morphling.Constructors.scala Maven / Gradle / Ivy

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package morphling

import cats.data.NonEmptyList
import cats.syntax.list.*
import shapeless.ops.coproduct.ToHList
import shapeless.ops.hlist.{Align, Comapped, ToTraversable}
import shapeless.{Prism as _, *}

import scala.annotation.implicitNotFound

/**
 * Implicit proof type
 */
@implicitNotFound(msg = "Cannot prove the completeness of your oneOf definition; you may have not provided an alternative for each constructor of your sum type ${I}")
sealed trait Constructors[I, F[_], H <: HList] {
  def toNel(h: H): NonEmptyList[F[?]]
}

object Constructors {
  implicit def evidence[I, F[_], C <: Coproduct, H0 <: HList, H1 <: HList, H <: HList](implicit
      G: Generic.Aux[I, C],
      L: ToHList.Aux[C, H1],
      M: Comapped.Aux[H, F, H0],
      A: Align[H0, H1],
      T: ToTraversable.Aux[H, List, F[?]]
  ): Constructors[I, F, H] = new Constructors[I, F, H] {
    def toNel(h: H): NonEmptyList[F[?]] =
      h.toList.toNel.get
  }
}