Add quoted.{Lifted,Unlifted}

As a dual of lifting (Expr.apply), unliftings should be placed consistent namespaces.

* Move `Values.unapply to `Unlifted.unapply`
* Move `Value.unapply` to `Unlifted.unapply(Seq)`
* Move `Expr.unapply` to `Lifted.unapply`

Author: nicolasstucki

docs/docs/reference/changed-features/numeric-literals.md

@@ -206,7 +206,7 @@ implementation method `fromDigitsImpl`. Here is its definition:
       case Const(ds) =>
         try {
           val BigFloat(m, e) = apply(ds)
-          '{BigFloat(${Expr(m)}, ${Expr(e)})}
+          '{BigFloat(${Lifted(m)}, ${Lifted(e)})}
         }
         catch {
           case ex: FromDigits.FromDigitsException =>

docs/docs/reference/contextual/derivation-macro.md

@@ -50,10 +50,10 @@ given derived[T: Type](using qctx: QuoteContext) as Expr[Eq[T]] = {
     case '{ $m: Mirror.ProductOf[T] { type MirroredElemTypes = $elementTypes }} =>
       val elemInstances = summonAll(elementTypes)
       val eqProductBody: (Expr[T], Expr[T]) => Expr[Boolean] = (x, y) => {
-        elemInstances.zipWithIndex.foldLeft(Expr(true: Boolean)) {
+        elemInstances.zipWithIndex.foldLeft(Lifted(true: Boolean)) {
           case (acc, (elem, index)) =>
-            val e1 = '{$x.asInstanceOf[Product].productElement(${Expr(index)})}
-            val e2 = '{$y.asInstanceOf[Product].productElement(${Expr(index)})}
+            val e1 = '{$x.asInstanceOf[Product].productElement(${Lifted(index)})}
+            val e2 = '{$y.asInstanceOf[Product].productElement(${Lifted(index)})}
 
             '{ $acc && $elem.asInstanceOf[Eq[Any]].eqv($e1, $e2) }
         }
@@ -184,10 +184,10 @@ object Eq {
       case '{ $m: Mirror.ProductOf[T] { type MirroredElemTypes = $elementTypes }} =>
         val elemInstances = summonAll(elementTypes)
         val eqProductBody: (Expr[T], Expr[T]) => Expr[Boolean] = (x, y) => {
-          elemInstances.zipWithIndex.foldLeft(Expr(true: Boolean)) {
+          elemInstances.zipWithIndex.foldLeft(Lifted(true: Boolean)) {
             case (acc, (elem, index)) =>
-              val e1 = '{$x.asInstanceOf[Product].productElement(${Expr(index)})}
-              val e2 = '{$y.asInstanceOf[Product].productElement(${Expr(index)})}
+              val e1 = '{$x.asInstanceOf[Product].productElement(${Lifted(index)})}
+              val e2 = '{$y.asInstanceOf[Product].productElement(${Lifted(index)})}
 
               '{ $acc && $elem.asInstanceOf[Eq[Any]].eqv($e1, $e2) }
           }

docs/docs/reference/metaprogramming/macros.md

@@ -225,7 +225,7 @@ import scala.quoted.{given _, _}
 
 def compile(e: Exp, env: Map[String, Expr[Int]])(using QuoteContext): Expr[Int] = e match {
   case Num(n) =>
-    Expr(n)
+    Lifted(n)
   case Plus(e1, e2) =>
     '{ ${ compile(e1, env) } + ${ compile(e2, env) } }
   case Var(x) =>
@@ -238,19 +238,19 @@ Running `compile(letExp, Map())` would yield the following Scala code:
 ```scala
 '{ val y = 3; (2 + y) + 4 }
 ```
-The body of the first clause, `case Num(n) => Expr(n)`, looks suspicious. `n`
-is declared as an `Int`, yet it is converted to an `Expr[Int]` with `Expr()`.
+The body of the first clause, `case Num(n) => Lifted(n)`, looks suspicious. `n`
+is declared as an `Int`, yet it is converted to an `Expr[Int]` with `Lifted()`.
 Shouldn’t `n` be quoted? In fact this would not
 work since replacing `n` by `'n` in the clause would not be phase
 correct.
 
-The `Expr.apply` method is defined in package `quoted`:
+The `Lifted.apply` method is defined in package `quoted`:
 ```scala
 package quoted
 
-object Expr {
+object Lifted {
   ...
-  def apply[T: Liftable](x: T)(using QuoteContext): Expr[T] = summon[Liftable[T]].toExpr(x)
+  def apply[T](x: T)(using qctx: QuoteContext, lift: Liftable[T]): Expr[T] = lift.toExpr(x)
   ...
 }
 ```
@@ -291,7 +291,7 @@ a `List` is liftable if its element type is:
 ```scala
 given [T: Liftable : Type] as Liftable[List[T]] {
   def toExpr(xs: List[T]) = xs match {
-    case head :: tail => '{ ${ Expr(head) } :: ${ toExpr(tail) } }
+    case head :: tail => '{ ${ Lifted(head) } :: ${ toExpr(tail) } }
     case Nil => '{ Nil: List[T] }
   }
 }
@@ -306,13 +306,13 @@ Using lifting, we can now give the missing definition of `showExpr` in the intro
 ```scala
 def showExpr[T](expr: Expr[T])(using QuoteContext): Expr[String] = {
   val code: String = expr.show
-  Expr(code)
+  Lifted(code)
 }
 ```
 That is, the `showExpr` method converts its `Expr` argument to a string (`code`), and lifts
-the result back to an `Expr[String]` using `Expr.apply`.
+the result back to an `Expr[String]` using `Lifted.apply`.
 
-**Note**: Lifting `String` to `Expr[String]` using `Expr(code)` can be omitted by importing an implicit
+**Note**: Lifting `String` to `Expr[String]` using `Lifted(code)` can be omitted by importing an implicit
 conversion with `import scala.quoted.autolift.given`. The programmer is able to
 declutter slightly the code at the cost of readable _phase distinction_ between
 stages.
@@ -617,15 +617,15 @@ It is possible to deconstruct or extract values out of `Expr` using pattern matc
 `scala.quoted` contains objects that can help extracting values from `Expr`.
 
 * `scala.quoted.Const`/`scala.quoted.Consts`: matches an expression of a literal value (or list of values) and returns the value (or list of values).
-* `scala.quoted.Value`/`scala.quoted.Values`: matches an expression of a value (or list of values) and returns the value (or list of values).
+* `scala.quoted.Unlifted`: matches an expression of a value (or list of values) and returns the value (or list of values).
 * `scala.quoted.Varargs`: matches an explicit sequence of expresions and returns them. These sequences are useful to get individual `Expr[T]` out of a varargs expression of type `Expr[Seq[T]]`.
 
 These could be used in the following way to optimize any call to `sum` that has statically known values.
 ```scala
 inline def sum(inline args: Int*): Int = ${ sumExpr('args) }
 private def sumExpr(argsExpr: Expr[Seq[Int]])(using QuoteContext): Expr[Int] = argsExpr match {
   case Varargs(Consts(args)) => // args is of type Seq[Int]
-    Expr(args.sum) // precompute result of sum
+    Lifted(args.sum) // precompute result of sum
   case Varargs(argExprs) => // argExprs is of type Seq[Expr[Int]]
     val staticSum: Int = argExprs.map {
       case Const(arg) => arg
@@ -635,7 +635,7 @@ private def sumExpr(argsExpr: Expr[Seq[Int]])(using QuoteContext): Expr[Int] = a
       case Const(_) => false
       case arg => true
     }
-    dynamicSum.foldLeft(Expr(staticSum))((acc, arg) => '{ $acc + $arg })
+    dynamicSum.foldLeft(Lifted(staticSum))((acc, arg) => '{ $acc + $arg })
   case _ =>
     '{ $argsExpr.sum }
 }
@@ -658,7 +658,7 @@ def sum(args: Int*): Int = args.sum
 inline def optimize(arg: Int): Int = ${ optimizeExpr('arg) }
 private def optimizeExpr(body: Expr[Int])(using QuoteContext): Expr[Int] = body match {
   // Match a call to sum without any arguments
-  case '{ sum() } => Expr(0)
+  case '{ sum() } => Lifted(0)
   // Match a call to sum with an argument $n of type Int. n will be the Expr[Int] representing the argument.
   case '{ sum($n) } => n
   // Match a call to sum and extracts all its args in an `Expr[Seq[Int]]`
@@ -679,7 +679,7 @@ private def sumExpr(args1: Seq[Expr[Int]])(using QuoteContext): Expr[Int] = {
       case Const(_) => false
       case arg => true
     }
-    dynamicSum.foldLeft(Expr(staticSum))((acc, arg) => '{ $acc + $arg })
+    dynamicSum.foldLeft(Lifted(staticSum))((acc, arg) => '{ $acc + $arg })
 }
 ```
 

docs/docs/reference/metaprogramming/tasty-reflect.md

@@ -65,7 +65,7 @@ The method `qctx.tasty.Term.seal` provides a way to go back to a
 `quoted.Expr[Any]`. Note that the type is `Expr[Any]`. Consequently, the type
 must be set explicitly with a checked `cast` call. If the type does not conform
 to it an exception will be thrown. In the code above, we could have replaced
-`Expr(n)` by `xTree.seal.cast[Int]`.
+`Lifted(n)` by `xTree.seal.cast[Int]`.
 
 ### Obtaining the underlying argument
 

library/src-bootstrapped/dotty/internal/StringContextMacro.scala

@@ -721,6 +721,6 @@ object StringContextMacro {
     }
 
     // macro expansion
-    '{(${Expr(parts.mkString)}).format(${argsExpr}: _*)}
+    '{(${Lifted(parts.mkString)}).format(${argsExpr}: _*)}
   }
 }

library/src/scala/internal/quoted/showName.scala

@@ -6,7 +6,7 @@ package scala.internal.quoted
  *  Usage:
  *  ```scala
  *  def let(name: String)(value: Expr[Int])(in: Expr[Int] => Expr[Int]): Expr[Int] = '{
- *    @showName(${Expr(name)})
+ *    @showName(${Lifted(name)})
  *    val x = $value
  *    ${ in('x) }
  *  }

library/src/scala/quoted/Expr.scala

@@ -97,8 +97,9 @@ object Expr {
     Block(statements.map(_.unseal), expr.unseal).seal.asInstanceOf[Expr[T]]
   }
 
-  /** Lift a value into an expression containing the construction of that value */
-  def apply[T](x: T)(using qctx: QuoteContext, lift: Liftable[T]): Expr[T] = lift.toExpr(x)
+  // /** Lift a value into an expression containing the construction of that value */
+  // @deprecated("Use scala.quoted.Lifted", "0.23")
+  // def apply[T](x: T)(using qctx: QuoteContext, lift: Liftable[T]): Expr[T] = Lifted(x)
 
   /** Lifts this sequence of expressions into an expression of a sequence
    *