Add implicit conversion from IArray.type to Factory

old style conversion so no language import is needed.

When `into` is stabilized, then possibly `Factory` can be converted
to an `into` trait, and the conversion turned into the new `given Conversion` style

Author: bishabosha

library/src/scala/IArray.scala

@@ -3,7 +3,9 @@ import reflect.ClassTag
 
 import language.experimental.captureChecking
 
-import scala.collection.{LazyZip2, SeqView, Searching, Stepper, StepperShape}
+import scala.annotation.experimental
+
+import scala.collection.{LazyZip2, SeqView, Searching, Stepper, StepperShape, Factory}
 import scala.collection.immutable.ArraySeq
 import scala.collection.mutable.{ArrayBuilder, Builder}
 
@@ -14,6 +16,19 @@ opaque type IArray[+T] = Array[? <: T]
  */
 object IArray:
 
+  // OLD style implicit conversion so no import is needed at use-site.
+  // once `into` feature is made stable, we could make `Factory` an `into` trait, and
+  // change this to the new style `given Conversion`.
+  /** Provides an implicit conversion from the IArray object to a collection Factory */
+  @experimental
+  implicit def convertIArrayToFactory[A : ClassTag](@annotation.unused asFactory: IArray.type): Factory[A, IArray[A]] =
+    // copied from ArrayFactory, i guess its possible to capture a factory?
+    @SerialVersionUID(3L)
+    class ConcreteIArrayFactory extends Factory[A, IArray[A]] with Serializable:
+      def fromSpecific(it: IterableOnce[A]^): IArray[A] = IArray.from[A](it)
+      def newBuilder: Builder[A, IArray[A]] = IArray.newBuilder[A]
+    ConcreteIArrayFactory()
+
   /** The selection operation on an immutable array.
     *
     *  @param arr the immutable array

tests/run-tasty-inspector/stdlibExperimentalDefinitions.scala

@@ -98,6 +98,9 @@ val experimentalDefinitionInLibrary = Set(
 
   // New feature: Erased trait
   "scala.compiletime.Erased",
+
+  // New API: IArray Factory conversion
+  "scala.IArray$package$.IArray$.convertIArrayToFactory",
 )
 
 

tests/run/IArrayOps-experimental-Factory.scala

@@ -0,0 +1,16 @@
+//> using options -experimental
+
+import scala.collection.Factory
+
+@main def Test: Unit =
+  val explicit: Factory[Int, IArray[Int]] = IArray.convertIArrayToFactory[Int](IArray)
+  val contextual: Factory[Int, IArray[Int]] = IArray: Factory[Int, IArray[Int]]
+
+  assert(explicit.getClass() == contextual.getClass()) // default is same implementation
+
+  val convertFromList = List(1,2,3).to(IArray)
+  val ev: IArray[Int] = convertFromList
+
+  assert(convertFromList.getClass == IArray(1,2,3).getClass())
+
+  assert(ev.sameElements(Vector(1,2,3)))