Crossbuild scala-3 #206

Daenyth · 2021-07-14T16:41:06Z

This includes the Traverse derivation, but not with the same api, and doesn't include the recursion scheme derivation
I've tried to keep api changes to a minimum
The various data types apply/un methods in scala3 use .isInstanceOf directly - this might be slower than the scala2 fastCast macro
reftree now builds on all versions, but has source code only in 2.12, due to s̵͎̿̾b̶͚̜͝t̸̮̑ ̷̡̀r̶̭̒̎e̵̢̮͝a̴̜͑s̸̤̈́̏ò̸̭n̸̨̨̋s̸̤̅

Daenyth · 2021-07-14T20:47:50Z

athema/src/main/scala/higherkindness/athema/expr.scala

+      def traverse[G[_]: Applicative, A, B](
+          fa: Expr[V, A]
+      )(f: A => G[B]): G[Expr[V, B]] = fa match {
+        case v: Var[V, A]   => (v.asInstanceOf[Expr[V, B]]).pure[G]


scala3 reports this match as non-exhaustive with the @unchecked annotations in there.

Daenyth · 2021-07-14T20:49:56Z

athema/src/main/scala/higherkindness/athema/parser.scala

@@ -45,7 +45,7 @@ object ExprParser {
          case TSub      => shunt(op, 1).flatMap(_.traverse(enqueue))
          case TProd     => shunt(op, 2).flatMap(_.traverse(enqueue))
          case TDiv      => shunt(op, 2).flatMap(_.traverse(enqueue))
-        }).as(tail.asLeft)
+        }).map(_ => tail.asLeft)


as doesn't resolve, for some reason, in scala3. No idea why.

I think it was proposed, at some point, as a replacement for the @ in pattern matching. I had some comments about that.

Daenyth · 2021-07-14T20:52:28Z

build.sbt

+    // 'nowarn' doesn't work on scala3 yet, make warnings not fatal.
+    scalacOptions --= on(3)("-Xfatal-warnings").value


📝 This is pretty important

Daenyth · 2021-07-14T20:53:25Z

modules/core/src/main/scala-2/higherkindness/droste/data/AttrF.scala

+import higherkindness.droste.data.prelude._
+import higherkindness.droste.util.DefaultTraverse


I ran into issues with things not resolving using relative imports; I'll double check whether this is still needed now that everything compiles.

Edit: it is, don't know why

Hm... I thought we had a scalafix rule to prevent relative imports to be used, and always use absolute ones...

Daenyth · 2021-07-14T20:54:09Z

modules/core/src/main/scala-3/higherkindness/droste/data/Attr.scala

+  def apply[F[_], A](f: (A, F[Attr[F, A]])): Attr[F, A]         = f.asInstanceOf
+  def un[F[_], A](f: Attr[F, A]): (A, F[Attr[F, A]])            = f.asInstanceOf


For this and the other data types, the main difference is the apply/un things.

I might try to reduce some of the duplication, but we'll see if that proves worthwhile

Daenyth · 2021-07-14T20:58:53Z

modules/core/src/main/scala/higherkindness/droste/basis.scala

@@ -160,16 +181,22 @@ private[droste] sealed trait FloatingBasisInstances0[H[F[_], A] >: Basis[F, A]]
 private[droste] sealed trait FloatingBasisSolveInstances {
  import Basis.Solve

-  implicit val drosteSolveFix: Solve.Aux[Fix, λ[(F[_], α) => F[α]]] = null
-  implicit def drosteSolveAttr[A]: Solve.Aux[Attr[*[_], A], AttrF[*[_], A, *]] =
+  implicit val drosteSolveFix: Solve.Aux[Fix, ({ type L[F[_], A] = F[A] })#L] =


I had to desugar the type lambdas here because scala3's kind-projector syntax support doesn't work for type lambdas including higher-kinded types

Daenyth · 2021-07-14T20:59:29Z

modules/core/src/main/scala/higherkindness/droste/data/Mu.scala

+    new (Algebra[F, *] ~> Id) {
+      def apply[A](fa: Algebra[F, A]): Id[A] = Mu.this.apply(fa)
+    }


λ values aren't supported by scala3's -Ykind-projector support, so I had to desugar those as well.

Daenyth · 2021-07-14T21:01:21Z

modules/tests/src/test/scala-2.13+/higherkindness/droste/tests/SchemePartialBasisTests.scala

@@ -96,7 +98,7 @@ class SchemePartialBasisTests extends Properties("SchemePartialBasis") {
      if (n > 0) Mu(Some(expected(n - 1)))
      else Mu(None: Option[Mu[Option]])

-    forAll((n: Int Refined Less[W.`100`.T]) => f(n) ?= expected(n))
+    forAll((n: Int Refined Less[100]) => f(n) ?= expected(n))


In scala3, the W witness syntax isn't supported, so I moved these to src/test/scala-2.13+ and used the literal type syntax instead.

Thanks to Rob Norris (as always) for help on that;
https://github.com/tpolecat/skunk/blob/main/build.sbt#L64-L73

Daenyth · 2021-07-14T21:01:47Z

modules/tests/src/test/scala/higherkindness/droste/examples/histo/change.scala

@@ -167,10 +154,10 @@ object MakeChange {

  val makeChangeAlgebra: CVAlgebra[Nat, Set[List[Coin]]] = CVAlgebra {
    case Next(attr) =>
-      val given = fromNat(attr.forget) + 1
+      val _given = fromNat(attr.forget) + 1


Can't use given as an identifier name in scala3

Daenyth · 2021-07-14T21:02:01Z

modules/tests/src/test/scala/higherkindness/droste/examples/pro/SmallPost.scala

@@ -29,18 +29,20 @@ final class SmallPost extends Properties("SmallPost") {
        }
    }

-  implicit def streamFEmbed[A] = new Embed[StreamF[A, *], LazyList[A]] {
+  implicit def streamFEmbed[A]: Embed[StreamF[A, *], LazyList[A]] = new Embed[StreamF[A, *], LazyList[A]] {


Implicit vals must have types annotated

pepegar

Terrific job @Daenyth, thank you very much!

pepegar · 2021-07-19T09:56:57Z

build.sbt

-        ).map(_ % "test"))
+        ).map(_ % "test"),
+    // 'nowarn' doesn't work on scala3 yet, make warnings not fatal.
+    scalacOptions --= on(3)("-Xfatal-warnings").value


modules/macros/src/test/scala-3/higherkindness/droste/derivation/DerivedTests.scala

pepegar · 2021-07-19T10:07:50Z

project/ProjectPlugin.scala

+      Compile / unmanagedSourceDirectories ++= {
+        val sourceDir = (Compile / sourceDirectory).value
+        CrossVersion.partialVersion(scalaVersion.value) match {
+          case Some((3, _))  => Seq(sourceDir / "scala-2.13+")
+          case Some((2, 12)) => Seq()
+          case Some((2, _))  => Seq(sourceDir / "scala-2.13+")
+          case _             => Seq()
+        }
+      }


build.sbt

- This doesn't include derivation macros yet - I've tried to keep api changes to a minimum - The various `data` types `apply`/`un` methods in scala3 use `.isInstanceOf` directly - this might be slower than the scala2 `fastCast` macro

By shamelessly copying code from `kittens`

diesalbla · 2021-07-19T20:07:46Z

athema/src/main/scala/higherkindness/athema/expr.scala

+        case e: Neg[V, A]   => f(e.x) map (Neg(_))
+        case e: Add[V, A]   => (f(e.x), f(e.y)) mapN (Add(_, _))
+        case e: Sub[V, A]   => (f(e.x), f(e.y)) mapN (Sub(_, _))
+        case e: Prod[V, A]  => (f(e.x), f(e.y)) mapN (Prod(_, _))
+        case e: Div[V, A]   => (f(e.x), f(e.y)) mapN (Div(_, _))


As a BTW, are we still too keen on infix syntax?

Suggested change

case e: Neg[V, A] => f(e.x) map (Neg(_))

case e: Add[V, A] => (f(e.x), f(e.y)) mapN (Add(_, _))

case e: Sub[V, A] => (f(e.x), f(e.y)) mapN (Sub(_, _))

case e: Prod[V, A] => (f(e.x), f(e.y)) mapN (Prod(_, _))

case e: Div[V, A] => (f(e.x), f(e.y)) mapN (Div(_, _))

case e: Neg[V, A] => f(e.x) map (Neg(_))

case e: Add[V, A] => (f(e.x), f(e.y)).mapN(Add(_, _))

case e: Sub[V, A] => (f(e.x), f(e.y)).mapN(Sub(_, _))

case e: Prod[V, A] => (f(e.x), f(e.y)).mapN(Prod(_, _))

case e: Div[V, A] => (f(e.x), f(e.y)).mapN(Div(_, _))

specially if it saves no parentheses.

I'm personally not keen on it, I just left things as they were mainly and how scalafmt left them

diesalbla · 2021-07-19T20:09:46Z

athema/src/main/scala/higherkindness/athema/parser.scala

@@ -45,7 +45,7 @@ object ExprParser {
          case TSub      => shunt(op, 1).flatMap(_.traverse(enqueue))
          case TProd     => shunt(op, 2).flatMap(_.traverse(enqueue))
          case TDiv      => shunt(op, 2).flatMap(_.traverse(enqueue))
-        }).as(tail.asLeft)
+        }).map(_ => tail.asLeft)


I think it was proposed, at some point, as a replacement for the @ in pattern matching. I had some comments about that.

Daenyth force-pushed the gb-scala3 branch from b5be7ec to b5a5a8f Compare July 14, 2021 20:41

Daenyth requested review from pepegar and andyscott July 14, 2021 20:46

Daenyth marked this pull request as ready for review July 14, 2021 20:46

Daenyth commented Jul 14, 2021

View reviewed changes

Daenyth force-pushed the gb-scala3 branch from 6c46c70 to 2e2388f Compare July 15, 2021 11:56

pepegar previously approved these changes Jul 19, 2021

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pepegar reviewed Jul 19, 2021

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build.sbt Outdated Show resolved Hide resolved

Daenyth dismissed pepegar’s stale review via 0859fb5 July 19, 2021 13:24

Daenyth force-pushed the gb-scala3 branch from 6c377a3 to 0859fb5 Compare July 19, 2021 13:24

Crossbuild scala 3

833c4ee

- This doesn't include derivation macros yet - I've tried to keep api changes to a minimum - The various `data` types `apply`/`un` methods in scala3 use `.isInstanceOf` directly - this might be slower than the scala2 `fastCast` macro

Daenyth force-pushed the gb-scala3 branch from 0859fb5 to be54f41 Compare July 19, 2021 13:26

Add support for deriveTraverse in scala3

51fe47f

By shamelessly copying code from `kittens`

Daenyth force-pushed the gb-scala3 branch from be54f41 to 51fe47f Compare July 19, 2021 13:43

Daenyth requested a review from pepegar July 19, 2021 14:05

diesalbla approved these changes Jul 19, 2021

View reviewed changes

Daenyth merged commit ccbd2f6 into main Jul 20, 2021

Daenyth deleted the gb-scala3 branch July 20, 2021 12:17

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Crossbuild scala-3 #206

Crossbuild scala-3 #206

Daenyth commented Jul 14, 2021 •

edited

Daenyth Jul 14, 2021

Daenyth Jul 14, 2021

diesalbla Jul 19, 2021

Daenyth Jul 14, 2021

Daenyth Jul 14, 2021 •

edited

pepegar Jul 19, 2021

Daenyth Jul 14, 2021

Daenyth Jul 14, 2021

Daenyth Jul 14, 2021

Daenyth Jul 14, 2021

Daenyth Jul 14, 2021

Daenyth Jul 14, 2021

pepegar left a comment

pepegar Jul 19, 2021

pepegar Jul 19, 2021

diesalbla Jul 19, 2021

Daenyth Jul 19, 2021

diesalbla Jul 19, 2021

		// 'nowarn' doesn't work on scala3 yet, make warnings not fatal.
		scalacOptions --= on(3)("-Xfatal-warnings").value

		import higherkindness.droste.data.prelude._
		import higherkindness.droste.util.DefaultTraverse

		def apply[F[_], A](f: (A, F[Attr[F, A]])): Attr[F, A] = f.asInstanceOf
		def un[F[_], A](f: Attr[F, A]): (A, F[Attr[F, A]]) = f.asInstanceOf

Crossbuild scala-3 #206

Crossbuild scala-3 #206

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Daenyth commented Jul 14, 2021 •

edited

Daenyth Jul 14, 2021 •

edited