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Add Tuple.mapKind method #22824

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Add Tuple.mapKind method #22824

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10 changes: 10 additions & 0 deletions library/src/scala/Tuple.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -83,6 +83,13 @@ sealed trait Tuple extends Product {
inline def map[F[_]](f: [t] => t => F[t]): Map[this.type, F] =
runtime.Tuples.map(this, f).asInstanceOf[Map[this.type, F]]

/** Given a tuple of form `(F[T1], F[T2], ..., F[Tn])` and a function from F[T] to G[T] for any T out of T1...Tn,
* returns a new tuple `(G[T1], G[T2], ..., G[Tn])`.
*/
inline def mapKind[F[_], G[_]](fk: [t <: Union[InverseMap[this.type, F]]] => F[t] => G[t]): MapKind[this.type, F, G] =
runtime.Tuples.map(this, fk.asInstanceOf).asInstanceOf[MapKind[this.type, F, G]]


/** Given a tuple `(a1, ..., am)`, returns the tuple `(a1, ..., an)` consisting
* of its first n elements.
*/
Expand Down Expand Up @@ -219,6 +226,9 @@ object Tuple {
case EmptyTuple => EmptyTuple
}

/** Converts a tuple `(F[T1], F[T2], ..., F[Tn])` to `(G[T1], G[T2], ..., G[Tn])` */
type MapKind[T <: Tuple, F[_], G[_]] = Map[InverseMap[T, F], G]

/** Implicit evidence. IsMappedBy[F][X] is present in the implicit scope iff
* X is a tuple for which each element's type is constructed via `F`. E.g.
* (F[A1], ..., F[An]), but not `(F[A1], B2, ..., F[An])` where B2 does not
Expand Down
39 changes: 39 additions & 0 deletions tests/run/Tuple-mapKind.scala
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Original file line number Diff line number Diff line change
@@ -0,0 +1,39 @@
object Test {

type Tup = (Int, Double, Boolean, String)

def main(args: Array[String]): Unit = {

val headOption: [x] => Seq[x] => Option[x] = [x] => (seq: Seq[x]) => seq.headOption
val firstTruthy: [T <: Tuple.Union[Tup]] => Seq[T] => Option[T] = [T <: Tuple.Union[Tup]] =>
(seq: Seq[T]) => seq.find {
case x: Int => x > 0
case x: Double => x > 0.0
case x: Boolean => x
case x: String => x.nonEmpty
}

val seqTuple: Tuple.Map[Tup, Seq] = (Vector(0, 1), Seq.empty, List(false, true), Vector("4", "44"))
val expectHeadOptionTuple: Tuple.Map[Tup, Option] = (Some(0), None, Some(false), Some("4"))
val expectFirstTruthyTuple: Tuple.Map[Tup, Option] = (Some(1), None, Some(true), Some("4"))

assert(
EmptyTuple.mapKind[Seq, Option](headOption) == EmptyTuple
)
assert(
EmptyTuple.mapKind[Seq, Option](firstTruthy) == EmptyTuple
)
assert(
(List("", "1") *: EmptyTuple).mapKind[Seq, Option](headOption) == (Some("") *: EmptyTuple)
)
assert(
(List("", "1") *: EmptyTuple).mapKind[Seq, Option](firstTruthy) == (Some("1") *: EmptyTuple)
)
assert(
seqTuple.mapKind[Seq, Option](headOption) == expectHeadOptionTuple
)
assert(
seqTuple.mapKind[Seq, Option](firstTruthy) == expectFirstTruthyTuple
)
}
}
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Got the following pickling comparison error (diff before-pickling.txt after-pickling.txt)

172,173c172,173
<             :[T <: scala.Int | scala.Double | (scala.Boolean | String)] => (seq: Seq[T]) => scala.Option[T]>@
<               tests/run/Tuple-mapKind.scala<261..458>
---
>             :[T <: scala.Tuple.Fold[(scala.Int, scala.Double, scala.Boolean, String), scala.Nothing, [x, y] =>> x | y]
>               ] => (seq: Seq[T]) => scala.Option[T]>@tests/run/Tuple-mapKind.scala<261..458>
404,405c404,405
<                         <firstTruthy:[T <: scala.Int | scala.Double | (scala.Boolean | scala.Predef.String)] => (x$1:
<                           Seq[T]) => scala.Option[T]>@tests/run/Tuple-mapKind.scala<889..900>
---
>                         <firstTruthy:[T <: scala.Tuple.Fold[Test.Tup, scala.Nothing, [x, y] =>> x | y]] => (x$1: Seq[T]
>                           ) => scala.Option[T]>@tests/run/Tuple-mapKind.scala<889..900>
614,615c614,615
<                         <firstTruthy:[T <: scala.Int | scala.Double | (scala.Boolean | scala.Predef.String)] => (x$1:
<                           Seq[T]) => scala.Option[T]>@tests/run/Tuple-mapKind.scala<1106..1117>
---
>                         <firstTruthy:[T <: scala.Tuple.Fold[Test.Tup, scala.Nothing, [x, y] =>> x | y]] => (x$1: Seq[T]
>                           ) => scala.Option[T]>@tests/run/Tuple-mapKind.scala<1106..1117>
678,682c678,679
<                                   scala.Tuple.InverseMap[
<                                     (seqTuple : (Seq[scala.Int], Seq[scala.Double], Seq[scala.Boolean],
<                                       Seq[scala.Predef.String])),
<                                   F],
<                                 scala.Nothing, [x, y] =>> x | y]
---
>                                   scala.Tuple.InverseMap[(seqTuple : scala.Tuple.Map[Test.Tup, scala.package.Seq]), F],
>                                   scala.Nothing, [x, y] =>> x | y]
685,689c682,683
<                                   scala.Tuple.InverseMap[
<                                     (seqTuple : (Seq[scala.Int], Seq[scala.Double], Seq[scala.Boolean],
<                                       Seq[scala.Predef.String])),
<                                   F],
<                                 G]
---
>                                   scala.Tuple.InverseMap[(seqTuple : scala.Tuple.Map[Test.Tup, scala.package.Seq]), F],
>                                   G]
696,699c690,691
<                               scala.Tuple.InverseMap[
<                                 (seqTuple : (Seq[scala.Int], Seq[scala.Double], Seq[scala.Boolean],
<                                   Seq[scala.Predef.String])),
<                               scala.package.Seq],
---
>                               scala.Tuple.InverseMap[(seqTuple : scala.Tuple.Map[Test.Tup, scala.package.Seq]),
>                                 scala.package.Seq],
703,706c695,696
<                               scala.Tuple.InverseMap[
<                                 (seqTuple : (Seq[scala.Int], Seq[scala.Double], Seq[scala.Boolean],
<                                   Seq[scala.Predef.String])),
<                               scala.package.Seq],
---
>                               scala.Tuple.InverseMap[(seqTuple : scala.Tuple.Map[Test.Tup, scala.package.Seq]),
>                                 scala.package.Seq],
749,753c739,740
<                                   scala.Tuple.InverseMap[
<                                     (seqTuple : (Seq[scala.Int], Seq[scala.Double], Seq[scala.Boolean],
<                                       Seq[scala.Predef.String])),
<                                   F],
<                                 scala.Nothing, [x, y] =>> x | y]
---
>                                   scala.Tuple.InverseMap[(seqTuple : scala.Tuple.Map[Test.Tup, scala.package.Seq]), F],
>                                   scala.Nothing, [x, y] =>> x | y]
756,760c743,744
<                                   scala.Tuple.InverseMap[
<                                     (seqTuple : (Seq[scala.Int], Seq[scala.Double], Seq[scala.Boolean],
<                                       Seq[scala.Predef.String])),
<                                   F],
<                                 G]
---
>                                   scala.Tuple.InverseMap[(seqTuple : scala.Tuple.Map[Test.Tup, scala.package.Seq]), F],
>                                   G]
767,770c751,752
<                               scala.Tuple.InverseMap[
<                                 (seqTuple : (Seq[scala.Int], Seq[scala.Double], Seq[scala.Boolean],
<                                   Seq[scala.Predef.String])),
<                               scala.package.Seq],
---
>                               scala.Tuple.InverseMap[(seqTuple : scala.Tuple.Map[Test.Tup, scala.package.Seq]),
>                                 scala.package.Seq],
774,777c756,757
<                               scala.Tuple.InverseMap[
<                                 (seqTuple : (Seq[scala.Int], Seq[scala.Double], Seq[scala.Boolean],
<                                   Seq[scala.Predef.String])),
<                               scala.package.Seq],
---
>                               scala.Tuple.InverseMap[(seqTuple : scala.Tuple.Map[Test.Tup, scala.package.Seq]),
>                                 scala.package.Seq],
782,783c762,763
<                         <firstTruthy:[T <: scala.Int | scala.Double | (scala.Boolean | scala.Predef.String)] => (x$1:
<                           Seq[T]) => scala.Option[T]>@tests/run/Tuple-mapKind.scala<1293..1304>
---
>                         <firstTruthy:[T <: scala.Tuple.Fold[Test.Tup, scala.Nothing, [x, y] =>> x | y]] => (x$1: Seq[T]
>                           ) => scala.Option[T]>@tests/run/Tuple-mapKind.scala<1293..1304>

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