The advantage of using ’Eff’ in Scala Project

Transcript

1. The advantage of using ’Eff’ in Scala Project Scala Matsuri

   2019 @ma2k8 4DBMBϓϩδΣΫτͰ&⒎Λ࢖༻͢Δར఺

2. About Me ▶Tsubasa Matsukawa - SWE&SRE at Recruit Marketing Partners

   Co.,Ltd. & Quipper Co.,Ltd. @wing_007 ϦΫϧʔτϚʔέςΟϯάύʔτφʔζ݉2VJQQFSॴଐͰ
   48&ͱ43&ྖҬΛ୲౰͍ͯ͠·͢ɻ

3. Our Products ▶Study Sapuri English - English learning app [

   Web/iOS/Android ] ओʹελσΟαϓϦ&OHMJTIͷ։ൃΛ͍ͯ͠·͢ɻ
   ӳޠֶशʹڵຯ͕͋Δํ͸ੋඇ

4. Scala has an elegant syntactic sugar ‘for expression’. To make

   the most of this force…. 4DBMBʹ͸ૉఢͳ౶ҥߏจGPS͕ࣜ͋Γ·͢ɻ
   ͦͷྗΛ࠷େݶར༻͢ΔͨΊʹɾɾɾ

5. We needed to decided which ‘types’ to primarily use to

   when starting Scala projects. ࢲୡ͸4DBMBͷϓϩδΣΫτΛ։࢝͢ΔࡍɺओʹͲͷʮܕʯΛ ࢖༻͢Δͷ͔ΛܾΊΔඞཁ͕͋Γ·͢ɻ

6. These ‘types’ are often chosen. ▶Future[A] ▶Future[Try[A]] ▶Future[E Either A]

   ▶EitherT[Future, E, A] ※There is also case that uses "Task" instead of "Future" ͜ͷΑ͏ͳܕ͕Α͘બ͹ΕΔͰ͠ΐ͏ɻ
   'VUVSFͷ୅ΘΓʹ5BTLΛ࢖͏͜ͱ΋͋Γ·͢

7. Our team is trying…. Eff[R, A] ࢲୡͷνʔϜͰ͸&⒎Λࢼ͍ͯ͠·͢

8. Each pros and cons were…? ͦΕͧΕͷϝϦοτσϝϦοτ͸ʁ

9. Future[A]

10. ▶ Easy ௕ॴ͸؆୯͞ʹਚ͖·͢ɻ Pros of Future[A]

11. Cons of Future[A] ▶ Rough error handling. ▶ Semaphore hard.

    ※Task solve Semaphore problem. ୹ॴ͸ηϚϑΥͷ੍ޚ͕೉͍͠఺ͱɺ
    ΤϥʔϋϯυϦϯά͕େࡶ೺ʹ͔͠ߦ͑ͳ͍఺Ͱ͢ɻ

12. Future[Try[A]] ɹ

13. Pros of Future[Try[A]] ▶ Error handling is possible. ௕ॴ͸ΤϥʔϋϯυϦϯά͕ՄೳʹͳΔ఺Ͱ͢ɻ

14. Cons of Future[Try[A]] ▶ Only throwable can be used ▶

    Syntax is not simple(Coding 'try ~ catch' every time is very troublesome. ୹ॴ͸ΤϥʔϋϯυϦϯάʹ࢖༻Ͱ͖Δܕ͕
    5ISPXBCMFʹݶΔ఺ͱγϯλοΫε͕ෳࡶʹͳΔ఺Ͱ͢ɻ

15. Personally, I often use ‘Try’ when wrapping Java libraries, but

    since I convert to ‘Either’, they do not appear in signatures. ݸਓతʹ͸5SZ͸+BWBϥΠϒϥϦͷ8SBQͰΑ͘࢖͍·͕͢ɺ &JUIFSܕʹม׵͠ɺγάχνϟʹ͸ग़͠·ͤΜɻ

16. Future[E Either A]

17. Pros of Future[E Either A] ▶ Flexible Error handling is

    possible. ▶ E is ADT can be flexible expression. ▶ Every time force error handling. ௕ॴ͸5SZΑΓ΋ॊೈͳΤϥʔϋϯυϦϯά͕
    ՄೳʹͳΔ఺Ͱ͢ɻ

18. Cons of Future[E Either A] ▶ Rough error handling. ▶

    Every time need to match the type even if you don't need error handling. ୹ॴ͸ΤϥʔϋϯυϦϯά͕
    ෆཁͳՕॴͰ΋ܕ߹Θ͕ͤඞཁʹͳΔ఺Ͱ͢ɻ

19. EitherT[Future, E, A]

20. Pros of EitherT[Future, E, A] ▶ Can solve part of

    the complexity of nesting. ௕ॴ͸͋Δఔ౓ωετͯ͠΋
    GPSࣜΛγϯϓϧʹอͯΔ఺Ͱ͢ɻ

21. Cons of EitherT[Future, E, A] ▶ It gets slower as

    types are stacked. ▶ May change results in evaluation order. ▶ Too many lift. ୹ॴ͸཯଎໰୊ɺධՁॱͰ݁Ռ͕มΘΔՄೳੑ͕͋ΓɺϞφυ ελοΫʹ٧Ήܕ͕૿͑Δͱɺܕ߹Θ͕ͤ൥ࡶʹͳΔ఺Ͱ͢ɻ
    

22. Eff[R, A]

23. Pros of Eff[R, A] ▶ ‘Eff’ can solve other ‘types’

    disadvantage. ▶ Simple syntax. ▶ Can simply use various effects. ▶ Can solved performance problem when types are stacked. ▶ A result doesn't change for the order of evaluation. &⒎͸͜Ε·Ͱ঺հͨ͠ܕͷσϝϦοτͷ
    େ෦෼ΛղফͰ͖·͢ɻ

24. Cons of Eff[R, A] ▶’Eff’ is very simple syntax. But

    not easy. ▶ difficult effects wire. ▶ Anything is lazy evaluation. ▶ Complexity of type specification. &⒎ͷσϝϦοτ͸ɺ؆୯Ͱ͸ͳ͍఺Ͱ͢ɻ
    ͋Δఔ౓ͷ׳Ε͸ඞཁͰ͠ΐ͏ɻ

25. Our project used ‘Eff’ on clean architecture. զʑͷϓϩδΣΫτͰ͸ɺ$MFBO"SDIJUFDUVSFͰઃܭ͠ɺ
    Ҿ͖ճ͢ܕʹ&⒎Λ࢖༻͢Δߏ੒Λಋೖ͍ͯ͠·͢ɻ

26. ͜ͷΑ͏ʹෳ਺ͷޮՌΛϑϥοτʹهड़Ͱ͖ΔͷͰɺ
    γϯϓϧʹهड़Ͱ͖͍ͯ·͢ɻ

27. How to use ‘Eff’ &⒎ͷ࢖͍ํ Library: https://github.com/atnos-org/eff

28. Define ADT "%5Λఆٛ͠·͢ɻ

29. Define Smart-constructer "%5Λ&⒎ʹੵΉεϚʔτίϯετϥΫλΛఆٛ͠·͢ɻ

30. ੵΜͩ"%5Λղऍ͢ΔΠϯλϓϦλΛఆٛ͠·͢ɻ Define Interpreter

31. Ready to use ‘Eff’. ͜ΕͰ&⒎Λར༻͢Δ४උ͕Ͱ͖·ͨ͠ɻ

32. &⒎Λར༻ͨ͠ϓϩάϥϜΛॻ͖·͢ɻ Write program!!

33. ΠϯλϓϦλʹ͔͚ͯ&⒎Λ࣮ߦ͠·͢ɻ
    SVO99ͷؔ਺͸ͦΕͧΕJNQMJDJU
    DPOWFSTJPOͰੜ΍ͯ͠·͢ɻ Run program!!

34. ‘Eff’ is Good! &⒎͸͍͍ͧʂʢ঺հهࣄͱίʔυαϯϓϧష͓͖ͬͯ·͢ Introduction article: https://tech.recruit-mp.co.jp/server-side/post-18728/ɹ Code sample: https://github.com/ma2k8/eff-arch-example

35. Thanks! ͋Γ͕ͱ͏͍͟͝·ͨ͠ʂ