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Widen parLiftN's constraint to NonEmptyParallel #4702

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c04ea66
Widen parLiftN's constraint to NonEmptyParallel
kubukoz Jan 20, 2025
eb5a531
new base who dis?
kubukoz Jan 20, 2025
547dd85
mima hacks
kubukoz Jan 21, 2025
2d82b53
proper mima workaround
kubukoz Jan 21, 2025
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2 changes: 1 addition & 1 deletion build.sbt
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
ThisBuild / tlBaseVersion := "2.12"
ThisBuild / tlBaseVersion := "2.13"
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fyi: #4704

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Actually, this PR should bump to 2.14. It's making source-breaking changes and forwards binary-breaking changes, with respect to Cats v2.13.x so we need to bump the minor to reflect that.

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How are the changes source-breaking?

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@kubukoz , I'm wondering too: #4704 (comment)
Perhaps there's some mystery to be unraveled :)

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How are the changes source-breaking?

This code compiles in 2.13, but won't after these changes.

object syntax extends cats.syntax.FunctionApplySyntax
import syntax.*
fn.liftN(...)

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hmm I wonder if we can make the old syntax trait extend the new. Still, if someone hand-picks their imports they'll be source-broken. Do we care about this use case?

I don't suppose we'll release a 0.14 soon...

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@armanbilge armanbilge Jan 22, 2025 •
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Still, if someone hand-picks their imports they'll be source-broken. Do we care about this use case?

Yes, that's the point. Whenever we make any change like this, it is technically source-breaking.

To clarify, I'm not saying we should avoid source-breaking changes: this makes it impossible to add new features. What I'm saying is that, because these typical changes are source-breaking, we have to bump the base version.


val scalaCheckVersion = "1.18.1"

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2 changes: 1 addition & 1 deletion core/src/main/scala/cats/syntax/apply.scala
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Expand Up @@ -22,7 +22,7 @@
package cats
package syntax

trait ApplySyntax extends TupleSemigroupalSyntax with FunctionApplySyntax {
trait ApplySyntax extends TupleSemigroupalSyntax with FunctionApplySyntax with FunctionApplySyntax2 {
@deprecated("Kept for binary compatibility", "2.10.0")
final def catsSyntaxApply[F[_], A](fa: F[A], F: Apply[F]): Apply.Ops[F, A] =
new Apply.Ops[F, A] {
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42 changes: 37 additions & 5 deletions project/Boilerplate.scala
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Expand Up @@ -33,6 +33,7 @@ object Boilerplate {
GenParallelArityFunctions2,
GenFoldableArityFunctions,
GenFunctionSyntax,
GenFunctionSyntax2,
GenTupleParallelSyntax,
GenTupleShowInstances,
GenTupleMonadInstances,
Expand Down Expand Up @@ -624,12 +625,9 @@ object Boilerplate {
|package cats
|package syntax
|
|import cats.Functor
|import cats.Semigroupal
|
|trait FunctionApplySyntax {
| implicit def catsSyntaxFunction1Apply[T, A0](f: Function1[A0, T]): Function1ApplyOps[T, A0] = new Function1ApplyOps(f)
- implicit def catsSyntaxFunction${arity}Apply[T, ${`A..N`}](f: $function): Function${arity}ApplyOps[T, ${`A..N`}] = new Function${arity}ApplyOps(f)
| def catsSyntaxFunction1Apply[T, A0](f: Function1[A0, T]): Function1ApplyOps[T, A0] = new Function1ApplyOps(f)
- def catsSyntaxFunction${arity}Apply[T, ${`A..N`}](f: $function): Function${arity}ApplyOps[T, ${`A..N`}] = new Function${arity}ApplyOps(f)
|}
|
|private[syntax] final class Function1ApplyOps[T, A0](private val f: Function1[A0, T]) extends AnyVal with Serializable {
Expand All @@ -644,4 +642,38 @@ object Boilerplate {
"""
}
}

object GenFunctionSyntax2 extends Template {
def filename(root: File) = root / "cats" / "syntax" / "FunctionApplySyntax2.scala"

override def range = 2 to maxArity

def content(tv: TemplateVals) = {
import tv._

val function = s"Function$arity[${`A..N`}, T]"

val typedParams = synVals.zip(synTypes).map { case (v, t) => s"$v: F[$t]" }.mkString(", ")

block"""
|package cats
|package syntax
|
|trait FunctionApplySyntax2 {
| implicit def catsSyntaxFunction1Apply2[T, A0](f: Function1[A0, T]): Function1ApplyOps2[T, A0] = new Function1ApplyOps2(f)
- implicit def catsSyntaxFunction${arity}Apply2[T, ${`A..N`}](f: $function): Function${arity}ApplyOps2[T, ${`A..N`}] = new Function${arity}ApplyOps2(f)
|}
|
|private[syntax] final class Function1ApplyOps2[T, A0](private val f: Function1[A0, T]) extends AnyVal with Serializable {
| def liftN[F[_]: Functor](a0: F[A0]): F[T] = Functor[F].map(a0)(f)
| def parLiftN[F[_]: Functor](a0: F[A0]): F[T] = Functor[F].map(a0)(f)
|}
|
-private[syntax] final class Function${arity}ApplyOps2[T, ${`A..N`}](private val f: $function) extends AnyVal with Serializable {
- def liftN[F[_]: Functor: Semigroupal]($typedParams): F[T] = Semigroupal.map$arity(${`a..n`})(f)
- def parLiftN[F[_]: NonEmptyParallel]($typedParams): F[T] = Parallel.parMap$arity(${`a..n`})(f)
-}
"""
}
}
}
24 changes: 24 additions & 0 deletions tests/shared/src/test/scala/cats/tests/SyntaxSuite.scala
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Expand Up @@ -345,6 +345,30 @@ object SyntaxSuite {
result3: F[T]
}

def testParLiftNNonEmpty[F[_]: NonEmptyParallel: Functor, A, B, C, T] = {
val fa = mock[F[A]]
val fb = mock[F[B]]
val fc = mock[F[C]]

val fapply1 = mock[A => T]

val result1 = fapply1.parLiftN(fa)

result1: F[T]

val fapply2 = mock[(A, B) => T]

val result2 = fapply2.parLiftN(fa, fb)

result2: F[T]

val fapply3 = mock[(A, B, C) => T]

val result3 = fapply3.parLiftN(fa, fb, fc)

result3: F[T]
}

def testParallelBi[M[_], F[_], T[_, _]: Bitraverse, A, B, C, D](implicit P: Parallel.Aux[M, F]): Unit = {
val tab = mock[T[A, B]]
val f = mock[A => M[C]]
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