graph.scala

// A port is just identified by an Int
type Port = Int

// A component has a name and input/ouput ports
final case class Comp[A, B](name: String, inputs: Ports[A], outputs: Ports[B])

// the state monad building the list of components Comp
type GraphM[A] = ((Port, List[Comp[_, _]])) => ((Port, List[Comp[_, _]]), A)

// the kleisli-like directed graph structure based on state monoad
final case class Graph[A, B](f: Ports[A] => GraphM[Ports[B]])

// For info, the different type of ports
sealed trait Ports[A]
case object UnitP extends Ports[Unit]
final case class BooleanP(port: Port) extends Ports[Boolean]
final case class IntP(port: Port) extends Ports[Int]
final case class DoubleP(port: Port) extends Ports[Double]
final case class PairP[A, B](l: Ports[A], r: Ports[B]) extends Ports[(A, B)]
final case class FunP[A, B](f: Graph[A, B]) extends Ports[A :=> B]