Merge pull request #6618 from dotty-staging/improve-quoted-expr-FunctionBetaReduction

Use TupledFunction for Expr.FunctionBetaReduction

Author: nicolasstucki

compiler/src/dotty/tools/dotc/core/Definitions.scala

@@ -1260,7 +1260,7 @@ class Definitions {
   }
 
   def tupleTypes(tp: Type, bound: Int = Int.MaxValue)(implicit ctx: Context): Option[List[Type]] = {
-    @tailrec def rec(tp: Type, acc: List[Type], bound: Int): Option[List[Type]] = tp match {
+    @tailrec def rec(tp: Type, acc: List[Type], bound: Int): Option[List[Type]] = tp.normalized match {
       case _ if bound < 0 => Some(acc.reverse)
       case tp: AppliedType if defn.PairClass == tp.classSymbol => rec(tp.args(1), tp.args.head :: acc, bound - 1)
       case tp: AppliedType if defn.isTupleClass(tp.tycon.classSymbol) => Some(acc.reverse ::: tp.args)

compiler/src/dotty/tools/dotc/transform/TupleOptimizations.scala

@@ -36,7 +36,7 @@ class TupleOptimizations extends MiniPhase with IdentityDenotTransformer {
 
   private def transformTupleCons(tree: tpd.Apply)(implicit ctx: Context): Tree = {
     val head :: tail :: Nil = tree.args
-    tupleTypes(tree.tpe) match {
+    defn.tupleTypes(tree.tpe) match {
       case Some(tpes) =>
         // Generate a the tuple directly with TupleN+1.apply
         val size = tpes.size
@@ -64,7 +64,7 @@ class TupleOptimizations extends MiniPhase with IdentityDenotTransformer {
 
   private def transformTupleTail(tree: tpd.Apply)(implicit ctx: Context): Tree = {
     val Apply(TypeApply(_, tpt :: Nil), tup :: Nil) = tree
-    tupleTypes(tpt.tpe, MaxTupleArity + 1) match {
+    defn.tupleTypes(tpt.tpe, MaxTupleArity + 1) match {
       case Some(tpes) =>
         // Generate a the tuple directly with TupleN-1.apply
         val size = tpes.size
@@ -111,7 +111,7 @@ class TupleOptimizations extends MiniPhase with IdentityDenotTransformer {
   private def transformTupleConcat(tree: tpd.Apply)(implicit ctx: Context): Tree = {
     val Apply(TypeApply(_, selfTp :: thatTp :: Nil), self :: that :: Nil) = tree
 
-    (tupleTypes(selfTp.tpe), tupleTypes(that.tpe.widenTermRefExpr)) match {
+    (defn.tupleTypes(selfTp.tpe), defn.tupleTypes(that.tpe.widenTermRefExpr)) match {
       case (Some(tpes1), Some(tpes2)) =>
         // Generate a the tuple directly with TupleN+M.apply
         val n = tpes1.size
@@ -146,7 +146,7 @@ class TupleOptimizations extends MiniPhase with IdentityDenotTransformer {
 
   private def transformTupleApply(tree: tpd.Apply)(implicit ctx: Context): Tree = {
     val Apply(TypeApply(_, tpt :: nTpt :: Nil), tup :: nTree :: Nil) = tree
-    (tupleTypes(tpt.tpe), nTpt.tpe) match {
+    (defn.tupleTypes(tpt.tpe), nTpt.tpe) match {
       case (Some(tpes), nTpe: ConstantType) =>
         // Get the element directly with TupleM._n+1 or TupleXXL.productElement(n)
         val size = tpes.size
@@ -173,7 +173,7 @@ class TupleOptimizations extends MiniPhase with IdentityDenotTransformer {
 
   private def transformTupleToArray(tree: tpd.Apply)(implicit ctx: Context): Tree = {
     val Apply(_, tup :: Nil) = tree
-    tupleTypes(tup.tpe.widen, MaxTupleArity) match {
+    defn.tupleTypes(tup.tpe.widen, MaxTupleArity) match {
       case Some(tpes) =>
         val size = tpes.size
         if (size == 0) {
@@ -222,17 +222,6 @@ class TupleOptimizations extends MiniPhase with IdentityDenotTransformer {
     }
   }
 
-  private def tupleTypes(tp: Type, bound: Int = Int.MaxValue)(implicit ctx: Context): Option[List[Type]] = {
-    @tailrec def rec(tp: Type, acc: List[Type], bound: Int): Option[List[Type]] = tp match {
-      case _ if bound < 0 => Some(acc.reverse)
-      case tp: AppliedType if defn.PairClass == tp.classSymbol => rec(tp.args(1), tp.args.head :: acc, bound - 1)
-      case tp: AppliedType if defn.isTupleClass(tp.tycon.classSymbol) => Some(acc.reverse ::: tp.args)
-      case tp if tp.classSymbol == defn.UnitClass => Some(acc.reverse)
-      case _ => None
-    }
-    rec(tp.stripTypeVar, Nil, bound)
-  }
-
   private def tupleSelectors(tup: Tree, size: Int)(implicit ctx: Context): List[Tree] =
     (0 until size).map(i => tup.select(nme.selectorName(i))).toList
 

compiler/src/dotty/tools/dotc/typer/Implicits.scala

@@ -720,7 +720,7 @@ trait Implicits { self: Typer =>
             // TupledFunction[?, (...) => R]
             tupled.dropDependentRefinement.dealias.argInfos match {
               case tupledArgs :: funRet :: Nil =>
-                defn.tupleTypes(tupledArgs) match {
+                defn.tupleTypes(tupledArgs.dealias) match {
                   case Some(funArgs) if functionTypeEqual(tupled, funArgs, funRet, fun) =>
                     // TupledFunction[?, ((...funArgs...)) => funRet]
                     funArgs.size

docs/docs/reference/metaprogramming/macros.md

@@ -135,24 +135,24 @@ expressiveness.
 
 ### From `Expr`s to Functions and Back
 
-The `Expr` companion object contains an implicit `AsFunctionN` (for 0 <= N < 23) conversion that turns a tree
+The `Expr` companion object contains an implicit `AsFunction` conversion that turns a tree
 describing a function into a function mapping trees to trees.
 ```scala
     object Expr {
       ...
-      implied AsFunction1[T, U] for Conversion[Expr[T => U], Expr[T] => Expr[U]] ...
+      implicit class AsFunction[...](...) { ... }
     }
 ```
 This decorator gives `Expr` the `apply` operation of an applicative functor, where `Expr`s
 over function types can be applied to `Expr` arguments. The definition
-of `AsFunction1(f).apply(x)` is assumed to be functionally the same as
+of `AsFunction(f).apply(x)` is assumed to be functionally the same as
 `'{($f)($x)}`, however it should optimize this call by returning the
 result of beta-reducing `f(x)` if `f` is a known lambda expression.
 
-The `AsFunction1` decorator distributes applications of `Expr` over function
+The `AsFunction` decorator distributes applications of `Expr` over function
 arrows:
 ```scala
-    AsFunction1(_).apply: Expr[S => T] => (Expr[S] => Expr[T])
+    AsFunction(_).apply: Expr[S => T] => (Expr[S] => Expr[T])
 ```
 Its dual, let’s call it `reflect`, can be defined as follows:
 ```scala

library/src-3.x/scala/Tuple.scala

@@ -64,6 +64,12 @@ object Tuple {
     case x *: xs => S[Size[xs]]
   }
 
+  /** Converts a tuple `(T1, ..., Tn)` to `(F[T1], ..., F[Tn])` */
+  type Map[Tup <: Tuple, F[_]] <: Tuple = Tup match {
+    case Unit => Unit
+    case h *: t => F[h] *: Map[t, F]
+  }
+
   /** Convert an array into a tuple of unknown arity and types */
   def fromArray[T](xs: Array[T]): Tuple = {
     val xs2 = xs match {