Add defn.FunctionNOf

Author: nicolasstucki

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

@@ -1109,23 +1109,47 @@ class Definitions {
     sym.owner.linkedClass.typeRef
 
   object FunctionOf {
+    /** Create a `FunctionN`, `ContextFunctionN` or refined `PolyFunction` type applied to the arguments and result type
+     *
+     *  `PolyFunction` is used if at least one of the arguments is annotated as erased.
+     */
     def apply(args: List[Type], resultType: Type, isContextual: Boolean = false)(using Context): Type =
       val mt = MethodType.companion(isContextual, false)(args, resultType)
       if mt.hasErasedParams then
         RefinedType(PolyFunctionClass.typeRef, nme.apply, mt)
       else
-        FunctionType(args.length, isContextual).appliedTo(args ::: resultType :: Nil)
+        FunctionNOf(args, resultType, isContextual)
+
+    /** Matches a (possibly aliased) `FunctionN[...]`, `ContextFunctionN[...]` or refined `PolyFunction`.
+     *  Extracts the list of function argument types, the result type and whether function is contextual.
+     */
     def unapply(ft: Type)(using Context): Option[(List[Type], Type, Boolean)] = {
       ft.dealias match
         case PolyFunctionOf(mt: MethodType) =>
           Some(mt.paramInfos, mt.resType, mt.isContextualMethod)
-        case dft =>
-          val tsym = dft.typeSymbol
-          if isFunctionSymbol(tsym) && ft.isRef(tsym) then
-            val targs = dft.argInfos
-            if (targs.isEmpty) None
-            else Some(targs.init, targs.last, tsym.name.isContextFunction)
-          else None
+        case FunctionNOf(targs, resType, isContextual) =>
+          Some(targs, resType, isContextual)
+        case _ =>
+          None
+    }
+  }
+
+  object FunctionNOf {
+    /** Create a `FunctionN` or `ContextFunctionN` type applied to the arguments and result type */
+    def apply(args: List[Type], resultType: Type, isContextual: Boolean = false)(using Context): Type =
+      FunctionType(args.length, isContextual).appliedTo(args ::: resultType :: Nil)
+
+    /** Matches a (possibly aliased) `FunctionN[...]` or `ContextFunctionN[...]`.
+     *  Extracts the list of function argument types, the result type and whether function is contextual.
+     */
+    def unapply(ft: Type)(using Context): Option[(List[Type], Type, Boolean)] = {
+      val dft = ft.dealias
+      val tsym = dft.typeSymbol
+      if isFunctionSymbol(tsym) && ft.isRef(tsym) then
+        val targs = dft.argInfos
+        if (targs.isEmpty) None
+        else Some(targs.init, targs.last, tsym.name.isContextFunction)
+      else None
     }
   }
 

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

@@ -933,7 +933,7 @@ class TypeErasure(sourceLanguage: SourceLanguage, semiEraseVCs: Boolean, isConst
       case tp: TermRef =>
         sigName(underlyingOfTermRef(tp))
       case ExprType(rt) =>
-        sigName(defn.FunctionOf(Nil, rt))
+        sigName(defn.FunctionNOf(Nil, rt))
       case tp: TypeVar if !tp.isInstantiated =>
         tpnme.Uninstantiated
       case tp @ defn.PolyFunctionOf(_) =>

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

@@ -1882,7 +1882,7 @@ object Types {
             case res: MethodType => res.toFunctionType(isJava)
             case res => res
           }
-          defn.FunctionOf(
+          defn.FunctionNOf(
             formals1 mapConserve (_.translateFromRepeated(toArray = isJava)),
             result1, isContextual)
         if mt.hasErasedParams then

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

@@ -326,7 +326,7 @@ object PickleQuotes {
               defn.QuotedExprClass.typeRef.appliedTo(defn.AnyType)),
             args =>
               val cases = holeContents.zipWithIndex.map { case (splice, idx) =>
-                val defn.FunctionOf(argTypes, defn.FunctionOf(quotesType :: _, _, _), _) = splice.tpe: @unchecked
+                val defn.FunctionNOf(argTypes, defn.FunctionNOf(quotesType :: _, _, _), _) = splice.tpe: @unchecked
                 val rhs = {
                   val spliceArgs = argTypes.zipWithIndex.map { (argType, i) =>
                     args(1).select(nme.apply).appliedTo(Literal(Constant(i))).asInstance(argType)

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

@@ -88,7 +88,7 @@ class SpecializeFunctions extends MiniPhase {
                   // Need to cast to regular function, since specialized apply methods
                   // are not members of ContextFunction0. The cast will be eliminated in
                   // erasure.
-                  qual.cast(defn.FunctionOf(Nil, res))
+                  qual.cast(defn.FunctionNOf(Nil, res))
                 case _ =>
                   qual
               qual1.select(specializedApply)

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

@@ -749,9 +749,9 @@ object TreeChecker {
         if isTerm then defn.QuotedExprClass.typeRef.appliedTo(tree1.typeOpt)
         else defn.QuotedTypeClass.typeRef.appliedTo(tree1.typeOpt)
       val contextualResult =
-        defn.FunctionOf(List(defn.QuotesClass.typeRef), expectedResultType, isContextual = true)
+        defn.FunctionNOf(List(defn.QuotesClass.typeRef), expectedResultType, isContextual = true)
       val expectedContentType =
-        defn.FunctionOf(argQuotedTypes, contextualResult)
+        defn.FunctionNOf(argQuotedTypes, contextualResult)
       assert(content.typeOpt =:= expectedContentType, i"unexpected content of hole\nexpected: ${expectedContentType}\nwas: ${content.typeOpt}")
 
       tree1

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

@@ -1934,7 +1934,7 @@ trait Applications extends Compatibility {
     /** The shape of given tree as a type; cannot handle named arguments. */
     def typeShape(tree: untpd.Tree): Type = tree match {
       case untpd.Function(args, body) =>
-        defn.FunctionOf(
+        defn.FunctionNOf(
           args.map(Function.const(defn.AnyType)), typeShape(body),
           isContextual = untpd.isContextualClosure(tree))
       case Match(EmptyTree, _) =>

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

@@ -122,7 +122,7 @@ trait QuotesAndSplices {
       for arg <- typedArgs if arg.symbol.is(Mutable) do // TODO support these patterns. Possibly using scala.quoted.util.Var
         report.error("References to `var`s cannot be used in higher-order pattern", arg.srcPos)
       val argTypes = typedArgs.map(_.tpe.widenTermRefExpr)
-      val patType = if tree.args.isEmpty then pt else defn.FunctionOf(argTypes, pt)
+      val patType = if tree.args.isEmpty then pt else defn.FunctionNOf(argTypes, pt)
       val pat = typedPattern(tree.body, defn.QuotedExprClass.typeRef.appliedTo(patType))(using quotePatternSpliceContext)
       val baseType = pat.tpe.baseType(defn.QuotedExprClass)
       val argType = if baseType.exists then baseType.argTypesHi.head else defn.NothingType
@@ -148,7 +148,7 @@ trait QuotesAndSplices {
     if isInBraces then // ${x}(...) match an application
       val typedArgs = args.map(arg => typedExpr(arg))
       val argTypes = typedArgs.map(_.tpe.widenTermRefExpr)
-      val splice1 = typedSplicePattern(splice, defn.FunctionOf(argTypes, pt))
+      val splice1 = typedSplicePattern(splice, defn.FunctionNOf(argTypes, pt))
       untpd.cpy.Apply(tree)(splice1.select(nme.apply), typedArgs).withType(pt)
     else // $x(...) higher-order quasipattern
       if args.isEmpty then

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

@@ -102,7 +102,7 @@ class Synthesizer(typer: Typer)(using @constructorOnly c: Context):
       case AppliedType(_, funArgs @ fun :: tupled :: Nil) =>
         def functionTypeEqual(baseFun: Type, actualArgs: List[Type],
             actualRet: Type, expected: Type) =
-          expected =:= defn.FunctionOf(actualArgs, actualRet,
+          expected =:= defn.FunctionNOf(actualArgs, actualRet,
             defn.isContextFunctionType(baseFun))
         val arity: Int =
           if defn.isFunctionNType(fun) then