「関手的データモデル入門 2：統一的に制約を書く方法」をscalaで実装してみた

FunctorialDataModel2.scala

// ネタ元：
// 関手的データモデル入門 2：統一的に制約を書く方法
// http://d.hatena.ne.jp/m-hiyama/20130218/1361145879

//http://www.chimaira.org/img3/funcdata-sample-2.gif
object FunctorialDataModel{
  type Employee = Employee.EmployeeInfo
  type EmployeeNum = Int
  object Employee {
    case class EmployeeInfo(num: Int, office: Office)
    def num: Employee => EmployeeNum = _.num
    def office: Employee => Office = _.office
    //http://www.chimaira.org/img3/funcdata-sample-3.gif
    //officeNum = office;Office.num : Employee→OfficeNum
    //式と同じように書ける
    val officeNum = office andThen Office.num: Employee => OfficeNum
    //http://www.chimaira.org/img3/funcdata-sample-4.gif
    //officeAddr = office;addr : Employee→String
    val officeAddr = office andThen Office.addr: Employee => String
  }

  type Office = Office.OfficeInfo
  type OfficeNum = Int
  object Office {
    case class OfficeInfo(num: Int, chief: Employee, addr: String)
    def num: Office => OfficeNum = _.num
    def chief: Office => Employee = _.chief
    def addr: Office => String = _.addr
    //http://www.chimaira.org/img3/funcdata-sample-3.gif
    //chiefNum = chief;Employee.num : Office→EmployeeNum
    val chiefNum = chief andThen Employee.num: Office => EmployeeNum
    //http://www.chimaira.org/img3/funcdata-sample-6.gif
    //chief;office = idOffice : Office→Office
    val id_Office = chief andThen Employee.office: Office => Office
  }
}