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  1. import scala.language.higherKinds
  2. import scala.util.Random
  3.  
  4. object Main {
  5.   case class MyType[A](value: List[A])
  6.  
  7.   trait Functor[F[_]] {
  8.     def map[A, B](fa: F[A])(f: A => B): F[B]
  9.   }
  10.  
  11.   val myFunctor: Functor[MyType] = new Functor[MyType] {
  12.     val random = new Random()
  13.  
  14.     override def map[A, B](fa: MyType[A])(f: A => B): MyType[B] =
  15.       MyType(fa.value.flatMap(a =>
  16.         List.fill(choose)(refine(f(a)).asInstanceOf[B])))
  17.  
  18.     private def choose = random.nextInt(5)
  19.  
  20.     private def refine(x: Any): Any = x match {
  21.       case 5 => 8
  22.       case _ => x
  23.     }
  24.   }
  25.  
  26.   def main(args: Array[String]) {
  27.     val m = myFunctor
  28.  
  29.     val fa = MyType(List(1, 2, 3))
  30.     println(m.map(fa)(i => i + 2))
  31.     println(m.map(fa)(i => i + 2))
  32.     println(m.map(fa)(i => i + 2))
  33.     println(m.map(fa)(i => i + 2))
  34.     println(m.map(fa)(i => i + 2))
  35.     println(m.map(fa)(i => i + 2))
  36.   }
  37. }
  38.  
Success #stdin #stdout 0.37s 322240KB
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Standard input is empty
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MyType(List(3, 3, 3, 8))
MyType(List(3, 3, 4, 4, 4, 8))
MyType(List(3, 3, 3, 3, 4, 8, 8, 8, 8))
MyType(List(3, 3, 4, 8, 8, 8))
MyType(List(3, 3, 3, 3, 4, 8, 8, 8, 8))
MyType(List(3, 8, 8, 8, 8))
https://ideone.com/vN4sQ2
language:
Scala (scala 2.12.8)
created:
8 years ago
visibility:
public

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