Define non empty list with max size. newtype with smart constructor. Try to set the max size value at compile time

NonEmptyListMaxSize.scala

package domain.common.collection

import domain.common.number.strictpositiveint.StrictPositiveInt
import scalaz.Scalaz.ToEitherOps
import scalaz.{@@, NonEmptyList, Tag, \/}

object NonEmptyListMaxSize {
	private[NonEmptyListMaxSize] sealed trait NonEmptyListMaxSize2Tag
	type NonEmptyListMaxSize2[A] = NonEmptyList[A] @@ NonEmptyListMaxSize2Tag

	sealed trait NonEmptyListMaxSizeError
	case class NonEmptyListMaxSizeExceeded(maxSize: StrictPositiveInt, size: Int) extends NonEmptyListMaxSizeError

	object NonEmptyListMaxSize2 {
		def apply[A](rawValue: NonEmptyList[A]): NonEmptyListMaxSizeError \/ NonEmptyListMaxSize2[A] = {
			if(rawValue.size <= 2) buildType(rawValue).right
			else NonEmptyListMaxSizeExceeded(StrictPositiveInt.TWO, rawValue.size).left
		}

		/**
		  * a.k.a unwrap function
		  * @param nel
		  * @return the unwrapped NonEmptyList value
		  */
		def rawValue[A](nel: NonEmptyListMaxSize2[A]): NonEmptyList[A] = Tag.unwrap(nel)

		/**
		  * Allow to use scalaz Show typeclass
		  */
		//implicit val showNonEmptyListMaxSize2[A]: Show[NonEmptyListMaxSize2[A]] = Show shows { i => s"NonEmptyListMaxSize2(${Tag.unwrap(i)})"}

		private def buildType[A](nel: NonEmptyList[A]) = Tag.apply[NonEmptyList[A], NonEmptyListMaxSize2Tag](nel)

		implicit class NonEmptyListMaxSize2Ops[A](nel_2: NonEmptyListMaxSize2[A]) {
			def list: List[A] = rawValue(nel_2).list
			def head: A = rawValue(nel_2).head
			def tail: List[A] = rawValue(nel_2).tail
			def +(x: A): NonEmptyListMaxSizeError \/ NonEmptyListMaxSize2[A] = apply(rawValue(nel_2).:::>(x :: Nil))
		}
	}
}

En fait je voudrais pouvoir "variabiliser" rawValue.size <= 2 dans la méthode apply mais au compile time.

Pour pouvoir définir le MaxSize dans la signature du type et définir par exemple :

case class Toto(maliste: NonEmptyListmaxSize[MaxSize_5, String])