BUT
ΞδΣϯμ w $BUTͱ w $BUTಠࣗͷϞφυ w $BUTΛ௨ֶͯ͠Μͩ͜ͱ
$BUTͱ 4DBMB[ͷ෦྾ʹΑͬͯੜ·Εͨ ؔܕϓϩάϥϛϯά༻ͷ4DBMBϥΠϒϥϦ ɾࠒੜ ɾʹWϦϦʔε ɾݍ DBUFHPSZ ʹ༝དྷ ಡΜͩจݙ ɾೣ൪IUUQFFETJODPNIFSEJOHDBUTKB
ɾ4DBMB8JUI$BUT
$BUTͷಛ ɾؔܕϓϩάϥϛϯάΛ࣮ݱ͢ΔͨΊͷ ๛ͳܕΫϥεͷఏڙ ɾIBTLFMMʹ͍࣮ۙ &Rɺ4IPXͳͲ
$BUTWT4DBMB[ $BUT ɾ৽͍͠σʔλܕ ɾ࣮༻্ඞཁͳશͯͷ൚༻ؔͷ࣮ ΞυϗοΫଟ૬ੑɺUSBJU JNQMJDJU ೣ൪ΑΓҾ༻ 4DBMB[ ɾ৽͍͠σʔλܕ
ɾඪ४Ϋϥεͷ֦ு 0QUJPO0QT -JTU0QT ɾ࣮༻্ඞཁͳશͯͷ൚༻ؔͷ࣮ ΞυϗοΫଟ૬ੑɺUSBJU JNQMJDJU ಠश4DBMB[ΑΓҾ༻
$BUTWT4DBMB[ &JUIFSa 7BMJEBUFE7BMJEBUJPO 3FBEFS3FBEFS 4UBUF4UBUF 8SJUFS8SJUFS ɾ༻ҙ͞Ε͍ͯΔϝιου͕Ұ෦ҟͳΔ͕ɺ ಉ͡Α͏ͳσʔλܕ͕͋Δ
$BUTಠࣗͷϞφυ ɾ&WBM
&WBMϞφυ ධՁΛ੍ޚ͢Δσʔλܕ import cats.Eval // valͷΑ͏ʹఆٛ࣌ʹධՁ val x = Eval.now
{ println("Computing X") math.random } // Computing X // x: cats.Eval[Double] = Now(0.8724950064732552) // defͷΑ͏ʹৗʹධՁ val y = Eval.always { println("Computing Y") math.random } // y: cats.Eval[Double] = cats.Always@5212e1f5 // lazy valͷΑ͏ʹԆධՁ val z = Eval.later { println("Computing Z") math.random } // z: cats.Eval[Double] = cats.Later@33eda11
&WBMϞφυ ධՁΛ੍ޚ͢Δσʔλܕ x.value // first access // res9: Double =
0.8724950064732552 x.value // second access // res10: Double = 0.8724950064732552 y.value // first access // Computing Y // res11: Double = 0.8795680260041828 y.value // second access // Computing Y // res12: Double = 0.5640213059400854 z.value // first access // Computing Z // res13: Double = 0.5813583535421343 z.value // second access // res14: Double = 0.5813583535421343 import cats.Eval // valͷΑ͏ʹఆٛ࣌ʹධՁ val x = Eval.now { println("Computing X") math.random } // Computing X // x: cats.Eval[Double] = Now(0.8724950064732552) // defͷΑ͏ʹৗʹධՁ val y = Eval.always { println("Computing Y") math.random } // y: cats.Eval[Double] = cats.Always@5212e1f5 // lazy valͷΑ͏ʹԆධՁ val z = Eval.later { println("Computing Z") math.random } // z: cats.Eval[Double] = cats.Later@33eda11
&WBMʹΑΔ࠶ؼॲཧ def factorial(n: BigInt): BigInt = if(n == 1) n
else n * factorial(n - 1) factorial(50000) // ࣮ߦ ඌ࠶ؼͰͳ͍࠶ؼؔ
&WBMʹΑΔ࠶ؼॲཧ def factorial(n: BigInt): BigInt = if(n == 1) n
else n * factorial(n - 1) factorial(50000) // ࣮ߦ ඌ࠶ؼͰͳ͍࠶ؼؔ ελοΫΦʔόʔϑϩʔ͕ى͖Δ factorial(50000) // java.lang.StackOverflowError // ...
&WBMʹΑΔ࠶ؼॲཧ def factorial(n: BigInt): Eval[BigInt] = if(n == 1) {
Eval.now(n) } else { factorial(n - 1).map(_ * n) } factorial(50000).value // ࣮ߦ &WBMΛ༻͍ͨίʔυʹมߋ
&WBMʹΑΔ࠶ؼॲཧ def factorial(n: BigInt): Eval[BigInt] = if(n == 1) {
Eval.now(n) } else { factorial(n - 1).map(_ * n) } factorial(50000).value // ࣮ߦ &WBMΛ༻͍ͨίʔυʹมߋ factorial(50000).value // java.lang.StackOverflowError // ... ελοΫΦʔόʔϑϩʔ͕ى͖Δ
&WBMʹΑΔ࠶ؼॲཧ def factorial(n: BigInt): Eval[BigInt] = if(n == 1) {
Eval.now(n) } else { Eval.defer(factorial(n - 1).map(_ * n)) } factorial(50000).value // ࣮ߦ // res20: BigInt = //33473205095971448369154760940714864779127732…… &WBMEFGFSϝιουΛͬͯ͞ΒʹϦϑΝΫλϦϯά
&WBMʹΑΔ࠶ؼॲཧ def factorial(n: BigInt): Eval[BigInt] = if(n == 1) {
Eval.now(n) } else { Eval.defer(factorial(n - 1).map(_ * n)) } factorial(50000).value // ࣮ߦ // res20: BigInt = //33473205095971448369154760940714864779127732…… factorial(50000).value // res20: BigInt = //33473205095971448369154760940714864779127732…… &WBMEFGFSϝιουΛͬͯ͞ΒʹϦϑΝΫλϦϯά ਖ਼ৗऴྃ
&WBMʹΑΔ࠶ؼॲཧ &WBMEFGFSϝιουԿΛ͍ͯ͠Δͷ͔ʁ def defer[A](a: => Eval[A]): Eval[A] = new Eval.Defer[A](a
_) {} sealed abstract class Defer[A](val thunk: () => Eval[A]) extends Eval[A] { def memoize: Eval[A] = Memoize(this) def value: A = evaluate(this) } &WBM<">Λฦ͢ܭࢉΛԆ͍ͯ͠Δ τϥϯϙϦϯԽ͕ߦΘΕɺ͕ؔचͭͳ͗ ͰݺΕͳ͘ͳΔ
$BUTΛษڧֶͯͯ͠Μͩ͜ͱ ಡΜͩจݙ ɾೣ൪IUUQFFETJODPNIFSEJOHDBUTKB ɾ4DBMB8JUI$BUT ֶͼ ɾϞφυͬͯԿͳͷ͔ ɾ,MFJTMJɺ3FBEFSϞφυ ɾϞφυมࢠ
ϞφυͬͯԿͳͷ͔ Ϟφυͱɺ݁߹ͱಉҰΛຬͨ͢࠷খݶͷ ϞφυίϯϏωʔλͷू·Γͷ͍ͣΕ͔Λ࣮ͨ͠ͷͰ͋Δɻ ΧϥʔίοϓຊΑΓҾ༻
ϞφυͬͯԿͳͷ͔ Ϟφυͱɺ݁߹ͱಉҰΛຬͨ͢࠷খݶͷ ϞφυίϯϏωʔλͷू·Γͷ͍ͣΕ͔Λ࣮ͨ͠ͷͰ͋Δɻ ʁ ΧϥʔίοϓຊΑΓҾ༻
ϞφυͬͯԿͳͷ͔ ϞφυΛඥղ͘Ωʔϫʔυ ɾϑΝϯΫλʔ 'VODUPS ɾΞϓϦΧςΟϒϑΝϯΫλʔ "QQMJDBUJWF'VODUPS ͜ͷೋͭඞͣग़ͯ͘Δ Ϟφυͱɺ݁߹ͱಉҰΛຬͨ͢࠷খݶͷ ϞφυίϯϏωʔλͷू·Γͷ͍ͣΕ͔Λ࣮ͨ͠ͷͰ͋Δɻ
ʁ ΧϥʔίοϓຊΑΓҾ༻
Ϟφυ 'VODUPS"QQMZ "QQMJDBUJWF'VODUPS.POBE DBUTʹ͓͍ͯɺ࣍ͷॱͰਐԽ͍ͯ͘͠
'VODUPS -JTU 0QUJPOͳͲʹରͯ͠ɺ แ·Εͨʹରͯ͠ҾؔΛద༻͢ΔॲཧΛఏڙ͢ΔܕΫϥε List(1, 2, 3).map(_ * 2) //
List(2, 4, 6) Some(1).map(_ * 2) // Some(2) @typeclass trait Functor[F[_]] extends functor.Invariant[F] { self => def map[A, B](fa: F[A])(f: A => B): F[B] .... }
"QQMZ 'VODUPSΛ֦ுͯ͠ɺ/ݸͷ'VODUPSʹ/ҾؔΛ ద༻͢ΔॲཧΛఏڙ͢ΔܕΫϥε import cats.implicits._ // implicit defͰ҉తʹmap2, map3͕ద༻͞ΕΔ (Some(1),
Some(2)).mapN(_ + ) // Some(3) (Some(1), Some(2), Some(3)).mapN(_ * _ * _) // Some(6) (List("ha", "heh", "hmm"), List("?", "!", ".")) mapN {_ + _} // List(ha?, ha!, ha., heh?, heh!, heh., hmm?, hmm!, hmm.)
"QQMJDBUJWF'VODUPS "QQMJDBUJWF"QQMZʹ QVSFϝιου "'<"> ΛՃ͍ͯ͠ΔܕΫϥε ϓϦϛςΟϒΛ"QQMJDBUJWFܕʹมͯ͠ɺ ଞͷ"QQMJDBUJWFͱ߹Ͱ͖Δɹ DBUTͷ7BMJEBUFEBQQMJDBUJWFGVODUPSΛܗ͢Δ 1.pure[Option] //
Some(1) // શͯͷΠϕϯτΛݕূ্ͨ͠Ͱɺ߹Λߦ͏ val result = (valid[String, String]("event 1 ok") |@| invalid[String, String]("event 2 failed!") |@| invalid[String, String]("event 3 failed!")) map {_ + _ + _} // result: cats.data.Validated[String,String] = Invalid(event 2 failed!event 3 failed!) DPNQPTF G QVSF G DPNQPTF QVSF G G QVSFಉҰΛຬͨ͢
.POBE "QQMJDBUJWF'VODUPSෳͷ'VODUPSΛѻ͏͜ͱ͕Ͱ͖͕ͨɺ લͷ'VODUPSʹґଘ͢ΔॲཧΛॻ͚ͳ͍ɻ def hogeOption(a: Int): Option[Int] = Some(a) hogeOption(1).flatMap(a
=> hogeOption(a).map(b => a+b)) // Some(2) for { a <- hogeOption(1) b <- hogeOption(a) } yield (a + b) // Some(2) .POBEલͷʹґଘ͢ΔॲཧΛఏڙ͢ΔܕΫϥε /POFqBU.BQ G qBU.BQ H /POFqBU.BQ BG B qBU.BQ H qBU.BQ݁߹Λຬͨ͢
Ϟφυ·ͱΊ Ϟφυͱɺ݁߹ͱಉҰΛຬͨ͢࠷খݶͷ ϞφυίϯϏωʔλͷू·Γͷ͍ͣΕ͔Λ࣮ͨ͠ͷͰ͋Δɻ DPNQPTF G QVSF G DPNQPTF QVSF G
G ಉҰ /POFqBU.BQ G qBU.BQ H /POFqBU.BQ BG B qBU.BQ H ݁߹ ʹแ·Εͨͷʹରͯ͠ɺؔͷ࿈Λ࣮ߦͰ͖Δ