higher-kinded heterogeneous lists: MList[M[_]]

natural transformations: ~>[A[_], B[_]]
Scala 2.8

util/collection/HList.scala

@@ -0,0 +1,22 @@
+package sbt
+
+import Types._
+
+sealed trait HList
+{
+	type Up <: MList[Id]
+	def up: Up
+}
+sealed trait HNil extends HList
+{
+	type Up = MNil[Id]
+	def up = MNil
+	def :+: [G](g: G): G :+: HNil = HCons(g, this)
+}
+object HNil extends HNil
+final case class HCons[H, T <: HList](head : H, tail : T) extends HList
+{
+	type Up = MCons[H, T#Up, Id]
+	def up = MCons[H,T#Up, Id](head, tail.up)
+	def :+: [G](g: G): G :+: H :+: T = HCons(g, this)
+}

util/collection/HLists.scala

@@ -1,29 +0,0 @@
-// stripped down version of http://trac.assembla.com/metascala/browser/src/metascala/HLists.scala
-//   Copyright (c) 2009, Jesper Nordenberg
-//   new BSD license, see licenses/LICENSE_MetaScala
-
-package xsbt
-
-object HLists extends HLists
-trait HLists
-{
-	object :: { def unapply[H,T<:HList](list: HCons[H,T]) = Some((list.head,list.tail)) }
-	type ::[H, T <: HList] = HCons[H, T]
-}
-
-object HNil extends HNil
-sealed trait HList {
-	 type Head
-	 type Tail <: HList
-}
-sealed class HNil extends HList {
-	type Head = Nothing
-	type Tail = HNil
-	def ::[T](v : T) = HCons(v, this)
-}
-
-final case class HCons[H, T <: HList](head : H, tail : T) extends HList {
-	type Head = H
-	type Tail = T
-	def ::[T](v : T) = HCons(v, this)
-}

util/collection/MList.scala

@@ -0,0 +1,42 @@
+package sbt
+
+import Types._
+
+sealed trait MList[M[_]]
+{
+	type Map[N[_]] <: MList[N]
+	def map[N[_]](f: M ~> N): Map[N]
+
+	type Down <: HList
+	def down: Down
+
+	def toList: List[M[_]]
+}
+final case class MCons[H, T <: MList[M], M[_]](head: M[H], tail: T) extends MList[M]
+{
+	type Down = M[H] :+: T#Down
+	def down = HCons(head, tail.down)
+
+	type Map[N[_]] = MCons[H, T#Map[N], N]
+	def map[N[_]](f: M ~> N) = MCons( f(head), tail.map(f) )
+
+	def :^: [G](g: M[G]): MCons[G, MCons[H, T, M], M] = MCons(g, this)
+
+	def toList = head :: tail.toList
+}
+sealed class MNil[M[_]] extends MList[M]
+{
+	type Down = HNil
+	def down = HNil
+	
+	type Map[N[_]] = MNil[N]
+	def map[N[_]](f: M ~> N): MNil[N] = new MNil[N]
+
+	def :^: [H](h: M[H]): MCons[H, MNil[M], M] = MCons(h, this)
+
+	def toList = Nil
+}
+object MNil extends MNil[Id]
+{
+	implicit def apply[N[_]]: MNil[N] = new MNil[N]
+}

util/collection/NOTICE

@@ -1,7 +1,3 @@
 Simple Build Tool: Collection Component
-Copyright 2009  Mark Harrah
-Licensed under BSD-style license (see LICENSE)
-
-Portions based on MetaScala
-Copyright (c) 2009, Jesper Nordenberg
-Licensed under BSD-style license (see licenses/LICENSE_MetaScala)
+Copyright 2010  Mark Harrah
+Licensed under BSD-style license (see LICENSE)

util/collection/TreeHashSet.scala

@@ -1,25 +0,0 @@
-/* sbt -- Simple Build Tool
- * Copyright 2009  Mark Harrah
- */
-package xsbt
-
-import scala.collection.{mutable,immutable}
-
- // immutable.HashSet is not suitable for multi-threaded access, so this
-// implementation uses an underlying immutable.TreeHashMap, which is suitable
-object TreeHashSet
-{
-	def apply[T](contents: T*) = new TreeHashSet(immutable.TreeHashMap( andUnit(contents) : _*))
-	def andUnit[T](contents: Iterable[T]) = contents.map(c => (c,()) ).toSeq
-}
-final class TreeHashSet[T](backing: immutable.TreeHashMap[T,Unit]) extends immutable.Set[T]
-{
-	import TreeHashSet.andUnit
-	override def contains(t: T) = backing.contains(t)
-	override def ++(s: Iterable[T]) = new TreeHashSet(backing ++ andUnit(s))
-	override def +(s: T) = ++( Seq(s) )
-	override def -(s: T) = new TreeHashSet(backing - s)
-	override def elements = backing.keys
-	override def empty[A] = TreeHashSet[A]()
-	override def size = backing.size
-}

util/collection/TypeFunctions.scala

@@ -0,0 +1,16 @@
+package sbt
+
+trait TypeFunctions
+{
+	type Id[X] = X
+	trait Const[A] { type Apply[B] = A }
+	trait Down[M[_]] { type Apply[B] = Id[M[B]] }
+
+	trait ~>[A[_], B[_]]
+	{
+		def apply[T](a: A[T]): B[T]
+	}
+	def Id: Id ~> Id =
+		new ~>[Id, Id] { def apply[T](a: T): T = a }
+}
+object TypeFunctions extends TypeFunctions

util/collection/Types.scala

@@ -0,0 +1,8 @@
+package sbt
+
+object Types extends TypeFunctions
+{
+	val :^: = MCons
+	val :+: = HCons
+	type :+:[H, T <: HList] = HCons[H,T]
+}