Container.scala

package lascala.sgs.ch5.invariants

import cats.data.State
import cats.implicits._
import eu.timepit.refined._
import eu.timepit.refined.api.Refined
import eu.timepit.refined.auto._
import eu.timepit.refined.numeric._
import shapeless._ ; import syntax.singleton._ ; import record._

import Container._

case class Container[GI <: GroupIndex](
  group: Set[ContainerIndex[GI]],
  amount: Double Refined NonNegative,
)

object Container {
  type GroupIndex = Char
  type ContainerIndex[GI <: GroupIndex] = Char

  val world =  {
    ('a' ->> Container['a']('a')) ::
    ('b' ->> Container['b']('b')) ::
    ('c' ->> Container['c']('c')) ::
    ('d' ->> Container['d']('d')) ::
    HNil
  }

  def apply[GI <: GroupIndex](index: ContainerIndex[GI]): Container[GI] = {
    new Container[GI](Set(index), 0.0)
  }

}