Render

Render type-class

It is to provider render functionality to render a given type A into String.

trait Render[A] {
  def render(a: A): String
}

Usage Example

import extras.render.Render

final case class Foo(id: Int, name: String)
object Foo {
  implicit val fooRender: Render[Foo] = new Render[Foo] {
    def render(foo: Foo): String =
      s"ID=${foo.id.toString} / Name=${foo.name}"
  }
//  OR just
//  implicit val fooRender: Render[Foo] =
//    foo => s"ID=${foo.id.toString} / Name=${foo.name}"
}

def bar[A: Render](a: A): Unit =
  println(s">> a: ${Render[A].render(a)}")


bar(Foo(1, "Something"))
// >> a: ID=1 / Name=Something

Render.render constructor method

Render.render[A](A => String): Render[A]

Usage Example

import extras.render.Render

final case class Foo(id: Int, name: String)
object Foo {
  implicit val fooRender: Render[Foo] = Render.render(
    foo => s"ID=${foo.id.toString} / Name=${foo.name}"
  )
}

def bar[A: Render](a: A): Unit =
  println(s">> a: ${Render[A].render(a)}")


bar(Foo(1, "Something"))
// >> a: ID=1 / Name=Something

Render from Existing Render

If the value of your type can be rendered by an existing Render, you can easily create Render for your type from the existing one with contramap.

Render[A].contramap[B](A => B): Render[B]

Usage Example

import java.util.UUID
import extras.render.Render

final case class Id(value: UUID) extends AnyVal
object Id {
  implicit val idRender: Render[Id] = Render[UUID].contramap(_.value)
}

import extras.render.syntax._
Id(UUID.randomUUID()).render
// res5: String = "c442b977-f242-43bd-a84d-7200948c2ca1"

final case class Name(value: String) extends AnyVal
object Name {
  implicit val nameRender: Render[Name] = Render[String].contramap(_.value)
}

Name("Kevin").render
// res6: String = "Kevin"