runFree

gistfile1.scala

  def runFree[S[+_], M[_]](f: S ~> M)(implicit M: Monad[M]): ({type λ[α] = Free[S, α]})#λ ~> M =
    new (({type λ[α] = Free[S, α]})#λ ~> M) {
      def apply[A](fr: Free[S, A]) = fr.foldMap[M, A](f)
    }

  def runFreeC[S[+_], M[_]](f: S ~> M)(implicit M: Monad[M]): ({type λ[α] = FreeC[S, α]})#λ ~> M =
    new (({type λ[α] = FreeC[S, α]})#λ ~> M) {
      def apply[A](fr: FreeC[S, A]) = fr.runM[M, A](coyo => M.map(f(coyo.fi))(coyo.k))
    }