Add zip on tuples

Author: anatoliykmetyuk

library/src/scala/Tuple.scala

@@ -33,6 +33,8 @@ sealed trait Tuple extends Any {
   inline def size[This >: this.type <: Tuple]: Size[This] =
     DynamicTuple.dynamicSize(this)
 
+  inline def zip[This >: this.type <: Tuple, T2 <: Tuple](t2: T2): Zip[This, T2] =
+    DynamicTuple.dynamicZip(this, t2)
 }
 
 object Tuple {
@@ -74,6 +76,12 @@ object Tuple {
     case h *: t => F[h] *: Map[t, F]
   }
 
+  type Zip[T1 <: Tuple, T2 <: Tuple] <: Tuple = (T1, T2) match {
+    case (h1 *: t1, h2 *: t2) => (h1, h2) *: Zip[t1, t2]
+    case (Unit, _) => Unit
+    case (_, Unit) => Unit
+  }
+
   /** Convert an array into a tuple of unknown arity and types */
   def fromArray[T](xs: Array[T]): Tuple = {
     val xs2 = xs match {

library/src/scala/runtime/DynamicTuple.scala

@@ -1,10 +1,6 @@
 package scala.runtime
 
-import scala.Tuple.Concat
-import scala.Tuple.Size
-import scala.Tuple.Head
-import scala.Tuple.Tail
-import scala.Tuple.Elem
+import scala.Tuple.{ Concat, Size, Head, Tail, Elem, Zip }
 
 object DynamicTuple {
   inline val MaxSpecialized = 22
@@ -253,6 +249,14 @@ object DynamicTuple {
     res.asInstanceOf[Result]
   }
 
+  def dynamicZip[This <: Tuple, T2 <: Tuple](t1: This, t2: T2): Zip[This, T2] = {
+    if (t1.size == 0 || t2.size == 0) ().asInstanceOf[Zip[This, T2]]
+    else Tuple.fromArray(
+      t1.asInstanceOf[Product].productIterator.zip(
+      t2.asInstanceOf[Product].productIterator).toArray
+    ).asInstanceOf[Zip[This, T2]]
+  }
+
   def consIterator(head: Any, tail: Tuple): Iterator[Any] =
     Iterator.single(head) ++ tail.asInstanceOf[Product].productIterator
 

tests/run/tuple-ops.check

@@ -0,0 +1,5 @@
+((1,4),(2,5),(3,6))
+((1,7),(2,8))
+((7,1),(8,2))
+()
+()

tests/run/tuple-ops.scala

@@ -0,0 +1,18 @@
+val a: (1, 2, 3) = (1, 2, 3)
+val b: (4, 5, 6) = (4, 5, 6)
+val c: (7, 8) = (7, 8)
+val d: Unit = ()
+
+val r1: ((1, 4), (2, 5), (3, 6)) = a.zip(b)
+val r2: ((1, 7), (2, 8)) = a.zip(c)
+val r3: ((7, 1), (8, 2)) = c.zip(a)
+val r4: Unit = d.zip(a)
+val r5: Unit = a.zip(d)
+
+@main def Test = List(
+  r1,
+  r2,
+  r3,
+  r4,
+  r5)
+.foreach(println)