Implicit encoder for a trait type parameter

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0

I would like to encode to json a field of type List[E] using argonaut lib.

sealed trait Msg[E] {
  val contents: List[E]    

  def send(): Unit = {
    val json = contents.asJson
    println("Sending json: " + json.toString())
  }
}

Then i have a StringMsg case class:

case class StringMsg(contents: List[String]) extends Msg[String]

The argonaut lib defines a JsonIdentity[J] trait:

trait JsonIdentity[J] {
  val j: J

  /**
   * Encode to a JSON value using the given implicit encoder.
   */
  def jencode(implicit e: EncodeJson[J]): Json =
    e(j)
}

When i create a new instance of StringMsg and call the send() method, i have the following error:

StringMsg(List("a","b")).send()

could not find implicit value for parameter e: argonaut.EncodeJson[List[E]]

asked 12 secs ago

Nix

192

Implicit encoder for a trait type parameter