Many small changes and cleanup.

CHANGELOG/breaking.md

@@ -0,0 +1,2 @@
+- renamed `FunctorT#map` and `TraverseT#traverse` to `mapT` and `traverseT`
+- added a bunch of new operations (many pulled from Quasar)

build.sbt

@@ -32,6 +32,7 @@ lazy val standardSettings = Seq[Setting[_]](
   headers := Map(
     "scala" -> Apache2_0("2014–2016", "SlamData Inc."),
     "java"  -> Apache2_0("2014–2016", "SlamData Inc.")),
+  scalaOrganization := "org.typelevel",
   scalaVersion := "2.11.8",
   logBuffered in Compile := false,
   logBuffered in Test := false,
@@ -47,9 +48,8 @@ lazy val standardSettings = Seq[Setting[_]](
     "JBoss repository" at "https://repository.jboss.org/nexus/content/repositories/",
     "Scalaz Bintray Repo" at "http://dl.bintray.com/scalaz/releases",
     "bintray/non" at "http://dl.bintray.com/non/maven"),
-  addCompilerPlugin("org.spire-math" %% "kind-projector"   % "0.9.2"),
+  addCompilerPlugin("org.spire-math" %% "kind-projector"   % "0.9.3"),
   addCompilerPlugin("org.scalamacros" % "paradise"         % "2.1.0" cross CrossVersion.full),
-  addCompilerPlugin("com.milessabin"  % "si2712fix-plugin" % "1.2.0" cross CrossVersion.full),
   ScoverageKeys.coverageHighlighting := true,
 
   scalacOptions ++= Seq(
@@ -67,9 +67,11 @@ lazy val standardSettings = Seq[Setting[_]](
     "-Yno-imports",
     "-Ywarn-dead-code", // N.B. doesn't work well with the ??? hole
     "-Ywarn-numeric-widen",
+    "-Ypartial-unification",
     "-Ywarn-unused-import",
     "-Ywarn-value-discard"),
-  scalacOptions in (Compile,doc) ++= Seq("-groups", "-implicits"),
+  scalacOptions in (Compile, doc) ++= Seq("-groups", "-implicits"),
+  scalacOptions in (Compile, doc) -= "-Xfatal-warnings",
   scalacOptions in (Test, console) --= Seq(
     "-Yno-imports",
     "-Ywarn-unused-import"),
@@ -85,7 +87,7 @@ lazy val standardSettings = Seq[Setting[_]](
   licenses += ("Apache 2", url("http://www.apache.org/licenses/LICENSE-2.0")),
 
   checkHeaders := {
-    if ((createHeaders in Compile).value.nonEmpty) error("headers not all present")
+    if ((createHeaders in Compile).value.nonEmpty) sys.error("headers not all present")
   })
 
 // Using a Seq of desired warts instead of Warts.allBut due to an incremental compilation issue.

core/shared/src/main/scala/matryoshka/Corecursive.scala

@@ -40,33 +40,33 @@ trait Corecursive[T] extends Based[T] {
       : M[T] =
     f(a).flatMap(_.traverse(anaM(_)(f))) ∘ (embed(_))
 
-  def gana[N[_], A]
+  def gana[N[_]: Monad, A]
     (a: A)
     (k: DistributiveLaw[N, Base], f: GCoalgebra[N, Base, A])
-    (implicit BF: Functor[Base], N: Monad[N])
+    (implicit BF: Functor[Base])
       : T = {
-    def loop(x: N[Base[N[A]]]): T = embed(k(x) ∘ (x => loop(N.lift(f)(x.join))))
+    def loop(x: N[Base[N[A]]]): T = embed(k(x) ∘ (x => loop(x.join ∘ f)))
 
     loop(f(a).point[N])
   }
 
-  def ganaM[N[_]: Traverse, M[_]: Monad, A](
+  def ganaM[N[_]: Monad: Traverse, M[_]: Monad, A](
     a: A)(
     k: DistributiveLaw[N, Base], f: GCoalgebraM[N, M, Base, A])(
-    implicit BT: Traverse[Base], N: Monad[N]):
+    implicit BT: Traverse[Base]):
       M[T] = {
     def loop(x: N[Base[N[A]]]): M[T] =
-      k(x).traverse(x => N.lift(f)(x.join).sequence >>= loop) ∘ (embed(_))
+      k(x).traverse(_.join.traverse(f) >>= loop) ∘ (embed(_))
 
     f(a) ∘ (_.point[N]) >>= loop
   }
 
-  def elgotAna[N[_], A](
+  def elgotAna[N[_]: Monad, A](
     a: A)(
     k: DistributiveLaw[N, Base], ψ: ElgotCoalgebra[N, Base, A])(
-    implicit BF: Functor[Base], N: Monad[N]):
+    implicit BF: Functor[Base]):
       T = {
-    def loop(x: N[Base[A]]): T = embed(k(x) ∘ (x => loop(N.lift(ψ)(x).join)))
+    def loop(x: N[Base[A]]): T = embed(k(x) ∘ (x => loop(x >>= ψ)))
 
     loop(ψ(a))
   }
@@ -117,7 +117,7 @@ trait Corecursive[T] extends Based[T] {
     implicit T: Recursive.Aux[T, Base], BF: Functor[Base], N: Monad[N]):
       T = {
     def loop(ma: N[A]): T =
-      embed(k(N.lift(ψ)(ma)) ∘ (x => ana(loop(x.join))(x => e(T.project(x)))))
+      embed(k(ma ∘ ψ) ∘ (x => ana(loop(x.join))(x => e(T.project(x)))))
 
     loop(a.point[N])
   }

core/shared/src/main/scala/matryoshka/FunctorT.scala

@@ -47,49 +47,70 @@ import simulacrum._
   * - `transCata` – akin to Fixplate’s `restructure`
   */
 @typeclass trait FunctorT[T[_[_]]] {
-  @op("∘") def map[F[_]: Functor, G[_]: Functor](t: T[F])(f: F[T[F]] => G[T[G]]):
+  def mapT[F[_]: Functor, G[_]: Functor](t: T[F])(f: F[T[F]] => G[T[G]]):
       T[G]
 
   def transCataT[F[_]: Functor](t: T[F])(f: T[F] => T[F]): T[F] =
-    f(map(t)(_.map(transCataT(_)(f))))
+    f(mapT(t)(_.map(transCataT(_)(f))))
+
+  /** This behaves like [[matryoshka.Recursive.elgotPara]]`, but it’s harder to
+    * see from the types that in the tuple, `_2` is the result so far and `_1`
+    * is the original structure.
+    */
+  def transParaT[F[_]: Functor](t: T[F])(f: ((T[F], T[F])) => T[F]): T[F] =
+    f((t, mapT(t)(_.map(transParaT(_)(f)))))
 
   def transAnaT[F[_]: Functor](t: T[F])(f: T[F] => T[F]): T[F] =
-    map(f(t))(_.map(transAnaT(_)(f)))
+    mapT(f(t))(_.map(transAnaT(_)(f)))
 
+  /** This behaves like [[matryoshka.Corecursive.elgotApo]]`, but it’s harder to
+    * see from the types that in the disjunction, `-\/` is the final result for
+    * this node, while `\/-` means to keep processing the children.
+    */
   def transApoT[F[_]: Functor](t: T[F])(f: T[F] => T[F] \/ T[F]): T[F] =
-    f(t).fold(Predef.identity, map(_)(_.map(transApoT(_)(f))))
+    f(t).fold(Predef.identity, mapT(_)(_.map(transApoT(_)(f))))
+
+  def transHyloT[F[_]: Functor](t: T[F])(φ: T[F] => T[F], ψ: T[F] => T[F]):
+      T[F] =
+    φ(mapT(ψ(t))(_ ∘ (transHyloT(_)(φ, ψ))))
 
   def transCata[F[_]: Functor, G[_]: Functor](t: T[F])(f: AlgebraicTransform[T, F, G]): T[G] =
-    map(t)(ft => f(ft.map(transCata(_)(f))))
+    mapT(t)(ft => f(ft.map(transCata(_)(f))))
 
   def transAna[F[_]: Functor, G[_]: Functor](t: T[F])(f: CoalgebraicTransform[T, F, G]): T[G] =
-    map(t)(f(_).map(transAna(_)(f)))
+    mapT(t)(f(_).map(transAna(_)(f)))
 
   def transPrepro[F[_]: Functor, G[_]: Functor](t: T[F])(e: F ~> F, f: AlgebraicTransform[T, F, G]): T[G] =
-    map(t)(ft => f(ft ∘ (x => transPrepro(transCata[F, F](x)(e(_)))(e, f))))
+    mapT(t)(ft => f(ft ∘ (x => transPrepro(transCata[F, F](x)(e(_)))(e, f))))
 
   def transPostpro[F[_]: Functor, G[_]: Functor](t: T[F])(e: G ~> G, f: CoalgebraicTransform[T, F, G]): T[G] =
-    map(t)(f(_) ∘ (x => transAna(transPostpro(x)(e, f))(e)))
+    mapT(t)(f(_) ∘ (x => transAna(transPostpro(x)(e, f))(e)))
 
   def transPara[F[_]: Functor, G[_]: Functor](t: T[F])(f: GAlgebraicTransform[T, (T[F], ?), F, G]):
       T[G] =
-    map(t)(ft => f(ft.map(tf => (tf, transPara(tf)(f)))))
+    mapT(t)(ft => f(ft.map(tf => (tf, transPara(tf)(f)))))
 
   def transApo[F[_]: Functor, G[_]: Functor](t: T[F])(f: GCoalgebraicTransform[T, (T[G] \/ ?), F, G]):
       T[G] =
-    map(t)(f(_).map(_.fold(Predef.identity, transApo(_)(f))))
+    mapT(t)(f(_).map(_.fold(Predef.identity, transApo(_)(f))))
+
+  def transHylo[F[_]: Functor, G[_]: Functor, H[_]: Functor](
+    t: T[F])(
+    φ: G[T[H]] => H[T[H]], ψ: F[T[F]] => G[T[F]]):
+      T[H] =
+    mapT(t)(ft => φ(ψ(ft) ∘ (transHylo(_)(φ, ψ))))
 
   def topDownCata[F[_]: Functor, A](t: T[F], a: A)(f: (A, T[F]) => (A, T[F])):
       T[F] = {
     val (a0, tf) = f(a, t)
-    map(tf)(_.map(topDownCata(_, a0)(f)))
+    mapT(tf)(_.map(topDownCata(_, a0)(f)))
   }
 }
 
 object FunctorT {
-  implicit def birecursiveTFunctorT[T[_[_]]: RecursiveT: CorecursiveT]: FunctorT[T] =
+  implicit def birecursiveT[T[_[_]]: RecursiveT: CorecursiveT]: FunctorT[T] =
     new FunctorT[T] {
-      def map[F[_], G[_]](t: T[F])(f: F[T[F]] => G[T[G]])(implicit F: Functor[F], G: Functor[G]) =
+      def mapT[F[_], G[_]](t: T[F])(f: F[T[F]] => G[T[G]])(implicit F: Functor[F], G: Functor[G]) =
         CorecursiveT[T].embedT(f(RecursiveT[T].projectT(t)))
     }
 }

core/shared/src/main/scala/matryoshka/Recursive.scala

@@ -304,8 +304,6 @@ trait Recursive[T] extends Based[T] {
 }
 
 object Recursive {
-  type Aux[T, F[_]] = Recursive[T] { type Base[A] = F[A] }
-
   def equal[T, F[_]: Functor]
     (implicit T: Recursive.Aux[T, F], F: Delay[Equal, F])
       : Equal[T] =
@@ -318,6 +316,8 @@ object Recursive {
   // NB: The rest of this is what would be generated by simulacrum, except this
   //     type class is too complicated to take advantage of that.
 
+  type Aux[T, F[_]] = Recursive[T] { type Base[A] = F[A] }
+
   def apply[T, F[_]](implicit instance: Aux[T, F]): Aux[T, F] = instance
 
   trait Ops[T, F[_]] {

core/shared/src/main/scala/matryoshka/TraverseT.scala

@@ -20,37 +20,49 @@ import scalaz._, Scalaz._
 import simulacrum._
 
 @typeclass trait TraverseT[T[_[_]]] extends FunctorT[T] {
-  def traverse[M[_]: Applicative, F[_]: Functor, G[_]: Functor](t: T[F])(f: F[T[F]] => M[G[T[G]]]):
-      M[T[G]]
+  def traverseT[M[_]: Applicative, F[_]: Functor, G[_]: Functor]
+    (t: T[F])
+    (f: F[T[F]] => M[G[T[G]]])
+      : M[T[G]]
 
-  def map[F[_]: Functor, G[_]: Functor](t: T[F])(f: F[T[F]] => G[T[G]]) = traverse[Id, F, G](t)(f)
+  override def mapT[F[_]: Functor, G[_]: Functor]
+    (t: T[F])
+    (f: F[T[F]] => G[T[G]]) =
+    traverseT[Id, F, G](t)(f)
 
-  def transCataTM[F[_]: Traverse, M[_]: Monad](t: T[F])(f: T[F] => M[T[F]]): M[T[F]] =
-    traverse(t)(_.traverse(transCataTM(_)(f))).flatMap(f)
+  def transCataTM[F[_]: Traverse, M[_]: Monad](t: T[F])(f: T[F] => M[T[F]])
+      : M[T[F]] =
+    traverseT(t)(_.traverse(transCataTM(_)(f))).flatMap(f)
 
-  def transAnaTM[F[_]: Traverse, M[_]: Monad](t: T[F])(f: T[F] => M[T[F]]):
-      M[T[F]] =
-    f(t).flatMap(traverse(_)(_.traverse(transAnaTM(_)(f))))
+  def transAnaTM[F[_]: Traverse, M[_]: Monad](t: T[F])(f: T[F] => M[T[F]])
+      : M[T[F]] =
+    f(t).flatMap(traverseT(_)(_.traverse(transAnaTM(_)(f))))
 
-  def transCataM[M[_]: Monad, F[_]: Traverse, G[_]: Functor](t: T[F])(f: AlgebraicTransformM[T, M, F, G]): M[T[G]] =
-    traverse(t)(_.traverse(transCataM(_)(f)).flatMap(f))
+  def transCataM[M[_]: Monad, F[_]: Traverse, G[_]: Functor]
+    (t: T[F])
+    (f: AlgebraicTransformM[T, M, F, G])
+      : M[T[G]] =
+    traverseT(t)(_.traverse(transCataM(_)(f)).flatMap(f))
 
-  def transAnaM[M[_]: Monad, F[_]: Functor, G[_]: Traverse](t: T[F])(f: CoalgebraicTransformM[T, M, F, G]): M[T[G]] =
-    traverse(t)(f(_).flatMap(_.traverse(transAnaM(_)(f))))
+  def transAnaM[M[_]: Monad, F[_]: Functor, G[_]: Traverse]
+    (t: T[F])
+    (f: CoalgebraicTransformM[T, M, F, G])
+      : M[T[G]] =
+    traverseT(t)(f(_).flatMap(_.traverse(transAnaM(_)(f))))
 
   def topDownCataM[F[_]: Traverse, M[_]: Monad, A](
     t: T[F], a: A)(
     f: (A, T[F]) => M[(A, T[F])]):
       M[T[F]] =
     f(a, t).flatMap { case (a, tf) =>
-      traverse(tf)(_.traverse(topDownCataM(_, a)(f)))
+      traverseT(tf)(_.traverse(topDownCataM(_, a)(f)))
     }
 }
 
 object TraverseT {
-  implicit def birecursiveTTraverseT[T[_[_]]: RecursiveT: CorecursiveT]: TraverseT[T] =
+  implicit def birecursiveT[T[_[_]]: RecursiveT: CorecursiveT]: TraverseT[T] =
     new TraverseT[T] {
-      def traverse[M[_]: Applicative, F[_]: Functor, G[_]: Functor]
+      def traverseT[M[_]: Applicative, F[_]: Functor, G[_]: Functor]
         (t: T[F])
         (f: F[T[F]] => M[G[T[G]]]) =
         f(RecursiveT[T].projectT(t)).map(CorecursiveT[T].embedT[G])

core/shared/src/main/scala/matryoshka/data/Mu.scala

@@ -23,7 +23,7 @@ import scalaz._, Scalaz._
 /** This is for inductive (finite) recursive structures, models the concept of
   * “data”, aka, the “least fixed point”.
   */
-final case class Mu[F[_]](unMu: λ[A => Algebra[F, A]] ~> Id)
+final case class Mu[F[_]](unMu: Algebra[F, ?] ~> Id)
 object Mu {
   implicit def recursiveT: RecursiveT[Mu] = new RecursiveT[Mu] {
     // FIXME: ugh, shouldn’t have to redefine `lambek` in here?
@@ -34,8 +34,8 @@ object Mu {
 
   implicit def corecursiveT: CorecursiveT[Mu] = new CorecursiveT[Mu] {
     def embedT[F[_]: Functor](t: F[Mu[F]]) =
-      Mu(new (λ[A => (F[A] => A)] ~> Id) {
-        def apply[A](fa: F[A] => A): A = fa(t.map(recursiveT.cataT(_)(fa)))
+      Mu(new (Algebra[F, ?] ~> Id) {
+        def apply[A](fa: Algebra[F, A]): A = fa(t.map(recursiveT.cataT(_)(fa)))
       })
   }
 

core/shared/src/main/scala/matryoshka/data/cofree.scala

@@ -20,7 +20,6 @@ import matryoshka._
 import matryoshka.patterns.EnvT
 
 import scalaz._
-import scalaz.syntax.functor._
 
 trait CofreeInstances {
   implicit def cofreeRecursive[F[_], A]: Recursive.Aux[Cofree[F, A], EnvT[A, F, ?]] =
@@ -39,12 +38,6 @@ trait CofreeInstances {
         Cofree(t.ask, t.lower)
     }
 
-  implicit def cofreeTraverseT[A]: TraverseT[Cofree[?[_], A]] =
-    new TraverseT[Cofree[?[_], A]] {
-      def traverse[M[_]: Applicative, F[_]: Functor, G[_]: Functor](t: Cofree[F, A])(f: F[Cofree[F, A]] => M[G[Cofree[G, A]]]) =
-        f(t.tail).map(Cofree(t.head, _))
-    }
-
   implicit def cofreeEqual[F[_]](implicit F: Delay[Equal, F]):
       Delay[Equal, Cofree[F, ?]] =
     new Delay[Equal, Cofree[F, ?]] {

core/shared/src/main/scala/matryoshka/data/free.scala

@@ -39,14 +39,6 @@ trait FreeInstances {
         t.run.fold(_.point[Free[F, ?]], Free.liftF(_).join)
     }
 
-  implicit def freeTraverseT[A]: TraverseT[Free[?[_], A]] =
-    new TraverseT[Free[?[_], A]] {
-      def traverse[M[_]: Applicative, F[_]: Functor, G[_]: Functor](t: Free[F, A])(f: F[Free[F, A]] => M[G[Free[G, A]]]) =
-        t.fold(
-          _.point[Free[G, ?]].point[M],
-          f(_).map(Free.liftF(_).join))
-    }
-
   implicit def freeEqual[F[_]: Functor](implicit F: Delay[Equal, F]):
       Delay[Equal, Free[F, ?]] =
     new Delay[Equal, Free[F, ?]] {

core/shared/src/main/scala/matryoshka/data/package.scala

@@ -20,6 +20,13 @@ import matryoshka.implicits._
 
 import scalaz._, Scalaz._
 
+/** This packages contains fixed-point operators as well as instances of
+  * recursion schemes for various extant data types.
+  *
+  * The reason these are relegated to their own package is because, in general,
+  * you should eschew using them directly, but rather rely on the type class
+  * constraints, and only require specific types at the boundaries.
+  */
 package object data
     extends CofreeInstances
     with EitherInstances
@@ -28,11 +35,6 @@ package object data
     with IListInstances
     with MaybeInstances {
 
-  // final class CofParaMPartiallyApplied[M[_]] { self =>
-  //   def apply[T[_[_]]: Corecursive, S[_]: Traverse, A, B](t: Cofree[S, A])(f: (A, S[(T[S], B)]) => M[B])(implicit M: Monad[M]): M[B] =
-  //     t.tail.traverse(cs => self(cs)(f) ∘ ((Recursive[Cofree[?[_], A]].convertTo[S, T](cs), _))) >>= (f(t.head, _))
-  // }
-
   /** NB: Since Cofree carries the functor, the resulting algebra is a cata, not
     *     a para.
     *

core/shared/src/main/scala/matryoshka/implicits/IdOps.scala

@@ -115,6 +115,18 @@ sealed class IdOps[A](self: A) {
     }
   }
 
+  object ganaM {
+    def apply[T] = new Aux[T]
+
+    final class Aux[T] {
+      def apply[N[_]: Monad: Traverse, M[_]: Monad, F[_]: Traverse]
+        (k: DistributiveLaw[N, F], f: GCoalgebraM[N, M, F, A])
+        (implicit T: Corecursive.Aux[T, F])
+          : M[T] =
+        T.ganaM(self)(k, f)
+    }
+  }
+
   object elgotAna {
     def apply[T] = new Aux[T]