Merge pull request #5543 from dotty-staging/add-tasty-list-of-expr-ops

 Add `List[Expr[T]]` to `Expr[List[T]]` conversion in the library

Author: nicolasstucki

library/src-scala3/scala/quoted/package.scala

@@ -0,0 +1,18 @@
+package scala
+
+package object quoted {
+
+  implicit class LiftExprOps[T](val x: T) extends AnyVal {
+    def toExpr(implicit ev: Liftable[T]): Expr[T] = ev.toExpr(x)
+  }
+
+  implicit class ListOfExprOps[T](val list: List[Expr[T]]) extends AnyVal {
+    def toExprOfList(implicit ev: Type[T]): Expr[List[T]] = {
+      def rec(list: List[Expr[T]]): Expr[List[T]] = list match {
+        case x :: xs  => '{ (~x) :: (~rec(xs)) }
+        case Nil => '(Nil)
+      }
+      rec(list)
+    }
+  }
+}

library/src/scala/quoted/package.scala

@@ -56,11 +56,7 @@ object XmlQuote {
     // [a0, ...]: Any*
     val args2: Expr[List[Any]] = args.unseal.underlyingArgument match {
       case Typed(Repeated(args0), _) => // statically known args, make list directly
-        def liftListOfAny(lst: List[Expr[Any]]): Expr[List[Any]] = lst match {
-          case x :: xs  => '{ ~x :: ~liftListOfAny(xs) }
-          case Nil => '(Nil)
-        }
-        liftListOfAny(args0.map(_.seal[Any]))
+        args0.map(_.seal[Any]).toExprOfList
       case _ =>
         '((~args).toList)