SecurePrinter typeclass

SecurePrinter.scala

import scala.annotation.implicitNotFound
import scala.language.{higherKinds, implicitConversions}

/**
 * A typeclass of securely printable values.
 *
 * Only primitive values and values that are marked as securely printable by default.
 *
 * You can extend new types as securely printable by adding an implicit printable to the
 * companion object of the class.
 *
 * {{{
 *   class NewType
 *   object NewType {
 *     implicit lazy val printable = SecurelyPrintable.usingToString[NewType]
 *   }
 * }}}
 */
@implicitNotFound("No implicit SecurePrinter found for type ${T}. " +
  "Implement or import an implicit SecurePrinter[${T}]."
)
trait SecurePrinter[-T] {

  def write(value: T): String
}

object SecurePrinter {

  def of[T: SecurePrinter]: SecurePrinter[T] = implicitly

  def using[T](asString: T => String): SecurePrinter[T] = new SecurePrinter[T] {
    override def write(value: T): String = asString(value)
  }

  def usingToString[T <: AnyRef]: SecurePrinter[T] = new SecurePrinter[T] {
    override def write(value: T): String = value.toString
  }

  implicit object SecurePrinterString extends SecurePrinter[String] {
    override def write(value: String): String = value
  }

  implicit object SecurePrinterAnyVal extends SecurePrinter[AnyVal] {
    override def write(value: AnyVal): String = value.toString
  }

  /**
   * Creates a printer that prints the class name with all the items separated by commas.
   *
   * This mimics the way case classes, tuples, and Scala collections are printed.
   */
  implicit def TraversableSecurePrinter[T](implicit printer: SecurePrinter[T]): SecurePrinter[Traversable[T]] = {
    new SecurePrinter[Traversable[T]] {
      override def write(ts: Traversable[T]): String = {
        val className = ts.getClass.getSimpleName
        val builder = new StringBuilder(className)
        builder.append('(')
        if (ts.nonEmpty) {
          val iter = ts.toIterator
          builder.append(printer.write(iter.next()))
          while (iter.hasNext) {
            builder.append(',')
            builder.append(' ')
            builder.append(printer.write(iter.next()))
          }
        }
        builder.append(')')
        builder.result()
      }
    }
  }
}

Turns out I don't need C at all. I fixed it.

Thanks!!