No implicit argument of type Nothing?

Question
4

Here’s what I did for better code organization.

├── Main.scala
└── myutils
    ├── BaseEncoder.scala
    ├── CaseClass2CSV.scala
    ├── FieldEncoder.scala
    ├── RowEncoder.scala
    └── TupleEncoder.scala

Each file is as follows.

BaseEncoder.scala

package myutils
package encoder
package instances

given FieldEncoder[Int] with
  def encodeField(x: Int) = x.toString

given FieldEncoder[Boolean] with
  def encodeField(x: Boolean) = if x then "true" else "false"

given FieldEncoder[String] with
  def encodeField(x: String) = x

CaseClass2CSV.scala

package myutils
package encoder
package instances
package func
 
def tupleToCsv[X <: Tuple: RowEncoder](tuple: X): List[String] =
  summon[RowEncoder[X]].encodeRow(tuple)

FieldEncoder.scala

package myutils
package encoder 

trait FieldEncoder[A]:
  def encodeField(a: A): String

RowEncoder.scala

package myutils
package encoder 

type Row = List[String]

trait RowEncoder[A]:
  def encodeRow(a: A): Row

TupleEncoder.scala

package myutils
package encoder 
package instances

given RowEncoder[EmptyTuple] with
  def encodeRow(empty: EmptyTuple) =
    List.empty

given [H: FieldEncoder, T <: Tuple: RowEncoder]: RowEncoder[H *: T] with
  def encodeRow(tuple: H *: T) =
    summon[FieldEncoder[H]].encodeField(tuple.head) :: summon[RowEncoder[T]]
      .encodeRow(tuple.tail)

I ran the following main and it works nicely :slight_smile:

import myutils.encoder.instances.func.tupleToCsv
import myutils.encoder.instances.given

@main def hello: Unit = {
  println(tupleToCsv((42, true, "Hello")))
}

Any suggestion to make it better is welcome! I’m very new to scala and it would be lovely to have some advice from experienced scala users.