Share ComposeNode definition, provide Parallel instance between `…

…RecProg` and `RecApProg`.

core/src/main/scala-2/composefree/PackageCompat.scala

@@ -4,10 +4,6 @@ import cats.~>
 import cats.data.EitherK
 import cats.free.{Free, FreeApplicative}
 
-sealed trait ComposeNode[M[_], A]
-final case class MNode[M[_], A](run: Free[RecNode[M, *], A]) extends ComposeNode[M, A]
-final case class ANode[M[_], A](run: FreeApplicative[RecNode[M, *], A]) extends ComposeNode[M, A]
-
 trait PackageCompat {
   final type RecNode[M[_], A] = EitherK[ComposeNode[M, *], M, A]
   object RecNode {

core/src/main/scala-3/composefree/PackageCompat.scala

@@ -3,10 +3,6 @@ package composefree
 import cats.~>
 import cats.free.{Free, FreeApplicative}
 
-sealed trait ComposeNode[M[_], A]
-final case class MNode[M[_], A](run: RecProg[M, A]) extends ComposeNode[M, A]
-final case class ANode[M[_], A](run: FreeApplicative[RecNode[M, *], A]) extends ComposeNode[M, A]
-
 type RecNode[M[_], A] = ComposeNode[M, A] | M[A]
 object RecNode {
   inline def fold[M[_], F[_], A](n: RecNode[M, A])(c: ComposeNode[M, *] ~> F, m: M ~> F): F[A] =

core/src/main/scala/composefree/ComposeNode.scala

@@ -0,0 +1,22 @@
+package composefree
+
+import cats.{~>, Applicative, Monad, Parallel}
+
+sealed trait ComposeNode[M[_], A]
+final case class MNode[M[_], A](run: RecProg[M, A]) extends ComposeNode[M, A]
+final case class ANode[M[_], A](run: RecApProg[M, A]) extends ComposeNode[M, A]
+
+object ComposeNode {
+  implicit def recProgParallel[M[_]]: Parallel.Aux[RecProg[M, *], RecApProg[M, *]] =
+    new Parallel[RecProg[M, *]] {
+      type F[a] = RecApProg[M, a]
+      val applicative = Applicative[RecApProg[M, *]]
+      val monad = Monad[RecProg[M, *]]
+      val parallel = new (RecProg[M, *] ~> RecApProg[M, *]) {
+        def apply[A](p: RecProg[M, A]): RecApProg[M, A] = RecApProg.liftCN(MNode(p))
+      }
+      val sequential = new (RecApProg[M, *] ~> RecProg[M, *]) {
+        def apply[A](p: RecApProg[M, A]): RecProg[M, A] = RecProg.liftCN(ANode(p))
+      }
+    }
+}