Onboarding Process for Scala Team

ScalaMatsuri 2020 発表資料

Transcript

1. Onboarding Process
   for Scala Team
   ScalaMatsuri 2020
   Scala
   チームのオンボーディング
   1
   

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2. The opinions expressed here are my own and
   do not reflect the view of any organization
   ここで⽰されている⾒解は私個⼈のものであり、いかなる組織の⾒解を反映す
   るものではありません。
   2
   

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3. About this talk
   This talk is for Scala teams welcoming newcomers
   aboard
   Why onboarding matters for Scala teams
   Onboarding practices
   technology knowledge
   business domain knowledge
   Onboarding also refines source code
   新メンバーを迎え⼊れるScala
   チーム向けに、なぜオンボーディングが重要か、
   私たちのプラクティス、オンボーディングがコードを洗練させるということに
   ついてお話しします。 3
   

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4. Background
   This talk is based on experiences in 3 teams
   Team size Newcomers Their Experienced Lang
   3 ~ 5
   2 Mid-careers
   1 Intern
   Java
   10 ~ 15
   3 Mid-careers
   3 Newgrads
   Java, Ruby, Python, JS, Go
   4 ~ 5
   2 Newgrads
   3 Interns
   Java, Python
   このセッションの内容は、3
   つのScala
   チームでの経験を元にしています。
   4
   

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5. Who
   ？
   Shunsuke Tadokoro @todokr
   Software Engineer @ BizReach, Inc.
   Robert Devlin
   Software Engineer @ BizReach, Inc.
   ⽥所 駿佑:
   株式会社ビズリーチ ソフトウェアエンジニア
   ロバート・デブリン:
   株式会社ビズリーチ ソフトウェアエンジニア
   5
   

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7. Scala & Team
   Scala
   とチーム
   7
   

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8. Scala is a "scalable" language
   Unique in its flexibility and expressiveness
   It enables developers and teams to change styles as
   they grow
   Procedural
   Object-Oriented
   Functional
   Scala
   は柔軟で表現⼒の豊かな⾔語。
   開発者やチームの成⻑に合わせてスタイルを変えていくことができる。
   8
   

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9. If the team chooses FP style
   Starts with procedural style...
   まずは⼿続き型のスタイルで始める...
   9
   

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10. If the team chooses FP style...
    As time goes by, the team applies FP style
    そして時は流れ、チームは関数型スタイルに
    10
    

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11. If the team chooses FP style...
    However, it's hard for newcomers
    to catch up with the team
    新メンバーのキャッチアップが⼤変
    11
    

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12. Why catching up matters
    The average half-life for software engineers is 3.2
    years
    「ソフトウェアエンジニアの半減期」は平均で3.2
    年
    12
    

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13. Why catching up matters
    The average half-life for software engineers is 3.2
    years
    We want to minimize the time it takes for newcomers
    to maximize their performance
    新メンバーが最⾼のパフォーマンスを発揮するまでの時間を最⼩にしたい
    13
    

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14. Why catching up matters
    The average half-life for software engineers is 3.2
    years
    We want to minimize the time it takes for newcomers
    to maximize their performance
    Also, we want newcomers to remain with the team
    かつ、新メンバーが⻑く居続けてもらえるようにしたい
    14
    

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15. Employee Onboarding
    従業員オンボーディング
    15
    

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16. Definition: Employee onboarding
    “The process of assisting new hires in gaining a
    functional understanding of the skills and tasks
    required in their new role, helping them to develop new
    relationships with others in the workplace, and
    facilitating an understanding of the company culture
    and goals.”(Dr. Allison Ellis, Ph.D.
    ）
    「新⼊社員が新しい役割に必要なスキルとタスクを機能的に理解し、職場で他
    の⼈と新しい関係を築き、企業⽂化の理解を促進するプロセス」
    16
    

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17. What is employee onboarding good for?
    Productivity
    For a new employee to become fully productive, it takes eight
    months on average (AlliedHR)
    新規採⽤者が最⼤の⽣産性を発揮するまでに必要な期間は平均8
    ヶ⽉
    17
    

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18. What is employee onboarding good for?
    Productivity
    For a new employee to become fully productive, it takes eight
    months on average (AlliedHR)
    A new employee who had a sufficient onboarding programs gain
    full proficiency 34% faster than who didn't (Urbanbound)
    ⼗分なオンボーディングプログラムを受けた従業員は、そうでない従業員に⽐
    べて最⾼のパフォーマンスに達するまでの期間が34%
    短縮される
    18
    

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19. What is employee onboarding good for?
    Productivity
    For a new employee to become fully productive, it takes eight
    months on average (AlliedHR)
    A new employee who had a sufficient onboarding programs gain
    full proficiency 34% faster than who didn't (Urbanbound)
    Retention
    New employees who went through a structured onboarding
    program were 58% more likely to be with the organization after
    three years (Wynhurst Group)
    構造化されたオンボーディングを経験した新規採⽤者は、そうでない採⽤者に
    ⽐べて3
    年後の在職率が58%
    ⾼い
    19
    

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20. What is employee onboarding good for?
    Productivity
    For a new employee to become fully productive, it takes eight
    months on average (AlliedHR)
    A new employee who had a sufficient onboarding programs gain
    full proficiency 34% faster than who didn't (Urbanbound)
    Retention
    New employees who went through a structured onboarding
    program were 58% more likely to be with the organization after
    three years (Wynhurst Group)
    Organizations with a strong onboarding process improve new
    hire retention by 82% (Brandon Hall Group)
    強⼒なオンボーディングプロセスを持つ組織は、新規採⽤者の在職率が82
    ％以
    上向上する
    20
    

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22. What this session focuses
    How to support newcomers to gain a understanding
    of the skills and tasks required in the team using Scala
    このセッションは「新メンバーがScala
    を使うチームに必要なスキルとタスクを
    理解することをどうサポートするか」にフォーカスします。
    22
    

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23. How shall we support?
    A viewpoint: The Professional
    Development Ladder by Steve
    McConnell, the author of the
    Code Complete
    スキルとタスクの理解をどう⽀えるか？
    ひとつの切り⼝が The Professional
    Development Ladder 23
    

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24. The capability for software professional
    “We have found that professional capability for
    software professionals is like a three-legged stool”
    「ソフトウェア開発者のケイパビリティは三本⾜の椅⼦のようなものであるこ
    とが分かった」
    24
    

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25. The capability for software professional
    “We have found that professional capability for
    software professionals is like a three-legged stool”
    1. Technology knowledge
    1.
    テクノロジーの知識
    25
    

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26. The capability for software professional
    “We have found that professional capability for
    software professionals is like a three-legged stool”
    1. Technology knowledge
    2. Business domain knowledge
    2.
    ビジネスドメインの知識
    26
    

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27. The capability for software professional
    “We have found that professional capability for
    software professionals is like a three-legged stool”
    1. Technology knowledge
    2. Business domain knowledge
    3. Software development best practices knowledge
    3.
    ソフトウェア開発のベストプラクティスの知識
    27
    

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28. The capability for software professional
    “We have found that professional capability for
    software professionals is like a three-legged stool”
    1. Technology knowledge
    2. Business domain knowledge
    3. Software development best practices knowledge
    オンボーディングでの問題は、テクノロジーの知識とビジネスドメインの知識
    28
    

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29. Our practice
    in gaining
    Technology Knowledge
    我々のプラクティス:
    テクノロジーの知識編
    29
    

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30. Our practice: Technology Knowledge
    Start from "Why we use Scala"
    Topics we choose
    Types
    Collection operation
    Composition of function
    「なぜScala
    を使うのか」から始める。
    私たちの場合は、「型」「コレクション操作」「関数の合成」。
    30
    

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31. Our practice: Technology Knowledge
    Start from "Why we use Scala"
    Topics we choose
    Types
    Collection operation
    Composition of function
    Patterns
    "Scaffolding" in Mob/Pair programming
    Introduce learning resources
    Quick-win tasks
    その他のオンボーディングでのテクニック。
    モブ/
    ペアでの"Scaffolding"
    、学習リソースの紹介、クイックウィンタスク。
    31
    

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32. Start from "Why we do Scala"
    Scala has many features and patterns. We cannot
    cover all in OJT/Off-JT
    Scala
    にはたくさんの機能とパターンがある。全てをOJT/Off-JT
    でカバーする
    ことはできない。
    32
    

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33. Start from "Why we do Scala"
    Scala has many features and patterns. We cannot
    cover all in OJT/Off-JT
    Therefore, we have to start with "Why we use Scala"
    What value do we see in Scala?
    What aspect affects our business?
    だからこそ「なぜ我々はScala
    を使うのか」から始める。どんな価値を⾒出して
    いるか？どんな性質が⾃分らのビジネスに影響を与えるのか？
    33
    

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34. Start from "Why we do Scala"
    Scala has many features and patterns. We cannot
    cover all in OJT/Off-JT
    Therefore, we have to start with "Why we use Scala"
    What value do we see in Scala?
    What aspect affects our business?
    Then, choose learning topics to concentrate on
    問いへの答えをもとに、⼒を⼊れるトピックを選ぶ
    34
    

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35. Learning topics we highlight
    私たちがハイライトする学習トピック
    35
    

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36. Learning topics we highlight
    Types: How to exploit the power of types
    型:
    その⼒をどう引き出すか
    36
    

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37. Learning topics we highlight
    Types: How to exploit the power of types
    Collections: Understand how the method works
    コレクション:
    メソッドの働きを理解する
    37
    

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38. Learning topics we highlight
    Types: How to exploit the power of types
    Collections: Understand how the method works
    Composition of functions: How to express logic
    cleanly
    関数の合成:
    ロジックをクリーンに表現する
    38
    

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39. Learning topics we highlight
    Types: How to exploit the power of types
    Collections: Understand how the method works
    Composition of functions: How to express logic
    cleanly
    We'll introduce how we unpack these topics.
    これらの学習トピックを、新メンバーにどのようにお話しているかをご紹介し
    ます。
    39
    

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40. Learning topic #1: Types
    トピック1:
    型
    40
    

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41. Type: the set of possible values
    型:
    とりうる値の集合
    41
    

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42. Type: the set of possible values
    val id: String = fetchId(...)
    val name: String = fetchName(...)
    val age: Int = calcAge(...)
    型:
    とりうる値の集合
    42
    

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43. Type: the set of possible values
    val id: String = fetchId(...) // String: ∞
    val name: String = fetchName(...) // String: ∞
    val age: Int = calcAge(...) // Int: -2147483648 ~ 2147483647
    String
    が取りうる値: ∞
    Int
    が取りうる値: -2147483648 ~ 2147483647 43
    

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44. Type: the set of possible values
    val id: String = fetchId(...) // String: ∞
    val name: String = fetchName(...) // String: ∞
    val age: Int = calcAge(...) // Int: -2147483648 ~ 2147483647
    It's very rare to have an unbounded string or integer
    in a real-world domain
    現実の問題領域において、制限のない数値や⽂字列はほぼ存在しない。
    44
    

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45. Type: the set of possible values
    val id: String = fetchId(...) // String: ∞
    val name: String = fetchName(...) // String: ∞
    val age: Int = calcAge(...) // Int: -2147483648 ~ 2147483647
    It's very rare to have an unbounded string or integer
    in a real-world domain
    There's no special meaning or domain-specific
    restriction in String or Int
    String
    やInt
    に特別な意味はない。
    45
    

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46. Exploit the power of types
    型の⼒を引き出す
    46
    

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47. Exploit the power of types
    Value class: not to confuse values
    Value class:
    値を取り違えないようにする
    47
    

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48. Exploit the power of types
    Value class: not to confuse values
    ADT and pattern matching: to express control flow
    simply
    ADT
    とパターンマッチング:
    制御フローをシンプルに表現する
    48
    

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49. Exploit the power of types
    Value class: not to confuse values
    ADT and pattern matching: to express control flow
    simply
    Refinment Type: more type-safety & declarative
    validation
    Refinement Type:
    さらなる型安全性 &
    宣⾔的バリデーション
    49
    

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50. Value class
    Create a more specific, info-rich type and use it
    Not to confuse arguments
    Creating value class takes no labor in Scala
    case class AccountId(value: String) extends AnyVal
    case class AccountName(value: String) extends AnyVal
    val accountId: AccountId = AccountId("@todokr")
    val name: AccountName = AccountName("Shunsuke Tadokoro")
    Value class:
    より特定的で情報量の豊かな型
    50
    

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51. ADT and pattern matching
    An information system is a pack of junctions
    sealed trait IP
    case class IPv4(value: String) extends IP
    case class IPv6(value: String) extends IP
    アプリケーションは分岐の塊
    51
    

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52. ADT and pattern matching
    An information system is a pack of junctions
    sealed trait IP
    case class IPv4(value: String) extends IP
    case class IPv6(value: String) extends IP
    ip match {
    case IPv4(value) => // handle IPv4
    case IPv6(value) => // handle IPv6
    }
    アプリケーションは分岐の塊
    52
    

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53. ADT and pattern matching
    An information system is a pack of junctions
    sealed trait IP
    case class IPv4(value: String) extends IP
    case class IPv6(value: String) extends IP
    ip match {
    case IPv4(value) => // handle IPv4
    case IPv6(value) => // handle IPv6
    }
    The combination of ADT and pattern matching is a
    powerful way to express logic concisely
    ADT
    とパターンマッチングは、簡潔にロジックを表現する強⼒な⼿段
    53
    

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54. Refinement Type
    Handy techniques to harden type safety.
    refined
    A library refining types with type-level predicates
    より型安全性を⾼めるテクニック。refined
    というライブラリで実現。
    54
    

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55. Refinement type with refined
    // Define rule as type
    type AccountIdRule = MinSize[3] And MaxSize[10] And StartsWith["@"]
    type AgeRule = NonNegative
    ルールを型として表現する
    55
    

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56. Refinement type with refined
    // Define rule as type
    type AccountIdRule = MinSize[3] And MaxSize[10] And StartsWith["@"]
    type AgeRule = NonNegative
    // "refine" String and Int type
    type AccountIdString = String Refined AccountIdRule
    type AgeInt = Int Refined AgeRule
    String
    やInt
    を"refine"
    する
    56
    

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57. Refinement type with refined
    // Define rule as type
    type AccountIdRule = MinSize[3] And MaxSize[10] And StartsWith["@"]
    type AgeRule = NonNegative
    // "refine" String and Int type
    type AccountIdString = String Refined AccountIdRule
    type AgeInt = Int Refined AgeRule
    val accountId: AccountIdString = "@uryyyyyyyyy" // Compile error!
    val age: AgeInt = -1 // Compile error!
    ルールを満たさない値はコンパイルエラー
    57
    

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58. More practical example
    https://engineering.visional.inc/blog/168/scala-
    refined-newtype/
    Derive runtime validation logic from type
    Work with Circe & Doobie
    より実践的な例を、弊社エンジニアリングブログで公開しています。
    宣⾔的なランタイムバリデーション、JSON
    やDB
    ライブラリとの連携
    58
    

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59. Newcomer Take: Types
    新メンバーの感想:
    型
    59
    

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60. Newcomer Take: Types
    Types are domain knowledge
    型 =
    ドメイン知識
    60
    

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61. Newcomer Take: Types
    Types are domain knowledge
    Controls expected behavior more closely
    型で、期待する振る舞いを保証できる
    61
    

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62. Learning topic #2: Collections
    トピック2:
    コレクション
    62
    

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63. An application is a pack of collections
    Members
    Products
    Purchases
    Shippings
    ...
    アプリケーションはコレクションの塊
    63
    

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64. Scala has a powerful collection library
    Provides highly abstract operations which are easy-to-
    use, concise and universal.
    Scala
    のコレクションライブラリは強⼒。
    簡潔で広く適⽤できる、⾼度に抽象化された操作。
    64
    

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65. Scala has a powerful collection library
    Provides highly abstract operations which are easy-to-
    use, concise and universal.
    However, teaching what those methods do easily isn't
    easy
    "scala".groupMapReduce(identity)(_ => 1)(_ + _)
    // Map(a -> 2, c -> 1, s -> 1, l -> 1)
    しかし、メソッドの働きを易しく教えるのは簡単ではない
    65
    

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66. Visual Scala Reference
    66
    

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67. View Slide

68. Newcomer Take: Collections
    新メンバーの感想： コレクション
    68
    

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69. Newcomer Take: Collections
    Strictly typed collections enable flexibility
    map/collect/reduce/etc make data processing easy
    型付けされたコレクションが実現する柔軟性
    69
    

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70. Newcomer Take: Collections
    Strictly typed collections enable flexibility
    map/collect/reduce/etc make data processing easy
    Online resources cover this part of Scala well
    オンラインリソースもあります！
    70
    

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71. Learning topic #3: Composing
    functions
    71
    

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72. An application is also a pack of functions
    Composability of functions is important for evolving
    design and keeping it clean.
    アプリケーションは関数の塊。関数の合成のしやすさは、設計の進化とそれを
    クリーンに保つうえで重要
    72
    

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73. An application is also a pack of functions
    Composability of functions is important for evolving
    design and keeping it clean.
    How do we compose functions?
    How do we handle errors?
    関数同⼠をどのように組み合わせるか？
    エラーハンドリングをどうするか？
    73
    

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74. https://fsharpforfunandprofit.com/rop/ 74
    

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75. Composing "one-track" functions is easy
    def add2(n: Int): Int = n + 2
    def multi3(n: Int): Int = n * 3
    multi3(add2(10)) // 36
    val composed = (add2 _).andThen(multi3 _) // or (multi3 _).compose(add2 _)
    composed(10) // 36
    結果が分岐しない "1
    トラック"
    な関数は合成が簡単。
    75
    

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76. "Two-track" function
    However, there are many "two-track" functions in the
    real world
    def validateOrder(order: UnvalidatedOrder): Either[ValidationError, ValidatedOrder]
    def checkStock(order: ValidatedOrder): Either[OutOfStockError, AvailableOrder]
    def priceOrder(order: AvailableOrder): Either[LowerThanMinPriceError, PlacedOrder]
    しかし、現実の世界には "2
    トラック"
    な関数が多くある。
    76
    

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77. How shall we compose two-track
    functions?
    If there is an error, it should get shunted onto the
    failure track and bypass the rest of steps
    失敗時にはその先の関数をバイパスするように合成したい。どうすればよいだ
    ろうか？
    77
    

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78. That's what flatMap is for!
    そのためにあるのが flatMap
    ！
    78
    

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79. Compose two-track functions with flatMap
    def f(order: UnvalidatedOrder): Either[OrderError, PlacedOrder] =
    validateOrder(unvalidatedOrder).flatMap { validatedOrder =>
    checkStock(validatedOrder).flatMap { availableOrder =>
    priceOrder(availableOrder)
    }
    }
    flatMap
    を使って "2
    トラック"
    関数を合成する
    79
    

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80. If all of the functions go ...
    def f(order: UnvalidatedOrder): Either[OrderError, PlacedOrder] =
    validateOrder(order).flatMap { validatedOrder =>
    checkStock(validatedOrder).flatMap { availableOrder =>
    priceOrder(availableOrder) // =>
    }
    }
    すべての関数がうまくいけば...
    80
    

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81. If any function goes ...
    def f(order: UnvalidatedOrder): Either[OrderError, PlacedOrder] =
    validateOrder(order).flatMap { validatedOrder => //
    checkStock(validatedOrder).flatMap { availableOrder =>
    priceOrder(availableOrder)
    }
    }
    validateOrder
    が Left
    なら ...
    81
    

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82. If any function goes ...
    def f(order: UnvalidatedOrder): Either[OrderError, PlacedOrder] =
    validateOrder(order).flatMap { validatedOrder =>
    checkStock(validatedOrder).flatMap { availableOrder => //
    priceOrder(availableOrder)
    }
    }
    checkStock
    が Left
    なら ...
    82
    

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83. If any function goes ...
    def f(order: UnvalidatedOrder): Either[OrderError, PlacedOrder] =
    validateOrder(order).flatMap { validatedOrder =>
    checkStock(validatedOrder).flatMap { availableOrder =>
    priceOrder(availableOrder) //
    }
    }
    priceOrder
    が Left
    なら ...
    83
    

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84. for comprehension
    Is just syntactic sugar to avoid deeply nested code
    def f(order: UnvalidatedOrder): Either[OrderError, PlacedOrder] =
    for {
    validatedOrder <- validateOrder(order)
    availableOrder <- checkStock(validatedOrder)
    placedOrder <- priceOrder(availableOrder)
    } yield placedOrder
    for comprehension
    のシンタックスシュガーで深いネストを避ける
    84
    

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85. Newcomer Take: Composing Functions
    新メンバーの感想： 関数の合成
    85
    

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86. Newcomer Take: Composing Functions
    Cleans error-handling
    エラーハンドリングをきれいに書ける
    86
    

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87. Newcomer Take: Composing Functions
    Cleans error-handling
    Improves readability
    two-track functions make business logic easy to read
    ビジネスロジックが読みやすくなる
    87
    

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88. When we talk about function composition
    The key is .
    not to say the M-word
    コツは こと。
    モ○
    ドって⾔わない
    88
    

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89. When we talk about function composition
    The key is not to say the M-word.
    コツは モ○
    ドって⾔わないこと。
    89
    

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90. Patterns to support gaining
    Technology Knowledge
    テクノロジーの知識習得をサポートするパタン
    90
    

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91. "Scaffolding" in Mob/Pair programming
    Sketch out broad outlines until everyone can realize
    implementation
    Entity, Usecase, Query, Controller, routes, etc.
    ペア/
    モブプログラミングでの "Scaffolding"
    みんなが実装をイメージできるまで、⼤枠をスケッチする
    91
    

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92. Scaffolding
    Sketch a method of usecase layer.
    // in usecase layer
    def placeOrder(order: UnvalidatedOrder): Either[OrderError, PlacedOrder] = {
    // 1. validate order
    // 2. check stocks
    // 3. price order
    ???
    }
    ユースケース層のメソッドをスケッチする。
    92
    

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93. Scaffolding
    Prepare repository/query/entity method interface.
    trait StockRepository {
    /** Validate order
    * ...
    */
    def validate(order: UnvalidatedOrder): Either[InvalidOrderError, ValidatedOrder]
    }
    class JdbcStockRepository extends StockRepository {
    def validate(order: UnvalidatedOrder): Either[InvalidOrderError, ValidatedOrder] = ???
    }
    リポジトリ/
    クエリ/
    エンティティのメソッドのシグネチャを決める。
    93
    

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94. "Scaffolding" in Mob/Pair programming
    Sketch out broad outlines until everyone can realize
    implementation
    Entity, Usecase, Query, Controller, routes, etc.
    ペア/
    モブプログラミングでの "Scaffolding"
    みんなが実装をイメージできるまで、⼤枠をスケッチする。
    94
    

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95. "Scaffolding" in Mob/Pair programming
    Sketch out broad outlines until everyone can realize
    implementation
    Entity, Usecase, Query, Controller, routes, etc.
    Then check the rest of the tasks, replan, and get the
    job done individually
    Implementing a Repository/Query is a good starting point for
    newcomers
    その後に残タスクを確認して計画を修正し、個別に撃破する。
    95
    

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96. "Scaffolding" in Mob/Pair programming
    Sketch out broad outlines until everyone can realize
    implementation
    Entity, Usecase, Query, Controller, routes, etc.
    Then check the rest of the tasks, replan, and get the
    job done individually
    Implementing a Repository/Query is a good starting point for
    newcomers
    Newcomers can;
    Get technical knowledge through practice
    Reduce rework
    新メンバーは⼿戻りを減らしつつ、⼿を動かして学ぶことができる。
    96
    

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97. Newcomer's Take: Scaffolding
    新メンバーの感想： Scaffolding
    97
    

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98. Newcomer's Take: Scaffolding
    Sped up time-to-productivity
    成果を出すまでの時間を縮めることができる。
    98
    

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99. Newcomer's Take: Scaffolding
    Sped up time-to-productivity
    Spread organizational knowledge and best practices
    組織の知識やベストプラクティスを共有できる。
    99
    

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100. Newcomer's Take: Scaffolding
     Sped up time-to-productivity
     Spread organizational knowledge and best practices
     Upfront teaching costs give long-term benefits
     育成コストの前払いで、⻑期的なメリットを得る。
     100
     

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101. Introducing learning resources
     Share learning resources that dig deeper into the
     details individually
     学習リソースの紹介。
     個⼈が詳細を深掘ることができるよう学習リソースを共有する。
     101
     

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102. Introducing learning resources
     Share learning resources that dig deeper into the
     details individually
     Sometimes be sent to newcomers before they join
     the team as an preboarding process
     Preboarding
     の⼀環として、⼊社前のメンバーに送ることもある。
     102
     

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103. Some of the learning resources
     Books
     実践Scala
     ⼊⾨
     Scala Scalable Programming
     Functional Programming in Scala
     Hands-on Scala Programming
     Online Resources
     Scala
     研修テキスト
     Essential Scala
     Scala Exercises
     Essential Slick
     Scala with Cats
     S-99: Ninety-Nine Scala Problems
     Scala Pet Store Step by Step
     Play2 hands-on
     103
     

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104. Essential Scala
     Tour of syntax
     Exercises to implement generic fold,
     Equal type class, etc.
     A good read before reading FP in
     Scala
     Scala with Cats and Essential Slick
     are also recommended
     ⽂法のツアーやジェネリックなfold
     、Equal
     型クラスの実
     装。FP in Scala
     の前にやると丁度いいかも。Scala with
     Cats
     や Essential Slick
     などの姉妹編もおすすめ 104
     

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105. Scala Tutorial (Scala Exercises)
     Based on Coursera course Functional
     Programming Principles in Scala &
     Functional Program Design in Scala
     More than just how-to topics
     Side-effect and time, Functional loop, etc.
     Scala Exercises contains Typelevel's
     lib tutorials, such as Cats, Circe,
     Doobie, and so on
     Coursera
     のコースを元にしている。ただのハウツーでは
     なく、副作⽤や関数型のループなど深い内容。シリーズ
     には他にTypelevel
     のライブラリのチュートリアルも 105
     

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106. Hands-on Scala Programming
     Begins with an explanation of
     grammar, followed by some
     interesting exercises
     Sorting algorithms, file manipulation, JSON
     serialization, etc.
     In the second half, practical lessons
     creating mini-applications
     Web scraping, chatting, and real-time
     synchronization of files, etc.
     ⽂法の解説から始まり、いくつかのエクササイズが続
     く。後半はWeb
     スクレイピングや、リアルタイムファイ
     ル同期などを作る実践的な内容 106
     

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107. Play2 + Slick/ScalikeJdbc
     hands-on
     A tutorial that implements CRUD app
     with Play2 and Slick/ScalikeJdbc
     Amount that can be completed in a
     few hours to a day
     Play2 + Slick/ScalikeJdbc
     でCRUD
     アプリを作るチュート
     リアル。数時間~1
     ⽇で完了できる分量
     107
     

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108. Quick-win tasks
     A pattern that allows newcomers to contribute
     quickly
     クイックウィン タスク。新メンバーがすぐにコードにコントリビュートできる
     ようにするパタン。
     108
     

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109. Quick-win tasks
     A pattern that allows newcomers to contribute
     quickly
     Stock tasks small enough to be done in a few hours ~
     a day
     During the onboarding period, a new member's schedule is likely
     to be shredded. That's why small tasks matter
     数時間~1
     ⽇で完了するタスクを⽇頃からストックしておく。オンボーディング
     期間中はスキマ時間ができがちなので、ほどよく⼩さいサイズが⼤事
     109
     

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110. Quick-win tasks
     A pattern that allows newcomers to contribute
     quickly
     Stock tasks small enough to be done in a few hours ~
     a day
     During the onboarding period, a new member's schedule is likely
     to be shredded. That's why small tasks matter
     For example, updating dependent libraries that Scala
     Steward suggests
     例えば、Scala Steword
     が作ってくれたライブラリアップデートPull Request
     の
     検証など。
     110
     

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111. Our practice
     in instructing
     Business Domain Knowledge
     我々が実践していること:
     ビジネスドメインの知識編
     111
     

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112. Our practice: Business Domain Knowledge
     Classroom-lectures: Market, competitors and our
     product knowledge
     座学:
     市場や競合、⾃プロダクトについての知識を得る
     112
     

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113. Our practice: Business Domain Knowledge
     Classroom-lectures: Market, competitors and our
     product knowledge
     Pair/mob programming: Product specs
     ペアプロやモブプロ： プロダクトの仕様についてのレクチャー
     113
     

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114. Our practice: Business Domain Knowledge
     Classroom-lectures: Market, competitors and our
     product knowledge
     Pair/mob programming: Product specs
     A tool: How domain knowledge is represented in
     source code
     「ドメイン知識がどのようにプロダクトで表現されているか」を可視化するツ
     ール
     114
     

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115. Zugen
     An architecture diagram generator for Scala project
     Provided as a sbt plugin
     Generates diagrams with SemanticDB/ScalaMeta
     Domain object table
     Domain relation diagram
     Method invocation diagram
     Zugen: Scala
     プロジェクトのアーキテクチャ図を⽣成するsbt
     プラグイン
     SemanticDB/ScalaMeta
     で図を⽣成する
     115
     

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116. Target source code example
     package domain.model.order
     sealed trait OrderStatus
     /** Status of an order */
     object OrderStatus {
     /** Placed Status */
     case object Placed extends OrderStatus
     /** Completed Status */
     case object Completed extends OrderStatus
     }
     /** An order */
     case class Order(
     orderId: Id[Order],
     customerId: Id[Customer],
     status: OrderStatus,
     )
     object Order {
     /** Place an order */
     def place(customerId: Id[Customer]): Order = Order(Id("1"), customerId, OrderStatus.Placed)
     }
     対象とするソースコードの例
     116
     

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117. Domain Object Table
     ドメインオブジェクトの⼀覧表
     117
     

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118. Domain Relation Diagram
     ドメインオブジェクトの関連図
     118
     

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119. Method Invocation Diagram
     メソッド呼び出し階層図
     119
     

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120. Onboarding with diagrams
     Diagrams support the understanding of how domain
     knowledge is represented in source code
     As a glossary, a map of bounded context, an overview of usecases
     図はドメインがどのようにコードで表現されているかの理解をサポートする。
     ⽤語集、概念の地図、ユースケースの概観図として。
     120
     

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121. Onboarding with diagrams
     Diagrams support the understanding of how domain
     knowledge is represented in source code
     As a glossary, a map of bounded context, an overview of usecases
     Diagrams make it easier for newcomers to join design
     discussions
     Because newcomers can see the structure, it's easier to say "this
     part can be improved"
     図で、新メンバーがデザインの議論に参加しやすくする。
     構造が⾒えるので「どこそこの形が改善できそう」など発⾔しやすくなる。
     121
     

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122. Onboarding also refines
     source code
     122
     

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123. Realizing design unfit in the onboarding
     process
     While explaining the code to newcomers, we sometimes
     feel uneasy about it
     新メンバーに既存のコードについて説明していると、たまに違和感を覚えるこ
     とがある
     123
     

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124. Realizing design unfit in the onboarding
     process
     While explaining the code to newcomers, we sometimes
     feel uneasy about it
     As the product grows, the team notices the solution
     which the team chose has become insufficient
     "Using regex to parse query params became too complicated..."
     プロダクトが育ち、過去のソリューションでは問題が解けなくなっていること
     に気づく
     124
     

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125. Realizing design unfit in the onboarding
     process
     While explaining the code to newcomers, we sometimes
     feel uneasy about it
     As the product grows, the team notices the solution
     which the team chose has become insufficient
     "Using regex to parse query params became too complicated..."
     Conversely, using "too advanced" solutions to solve
     "everyday" problems
     "Is a finite state machine necessary for this tiny usecase?"
     逆に、過度に⾼度なソリューションで⽇々の問題を解いていることに気づく
     125
     

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126. SoftwareMill Tech Blog "Simple Scala
     Stack"
     As far as Scala is concerned, it’s sometimes easy to
     lose focus on solving simple problems using
     simple code. The Scala language offers a number of
     features (...) This, in turn, can lead to complex code;
     but certainly doesn’t have to. We just need to keep
     in mind, what kind of problem are we solving
     “
     “
     「Scala
     では時として、シンプルな問題をシンプルに解くことへのフォーカスを
     失ってしまいがち」「どんな問題を解いているのかを⼼に留める必要がある」
     126
     

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127. Onboarding process is a great chance
     to find engineering unfit
     Turn randomness into a chance for optimization,
     reconsider styles the team had previously chosen
     オンボーディングはオーバー/
     アンダーエンジニアリングなどのunfit
     を発⾒す
     るチャンス。変化を逆⼿に取り、いままでのスタイルを⾒直す。
     127
     

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128. Not just instruction, but co-creation
     Onboarding process is not a one-way communication,
     but co-creation
     オンボーディングは⼀⽅的な伝達ではなく、共創のプロセス
     128
     

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129. Not just instruction, but co-creation
     Onboarding process is not a one-way communication,
     but co-creation
     Working together with a newcomer to find the best
     style to get 100% of the power of Scala
     Update team's awareness of the challenges
     Review the challenge-solution fit
     Scala
     の⼒を100%
     引き出すために、チームにとって最適なスタイルを新メンバ
     ーといっしょに⾒つける
     129
     

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130. Wrap up
     130
     

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131. Wrap up: Why onboarding matters
     A proper onboarding process reduces lead time to
     newcomers' maximum performance and increases
     retention rate
     This is an important issue for teams adopting Scala because of its
     learning costs
     適切なオンボーディングプロセスは新メンバーのパフォーマンスを発揮するま
     でのリードタイム短縮と離職低下に効く。これは学習コストが⾼いとされる
     Scala
     を採⽤するチームには重要な問題 131
     

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132. Wrap up: Support for gaining knowledge
     There are a lot of topics about gaining technical
     knowledge
     So narrowing the topic down from "Why do we use Scala?" is
     important
     We introduced topics we highlight and techniques
     テクノロジーの知識に関するトピックは沢⼭ある。なので「なぜ我々はScala
     を
     使っているのか？」の問いでトピックを絞り込むことが⼤事
     132
     

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133. Wrap up: Support for gaining knowledge
     There are a lot of topics about gaining technical
     knowledge
     So narrowing the topic down from "Why do we use Scala?" is
     important
     We introduced topics we highlight and techniques
     Gaining business domain knowledge is also important
     Zugen: An architecture diagram generator for Scala project
     ビジネスドメインに関する知識も重要。理解をサポートするツールとして
     Zugen
     を紹介しました
     133
     

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134. Wrap up: Onboarding refines the code
     While using Scala, it’s sometimes easy to lose focus
     on solving simple problems using simple code. We
     need to keep in mind, what problem we are solving
     Scala
     では時として、シンプルな問題をシンプルに解くことへのフォーカスを失
     ってしまいがち。どんな問題を解いているのかを⼼に留める必要がある
     134
     

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135. Wrap up: Onboarding refines the code
     While using Scala, it’s sometimes easy to lose focus
     on solving simple problems using simple code. We
     need to keep in mind, what problem we are solving
     Onboarding process is a great chance to find
     engineering unfit
     オンボーディングは、エンジニアリングのunfit
     を⾒つける絶好のチャンス
     135
     

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136. Wrap up: Onboarding refines the code
     While using Scala, it’s sometimes easy to lose focus
     on solving simple problems using simple code. We
     need to keep in mind, what problem we are solving
     Onboarding process is a great chance to find
     engineering unfit
     In that sense, the onboarding process is not just
     instruction but actually co-creation of the best style
     to utilize 100% of the power of Scala
     その意味で、オンボーディングは⼀⽅的な伝達ではなく、Scala
     の⼒を100%
     引
     き出すベストなスタイルを新メンバーと共に作るプロセス
     136
     

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137. Interested in HR topic like this talk?
     We're looking for Scala developers who are passionate
     about solving people's work-related challenges!
     Feel free to join our Discord channel
     ！
     私たちは⼈が働くことにまつわる課題を解決することに情熱を傾けられるScala
     開発者を探しています。まずはDiscord
     チャンネルでお話しましょう！
     137
     

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138. Thank you!
     Build a nice Scala onboarding process
     Grow your Scala team
     Make Scala community more attractive
     ありがとうございました
     素敵なオンボーディングプロセスを組み⽴てよう、Scala
     チームを育てよう、
     そしてScala
     コミュニティをさらに魅⼒的にしよう 138
     

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