diff --git a/src/strawman/collections/CollectionStrawMan2.scala b/src/strawman/collections/CollectionStrawMan2.scala
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+++ b/src/strawman/collections/CollectionStrawMan2.scala
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+package strawman.collections
+
+import Predef.{augmentString => _, wrapString => _, _}
+import scala.language.implicitConversions
+import scala.reflect.ClassTag
+
+/** A strawman architecture for new collections. It contains some
+ *  example collection classes and methods with the intent to expose
+ *  some key issues. It would be good to compare this to other
+ *  implementations of the same functionality, to get an idea of the
+ *  strengths and weaknesses of different collection architectures.
+ *
+ *  For a test file, see tests/run/CollectionTests.scala.
+ */
+object CollectionStrawMan1 {
+
+  type LengthTypeUnderlying = Long
+
+  final case class LengthType(u: LengthTypeUnderlying) extends AnyVal {
+    def +(other: LengthType) = LengthType(u + other.u)
+    def -(other: LengthType) = LengthType(u - other.u)
+    def /(other: LengthType) = LengthType(u / other.u)
+    def *(other: LengthType) = LengthType(u * other.u)
+    def <(other: LengthType) = u < other.u
+    def >(other: LengthType) = u > other.u
+    def <=(other: LengthType) = u <= other.u
+    def >=(other: LengthType) = u >= other.u
+  }
+
+  implicit def intToLengthType(x: Int): LengthType = LengthType(x)
+  implicit def lengthTypeToLong(x: LengthType): Long = x.u.toLong
+
+  /* ------------ Base Traits -------------------------------- */
+
+  /** Replaces TraversableOnce */
+  trait CanIterate[+A] {
+    def iterator: Iterator[A]
+  }
+
+  /** Base trait for instances that can construct a collection from an iterator */
+  trait FromIterator[+C[X] <: Iterable[X]] {
+    def fromIterator[B](it: Iterator[B]): C[B]
+  }
+
+  /** Base trait for companion objects of collections */
+  trait IterableFactory[+C[X] <: Iterable[X]] extends FromIterator[C] {
+    def empty[X]: C[X] = fromIterator(Iterator.empty)
+    def apply[A](xs: A*): C[A] = fromIterator(Iterator(xs: _*))
+  }
+
+  /** Base trait for generic collections */
+  trait Iterable[+A] extends CanIterate[A] with FromIterator[Iterable]
+
+  /** Base trait for sequence collections */
+  trait Seq[+A] extends Iterable[A] with FromIterator[Seq] {
+    def apply(i: LengthType): A
+    def length: LengthType
+  }
+
+  type View[A] = () => Iterator[A]
+
+  /* ------------ Operations ----------------------------------- */
+
+  /** Operations returning types unrelated to current collection */
+  trait Ops[A] extends Any {
+    def iterator: Iterator[A]
+    def foreach(f: A => Unit): Unit = iterator.foreach(f)
+    def foldLeft[B](z: B)(op: (B, A) => B): B = iterator.foldLeft(z)(op)
+    def foldRight[B](z: B)(op: (A, B) => B): B = iterator.foldRight(z)(op)
+    def indexWhere(p: A => Boolean): LengthType = iterator.indexWhere(p)
+    def isEmpty: Boolean = !iterator.hasNext
+    def head: A = iterator.next
+    def collectAs[C[X] <: Iterable[X]](fi: FromIterator[C]): C[A] = fi.fromIterator(iterator)
+  }
+
+  trait Viewable[A] extends Any {
+    def view: View[A]
+  }
+
+  /** Transforms returning same collection type */
+  trait MonoTransforms[A, Repr] extends Any {
+    protected def iter: Iterator[A]
+    protected def fromIter(it: => Iterator[A]): Repr
+    def partition(p: A => Boolean): (Repr, Repr) = {
+      val lookaheadTrue, lookaheadFalse = new ArrayBuffer[A]
+      val xs = Iterator.Partition[A](this, p, lookaheadTrue, lookaheadFalse)
+      val ys = Iterator.Partition[A](this, !p(_), lookaheadFalse, lookaheadTrue)
+      (fromIter(xs), fromIter(ys))
+    }
+    def drop(n: LengthType): Repr = fromIter(Iterator.Drop(iter, n))
+  }
+
+  /** Transforms returning same collection type constructor */
+  trait PolyTransforms[A, C[X]] extends Any {
+    protected def iter: Iterator[A]
+    protected def fromIter[B](it: => Iterator[B]): C[B]
+    def map[B](f: A => B): C[B] = fromIter(Iterator.Map(iter, f))
+    def flatMap[B](f: A => CanIterate[B]): C[B] = fromIter(Iterator.FlatMap(iter, f))
+    def ++[B >: A](xs: CanIterate[B]): C[B] = fromIter(Iterator.Concat(iter, xs))
+    def zip[B](xs: CanIterate[B]): C[(A, B)] = fromIter(Iterator.Zip(iter, xs.iterator))
+  }
+
+  /** Transforms that only apply to Seq */
+  trait MonoTransformsOfSeqs[A, Repr] extends Any with MonoTransforms[A, Repr] {
+    def reverse: Repr = fromIter(iter.reverse)
+  }
+
+  /** Implementation of Ops for all generic collections */
+  implicit class IterableOps[A](val c: Iterable[A])
+  extends AnyVal with Ops[A] {
+    def iterator = c.iterator
+  }
+
+  implicit class IterableIsViewable[A](val c: Iterable[A]) extends Viewable[A]{
+    def iterator: Iterator[A] = c.iterator
+    def view: View[A] = iterator _
+  }
+
+  /** Implementation of MonoTransforms for all generic collections */
+  implicit class IterableMonoTransforms[A, C[X] <: Iterable[X]](val c: Iterable[A] with FromIterator[C])
+  extends AnyVal with MonoTransforms[A, C[A]] {
+    protected def iter = c.iterator
+    protected def fromIter(it: => Iterator[A]): C[A] = c.fromIterator(it)
+  }
+
+  /** Implementation of PolyTransforms for all generic collections */
+  implicit class IterablePolyTransforms[A, C[X] <: Iterable[X]](val c: Iterable[A] with FromIterator[C])
+  extends AnyVal with PolyTransforms[A, C] {
+    protected def iter = c.iterator
+    protected def fromIter[B](it: => Iterator[B]) = c.fromIterator(it)
+  }
+
+  /** Implementation of MonoTransformsForSeqs for all generic collections */
+  implicit class SeqMonoTransforms[A, C[X] <: Seq[X]](val c: Seq[A] with FromIterator[C])
+  extends AnyVal with MonoTransformsOfSeqs[A, C[A]] {
+    protected def iter = c.iterator
+    protected def fromIter(it: => Iterator[A]) = c.fromIterator(it)
+  }
+
+  /* --------- Concrete collection types ------------------------------- */
+
+  /** Concrete collection type: List */
+  sealed trait List[+A] extends Seq[A] with FromIterator[List] {
+    def isEmpty: Boolean
+    def head: A
+    def tail: List[A]
+    def iterator = new ListIterator[A](this)
+    def fromIterator[B](it: Iterator[B]): List[B] = List.fromIterator(it)
+    def apply(i: LengthType): A = {
+      require(!isEmpty)
+      if (i == 0) head else tail.apply(i - 1)
+    }
+    def length: LengthType =
+      if (isEmpty) 0 else 1 + tail.length
+  }
+
+  case class Cons[+A](x: A, xs: List[A]) extends List[A] {
+    def isEmpty = false
+    def head = x
+    def tail = xs
+  }
+
+  case object Nil extends List[Nothing] {
+    def isEmpty = true
+    def head = ???
+    def tail = ???
+  }
+
+  object List extends IterableFactory[List] {
+    def fromIterator[B](it: Iterator[B]): List[B] = it match {
+      case it: ListIterator[B] => it.toList
+      case _ => if (it.hasNext) Cons(it.next, fromIterator(it)) else Nil
+    }
+  }
+
+  class ListIterator[+A](xs: List[A]) extends Iterator[A] {
+    private[this] var current = xs
+    def hasNext = !current.isEmpty
+    def next = { val r = current.head; current = current.tail; r }
+    def toList = current
+  }
+
+  /** Concrete collection type: ArrayBuffer */
+  class ArrayBuffer[A] private (initElems: Array[AnyRef], initLength: LengthType) extends Seq[A] with FromIterator[ArrayBuffer] {
+    def this() = this(new Array[AnyRef](16), 0)
+    private var elems: Array[AnyRef] = initElems
+    private var start: LengthType = 0
+    private var limit: LengthType = initLength
+    def apply(i: LengthType) = elems(start + i).asInstanceOf[A]
+    def length = limit - start
+    def iterator = new ArrayBufferIterator[A](elems, start, length)
+    def fromIterator[B](it: Iterator[B]): ArrayBuffer[B] =
+      ArrayBuffer.fromIterator(it)
+    def +=(elem: A): this.type = {
+      if (limit == elems.length) {
+        if (start > 0) {
+          Array.copy(elems, start, elems, 0, length)
+          limit -= start
+          start = 0
+        }
+        else {
+          val newelems = new Array[AnyRef](limit * 2)
+          Array.copy(elems, 0, newelems, 0, limit)
+          elems = newelems
+        }
+      }
+      elems(limit) = elem.asInstanceOf[AnyRef]
+      limit += 1
+      this
+    }
+    def trimStart(n: LengthType): Unit = start += (n max 0)
+    override def toString = s"ArrayBuffer(${elems.slice(start, limit).mkString(", ")})"
+  }
+
+  object ArrayBuffer extends IterableFactory[ArrayBuffer] {
+    def fromIterator[B](it: Iterator[B]): ArrayBuffer[B] = it match {
+      case Iterator.Concat(fst: ArrayBufferIterator[_], snd: ArrayBufferIterator[_]) =>
+        val elems = new Array[AnyRef](fst.remaining + snd.remaining)
+        Array.copy(fst.elems, fst.start, elems, 0, fst.remaining)
+        Array.copy(snd.elems, snd.start, elems, fst.remaining, snd.remaining)
+        new ArrayBuffer(elems, elems.length)
+      case it @ Iterator.Partition(underlying, _, buf, _) =>
+        while (underlying.hasNext) it.distribute()
+        buf.asInstanceOf[ArrayBuffer[B]]
+      case it if it.remaining >= 0 =>
+        val elems = new Array[AnyRef](it.remaining)
+        for (i <- 0 until elems.length) elems(i) = it.next.asInstanceOf[AnyRef]
+        new ArrayBuffer[B](elems, elems.length)
+      case _ =>
+        val buf = new ArrayBuffer[B]
+        while (it.hasNext) buf += it.next
+        buf
+    }
+  }
+
+  class ArrayBufferIterator[A](val elems: Array[AnyRef], initStart: LengthType, length: LengthType) extends RandomAccessIterator[A] {
+    val limit: LengthType = length
+    def apply(n: LengthType) = elems(initStart + n).asInstanceOf[A]
+  }
+
+  /** Concrete collection type: View */
+
+  implicit class ViewOps[A](val v: View[A]) extends AnyVal with Ops[A] {
+    def iterator = v.iterator
+    def cache = collectAs(ArrayBuffer).view
+  }
+
+  implicit class ViewMonoTransforms[A](val v: View[A])
+  extends AnyVal with MonoTransforms[A, View[A]] {
+    protected def iter = v.iterator
+    protected def fromIter(it: => Iterator[A]): View[A] = it
+  }
+
+  implicit class ViewPolyTransforms[A](val v: View[A])
+  extends AnyVal with PolyTransforms[A, View] {
+    protected def iter = v.iterator
+    protected def fromIter[B](it: => Iterator[B]) = it
+  }
+
+  /** Concrete collection type: String */
+  implicit class StringOps(val s: String) extends AnyVal with Ops[Char] {
+    def iterator: Iterator[Char] = new RandomAccessIterator[Char] {
+      override val limit = s.length
+      def apply(n: LengthType) = s.charAt(n)
+    }
+  }
+
+  implicit class StringMonoTransforms(val s: String)
+  extends AnyVal with MonoTransformsOfSeqs[Char, String] {
+    protected def iter = StringOps(s).iterator
+    protected def fromIter(it: => Iterator[Char]) = {
+      val sb = new StringBuilder
+      for (ch <- it) sb.append(ch)
+      sb.toString
+    }
+  }
+
+  implicit class StringPolyTransforms(val s: String)
+  extends AnyVal with PolyTransforms[Char, Seq] {
+    protected def iter = StringOps(s).iterator
+    protected def fromIter[B](it: => Iterator[B]) = List.fromIterator(it)
+    def map(f: Char => Char): String = {
+      val sb = new StringBuilder
+      for (ch <- s) sb.append(f(ch))
+      sb.toString
+    }
+    def flatMap(f: Char => String) = {
+      val sb = new StringBuilder
+      for (ch <- s) sb.append(f(ch))
+      sb.toString
+    }
+    def ++(xs: CanIterate[Char]): String = {
+      val sb = new StringBuilder(s)
+      for (ch <- xs.iterator) sb.append(ch)
+      sb.toString
+    }
+    def ++(xs: String): String = s + xs
+  }
+
+/* ---------- Iterators --------------------------------------------------- */
+
+  /** A core Iterator class */
+  trait Iterator[+A] extends CanIterate[A] { self =>
+    def hasNext: Boolean
+    def next: A
+    def iterator = this
+    def reverse: Iterator[A] = {
+      var elems: List[A] = Nil
+      while (hasNext) elems = Cons(next, elems)
+      elems.iterator
+    }
+
+    /** If this iterator results from applying a transfomation to another iterator,
+     *  that other iterator, otherwise the iterator itself.
+     */
+    def underlying: Iterator[_] = this
+
+    /** If the number of elements still to be returned by this iterator is known,
+     *  that number, otherwise -1.
+     */
+    def remaining = -1
+  }
+
+  object Iterator {
+    val empty: Iterator[Nothing] = new Iterator[Nothing] {
+      def hasNext = false
+      def next = ???
+      override def remaining = 0
+    }
+    def apply[A](xs: A*): Iterator[A] = new RandomAccessIterator[A] {
+      override val limit = xs.length
+      def apply(n: LengthType) = xs(n)
+    }
+    def nextOnEmpty = throw new NoSuchElementException("next on empty iterator")
+
+    case class Map[A, B](override val underlying: Iterator[A], f: A => B) extends Iterator[B] {
+      def hasNext = underlying.hasNext
+      def next = f(underlying.next)
+      override def remaining = underlying.remaining
+    }
+    case class FlatMap[A, B](override val underlying: Iterator[A], f: A => CanIterate[B]) extends Iterator[B] {
+      private var myCurrent: Iterator[B] = Iterator.empty
+      private def current = {
+        while (!myCurrent.hasNext && underlying.hasNext)
+          myCurrent = f(underlying.next).iterator
+        myCurrent
+      }
+      def hasNext = current.hasNext
+      def next = current.next
+    }
+    case class Concat[A](override val underlying: Iterator[A], other: Iterator[A]) extends Iterator[A] {
+      private var myCurrent = underlying
+      private def current = {
+        if (!myCurrent.hasNext && myCurrent.eq(underlying)) myCurrent = other
+        myCurrent
+      }
+      def hasNext = current.hasNext
+      def next = current.next
+      override def remaining =
+        if (underlying.remaining >= 0 && other.remaining >= 0)
+          underlying.remaining + other.remaining
+        else -1
+    }
+    case class Partition[A](override val underlying: Iterator[A], p: A => Boolean, lookahead: ArrayBuffer[A], dual: ArrayBuffer[A]) extends Iterator[A] {
+      def distribute() = {
+        val elem = underlying.next
+        (if (p(elem)) lookahead else dual) += elem
+      }
+      final def hasNext: Boolean =
+        !lookahead.isEmpty || underlying.hasNext && { distribute(); hasNext }
+      final def next =
+        if (hasNext) {
+          val r = lookahead.head
+          lookahead.trimStart(1)
+          r
+        } else Iterator.nextOnEmpty
+    }
+    case class Drop[A](override val underlying: Iterator[A], n: LengthType) extends Iterator[A] {
+      var toSkip = n
+      def hasNext: Boolean = underlying.hasNext && (
+        toSkip == 0 || { underlying.next; toSkip -= 1; hasNext })
+      def next = if (hasNext) underlying.next else nextOnEmpty
+      override def remaining = (underlying.remaining - toSkip) max -1
+    }
+    case class Zip[A, B](override val underlying: Iterator[A], other: Iterator[B]) extends Iterator[(A, B)] {
+      def hasNext = underlying.hasNext && other.hasNext
+      def next = (underlying.next, other.next)
+      override def remaining = underlying.remaining min other.remaining
+    }
+    case class Reverse[A](override val underlying: RandomAccessIterator[A]) extends RandomAccessIterator[A] {
+      def apply(n: LengthType) = underlying.apply(underlying.limit - 1 - n)
+      def limit = underlying.remaining
+    }
+  }
+
+  trait RandomAccessIterator[+A] extends Iterator[A] { self =>
+    def apply(n: LengthType): A
+    def limit: LengthType
+    var start = 0
+    override def remaining = (limit - start) max 0
+    def hasNext = start < limit
+    def next: A = { val r = this(start); start += 1; r }
+    override def drop(n: LengthType): Iterator[A] = { start += (n max 0); this }
+    override def reverse: Iterator[A] = new Iterator.Reverse(this)
+  }
+}
+
+