Example of type classes for serialisation

bookSerialisation.scala

// Start writing your ScalaFiddle code here
case class Book(title: String, author: String)

trait ToJson[A] {
  def toJson(a: A): String
}

trait ToXml[A] {
  def toXml(a: A): String
}

object BookInstances {
  
  implicit val bookToJsonInstance = new ToJson[Book] {
    override def toJson(book: Book): String = s"""{"title": "${book.title}", "author": "${book.author}"}"""
  }
  
  implicit val bookToXmlInstance = new ToXml[Book] {
    override def toXml(book: Book): String = s"""
    |  <book>
    |    <title>${book.title}</title>
    |    <author>${book.author}</author>
    |  </book>
    """.stripMargin
  }
  
}

object ToJson {
  def apply[A : ToJson] = implicitly[ToJson[A]]
  object ops {
    def toJson[A : ToJson](a: A) = ToJson[A].toJson(a)
  }
}

object ToXml {
  def apply[A : ToXml] = implicitly[ToXml[A]]
  object ops {
    def toXml[A : ToXml](a: A) = ToXml[A].toXml(a)
  }
}

import ToJson._
import ToJson.ops._
import ToXml._
import ToXml.ops._
import BookInstances._

println(toJson(Book("Hello, World!", "Me")))
println(toXml(Book("Hello, World!", "Me")))

def doSomething[A : ToJson](a: A): String = toJson(a)
println(doSomething(Book("Hello, World!", "Me")))

def doSomethingOther(book: Book): String = toJson(book)
println(doSomethingOther(Book("Hello, World!", "Me")))