Go back to using Traversable instead of Iterable

This is a no-op for 2.13, as Traversable is a (deprecated) alias for
Iterable. For 2.10-2.12, this ensures that the signatures don't change
due to cross-building with 2.13.

src/main/scala/org/scalacheck/Arbitrary.scala

@@ -357,17 +357,17 @@ private[scalacheck] sealed trait ArbitraryLowPriority {
     Arbitrary(Gen.oneOf(arbitrary[T].map(Success(_)), arbitrary[Throwable].map(Failure(_))))
 
   /** Arbitrary instance of any [[org.scalacheck.util.Buildable]] container
-   *  (such as lists, arrays, lazy lists, etc). The maximum size of the container
+   *  (such as lists, arrays, streams / lazy lists, etc). The maximum size of the container
    *  depends on the size generation parameter. */
   implicit def arbContainer[C[_],T](implicit
-    a: Arbitrary[T], b: Buildable[T,C[T]], t: C[T] => Iterable[T]
+    a: Arbitrary[T], b: Buildable[T,C[T]], t: C[T] => Traversable[T]
   ): Arbitrary[C[T]] = Arbitrary(buildableOf[C[T],T](arbitrary[T]))
 
   /** Arbitrary instance of any [[org.scalacheck.util.Buildable]] container
    *  (such as maps). The maximum size of the container depends on the size
    *  generation parameter. */
   implicit def arbContainer2[C[_,_],T,U](implicit
-    a: Arbitrary[(T,U)], b: Buildable[(T,U),C[T,U]], t: C[T,U] => Iterable[(T,U)]
+    a: Arbitrary[(T,U)], b: Buildable[(T,U),C[T,U]], t: C[T,U] => Traversable[(T,U)]
   ): Arbitrary[C[T,U]] = Arbitrary(buildableOf[C[T,U],(T,U)](arbitrary[(T,U)]))
 
   implicit def arbEnum[A <: java.lang.Enum[A]](implicit A: reflect.ClassTag[A]): Arbitrary[A] = {

src/main/scala/org/scalacheck/Gen.scala

@@ -577,55 +577,55 @@ object Gen extends GenArities with GenVersionSpecific {
 
   //// List Generators ////
 
-  /** Generates a container of any Iterable type for which there exists an
+  /** Generates a container of any Traversable type for which there exists an
    *  implicit [[org.scalacheck.util.Buildable]] instance. The elements in the
    *  container will be generated by the given generator. The size of the
    *  generated container is limited by `n`. Depending on what kind of container
    *  that is generated, the resulting container may contain fewer elements than
    *  `n`, but not more. If the given generator fails generating a value, the
    *  complete container generator will also fail. */
   def buildableOfN[C,T](n: Int, g: Gen[T])(implicit
-    evb: Buildable[T,C], evt: C => Iterable[T]
+    evb: Buildable[T,C], evt: C => Traversable[T]
   ): Gen[C] =
-    sequence[C,T](Iterable.fill(n)(g)) suchThat { c =>
+    sequence[C,T](Traversable.fill(n)(g)) suchThat { c =>
       // TODO: Can we guarantee c.size == n (See issue #89)?
       c.forall(g.sieveCopy)
     }
 
-  /** Generates a container of any Iterable type for which there exists an
+  /** Generates a container of any Traversable type for which there exists an
    *  implicit [[org.scalacheck.util.Buildable]] instance. The elements in the
    *  container will be generated by the given generator. The size of the
    *  container is bounded by the size parameter used when generating values. */
   def buildableOf[C,T](g: Gen[T])(implicit
-    evb: Buildable[T,C], evt: C => Iterable[T]
+    evb: Buildable[T,C], evt: C => Traversable[T]
   ): Gen[C] =
     sized(s => choose(0, s max 0).flatMap(buildableOfN[C,T](_,g))) suchThat { c =>
       if (c == null) g.sieveCopy(null) else c.forall(g.sieveCopy)
     }
 
-  /** Generates a non-empty container of any Iterable type for which there
+  /** Generates a non-empty container of any Traversable type for which there
    *  exists an implicit [[org.scalacheck.util.Buildable]] instance. The
    *  elements in the container will be generated by the given generator. The
    *  size of the container is bounded by the size parameter used when
    *  generating values. */
   def nonEmptyBuildableOf[C,T](g: Gen[T])(implicit
-    evb: Buildable[T,C], evt: C => Iterable[T]
+    evb: Buildable[T,C], evt: C => Traversable[T]
   ): Gen[C] =
     sized(s => choose(1, s max 1).flatMap(buildableOfN[C,T](_,g))) suchThat(_.size > 0)
 
   /** A convenience method for calling `buildableOfN[C[T],T](n,g)`. */
   def containerOfN[C[_],T](n: Int, g: Gen[T])(implicit
-    evb: Buildable[T,C[T]], evt: C[T] => Iterable[T]
+    evb: Buildable[T,C[T]], evt: C[T] => Traversable[T]
   ): Gen[C[T]] = buildableOfN[C[T],T](n,g)
 
   /** A convenience method for calling `buildableOf[C[T],T](g)`. */
   def containerOf[C[_],T](g: Gen[T])(implicit
-    evb: Buildable[T,C[T]], evt: C[T] => Iterable[T]
+    evb: Buildable[T,C[T]], evt: C[T] => Traversable[T]
   ): Gen[C[T]] = buildableOf[C[T],T](g)
 
   /** A convenience method for calling `nonEmptyBuildableOf[C[T],T](g)`. */
   def nonEmptyContainerOf[C[_],T](g: Gen[T])(implicit
-    evb: Buildable[T,C[T]], evt: C[T] => Iterable[T]
+    evb: Buildable[T,C[T]], evt: C[T] => Traversable[T]
   ): Gen[C[T]] = nonEmptyBuildableOf[C[T],T](g)
 
   /** Generates a list of random length. The maximum length depends on the
@@ -656,7 +656,7 @@ object Gen extends GenArities with GenVersionSpecific {
    *  is equal to calling <code>containerOfN[Map,T,U](n,g)</code>. */
   def mapOfN[T,U](n: Int, g: Gen[(T,U)]) = buildableOfN[Map[T,U],(T,U)](n,g)
 
-  /** Generates an infinite lazy list. */
+  /** Generates an infinite stream. */
   def infiniteStream[T](g: => Gen[T]): Gen[Stream[T]] = {
     def unfold[A, S](z: S)(f: S => Option[(A, S)]): Stream[A] = f(z) match {
       case Some((h, s)) => h #:: unfold(s)(f)

src/main/scala/org/scalacheck/Shrink.scala

@@ -30,7 +30,7 @@ object Shrink extends ShrinkLowPriority {
   import LazyList.{cons, empty}
   import scala.collection._
 
-  /** Interleaves two lazy lists */
+  /** Interleaves two streams / lazy lists */
   private def interleave[T](xs: LazyList[T], ys: LazyList[T]): LazyList[T] =
     if(xs.isEmpty) ys
     else if(ys.isEmpty) xs
@@ -45,12 +45,12 @@ object Shrink extends ShrinkLowPriority {
   def shrink[T](x: T)(implicit s: Shrink[T]): LazyList[T] = s.shrink(x)
 
   /** Shrink a value, but also return the original value as the first element in
-   *  the resulting lazy list */
+   *  the resulting stream / lazy list */
   def shrinkWithOrig[T](x: T)(implicit s: Shrink[T]): LazyList[T] =
     cons(x, s.shrink(x))
 
   /** Shrink instance of container */
-  implicit def shrinkContainer[C[_],T](implicit v: C[T] => Iterable[T], s: Shrink[T],
+  implicit def shrinkContainer[C[_],T](implicit v: C[T] => Traversable[T], s: Shrink[T],
     b: Buildable[T,C[T]]
   ): Shrink[C[T]] = Shrink { xs: C[T] =>
     val ys = v(xs)
@@ -59,7 +59,7 @@ object Shrink extends ShrinkLowPriority {
   }
 
   /** Shrink instance of container2 */
-  implicit def shrinkContainer2[C[_,_],T,U](implicit v: C[T,U] => Iterable[(T,U)], s: Shrink[(T,U)],
+  implicit def shrinkContainer2[C[_,_],T,U](implicit v: C[T,U] => Traversable[(T,U)], s: Shrink[(T,U)],
     b: Buildable[(T,U),C[T,U]]
   ): Shrink[C[T,U]] = Shrink { xs: C[T,U] =>
     val ys = v(xs)

src/main/scala/org/scalacheck/util/Buildable.scala

@@ -26,8 +26,8 @@ trait Buildable[T,C] extends Serializable {
   * Factory instances implementing Serializable, so that the objects capturing those can be
   * serializable too.
   */
+// Names are `..CanBuildFrom` for binary compatibility. Change to `..Factory` in a major release.
 object SerializableCanBuildFroms {
-  // Names are `..CanBuildFrom` for binary compatibility. Change to `..Factory` in a major release.
   implicit def listCanBuildFrom[T]: Factory[T, List[T]] = ScalaVersionSpecific.listFactory
   implicit def bitsetCanBuildFrom[T]: Factory[Int, BitSet] = ScalaVersionSpecific.bitsetFactory
   implicit def mapCanBuildFrom[T, U]: Factory[(T, U), Map[T, U]] = ScalaVersionSpecific.mapFactory
@@ -41,7 +41,7 @@ object Buildable {
     }
 
   import java.util.ArrayList
-  implicit def buildableArrayList[T] = new Buildable[T,ArrayList[T]] {
+  implicit def buildableArrayList[T]: Buildable[T, ArrayList[T]] = new Buildable[T,ArrayList[T]] {
     def builder = new ArrayListBuilder[T]
   }
 

src/test/scala/org/scalacheck/ShrinkSpecification.scala

@@ -105,7 +105,7 @@ object ShrinkSpecification extends Properties("Shrink") {
 
   /* Ensure that shrink[T] terminates. (#244)
    *
-   * Let's say shrinking "terminates" when the lazy list of values
+   * Let's say shrinking "terminates" when the stream / lazy list of values
    * becomes empty. We can empirically determine the longest possible
    * sequence for a given type before termination. (Usually this
    * involves using the type's MinValue.)

src/test/scala/org/scalacheck/util/BuildableSpecification.scala

@@ -17,7 +17,7 @@ import ScalaVersionSpecific._
 object BuildableSpecification {
   def container[C[_]](implicit
     evb: Buildable[String, C[String]],
-    evt: C[String] => Iterable[String]
+    evt: C[String] => Traversable[String]
   ) = Gen.containerOf[C, String](Gen.alphaStr)
 
   implicit val listGen: Gen[List[String]] = container[List]