Implement suspension of default arguments (#170)

Interpreter/src/main/java/org/enso/interpreter/builder/CallArgFactory.java

@@ -12,6 +12,7 @@ import org.enso.interpreter.runtime.scope.LocalScope;
  * runtime nodes used by the interpreter to guide function evaluation.
  */
 public class CallArgFactory implements AstCallArgVisitor<CallArgument> {
+
   private final LocalScope scope;
   private final Language language;
   private final String scopeName;

Interpreter/src/main/java/org/enso/interpreter/builder/ExpressionFactory.java

@@ -4,19 +4,42 @@ import com.oracle.truffle.api.RootCallTarget;
 import com.oracle.truffle.api.Truffle;
 import com.oracle.truffle.api.frame.FrameSlot;
 import com.oracle.truffle.api.nodes.RootNode;
-import org.enso.interpreter.*;
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Optional;
+import java.util.Set;
+import java.util.function.Supplier;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+import org.enso.interpreter.AstArgDefinition;
+import org.enso.interpreter.AstCallArg;
+import org.enso.interpreter.AstCase;
+import org.enso.interpreter.AstCaseFunction;
+import org.enso.interpreter.AstExpression;
+import org.enso.interpreter.AstExpressionVisitor;
+import org.enso.interpreter.Language;
 import org.enso.interpreter.node.EnsoRootNode;
 import org.enso.interpreter.node.ExpressionNode;
 import org.enso.interpreter.node.callable.InvokeCallableNodeGen;
 import org.enso.interpreter.node.callable.argument.ReadArgumentNode;
 import org.enso.interpreter.node.callable.function.CreateFunctionNode;
 import org.enso.interpreter.node.callable.function.FunctionBodyNode;
-import org.enso.interpreter.node.controlflow.*;
+import org.enso.interpreter.node.controlflow.CaseNode;
+import org.enso.interpreter.node.controlflow.ConstructorCaseNode;
+import org.enso.interpreter.node.controlflow.DefaultFallbackNode;
+import org.enso.interpreter.node.controlflow.FallbackNode;
+import org.enso.interpreter.node.controlflow.IfZeroNode;
+import org.enso.interpreter.node.controlflow.MatchNode;
 import org.enso.interpreter.node.expression.builtin.PrintNode;
 import org.enso.interpreter.node.expression.constant.ConstructorNode;
 import org.enso.interpreter.node.expression.constant.DynamicSymbolNode;
 import org.enso.interpreter.node.expression.literal.IntegerLiteralNode;
-import org.enso.interpreter.node.expression.operator.*;
+import org.enso.interpreter.node.expression.operator.AddOperatorNodeGen;
+import org.enso.interpreter.node.expression.operator.DivideOperatorNodeGen;
+import org.enso.interpreter.node.expression.operator.ModOperatorNodeGen;
+import org.enso.interpreter.node.expression.operator.MultiplyOperatorNodeGen;
+import org.enso.interpreter.node.expression.operator.SubtractOperatorNodeGen;
 import org.enso.interpreter.node.scope.AssignmentNode;
 import org.enso.interpreter.node.scope.AssignmentNodeGen;
 import org.enso.interpreter.node.scope.ReadLocalTargetNodeGen;
@@ -27,16 +50,12 @@ import org.enso.interpreter.runtime.error.DuplicateArgumentNameException;
 import org.enso.interpreter.runtime.scope.ModuleScope;
 import org.enso.interpreter.runtime.scope.LocalScope;
 
-import java.util.*;
-import java.util.function.Supplier;
-import java.util.stream.Collectors;
-import java.util.stream.Stream;
-
 /**
  * An {@code ExpressionFactory} is responsible for converting the majority of Enso's parsed AST into
  * nodes evaluated by the interpreter at runtime.
  */
 public class ExpressionFactory implements AstExpressionVisitor<ExpressionNode> {
+
   private final LocalScope scope;
   private final Language language;
   private final String scopeName;
@@ -128,11 +147,21 @@ public class ExpressionFactory implements AstExpressionVisitor<ExpressionNode> {
       String operator, AstExpression leftAst, AstExpression rightAst) {
     ExpressionNode left = leftAst.visit(this);
     ExpressionNode right = rightAst.visit(this);
-    if (operator.equals("+")) return AddOperatorNodeGen.create(left, right);
+    if (operator.equals("+")) {
-    if (operator.equals("-")) return SubtractOperatorNodeGen.create(left, right);
+      return AddOperatorNodeGen.create(left, right);
-    if (operator.equals("*")) return MultiplyOperatorNodeGen.create(left, right);
+    }
-    if (operator.equals("/")) return DivideOperatorNodeGen.create(left, right);
+    if (operator.equals("-")) {
-    if (operator.equals("%")) return ModOperatorNodeGen.create(left, right);
+      return SubtractOperatorNodeGen.create(left, right);
+    }
+    if (operator.equals("*")) {
+      return MultiplyOperatorNodeGen.create(left, right);
+    }
+    if (operator.equals("/")) {
+      return DivideOperatorNodeGen.create(left, right);
+    }
+    if (operator.equals("%")) {
+      return ModOperatorNodeGen.create(left, right);
+    }
     return null;
   }
 
@@ -300,7 +329,7 @@ public class ExpressionFactory implements AstExpressionVisitor<ExpressionNode> {
    */
   @Override
   public ExpressionNode visitFunctionApplication(
-      AstExpression function, List<AstCallArg> arguments) {
+      AstExpression function, List<AstCallArg> arguments, boolean hasDefaultsSuspended) {
     CallArgFactory argFactory = new CallArgFactory(scope, language, scopeName, moduleScope);
 
     List<CallArgument> callArgs = new ArrayList<>();
@@ -310,7 +339,7 @@ public class ExpressionFactory implements AstExpressionVisitor<ExpressionNode> {
     }
 
     return InvokeCallableNodeGen.create(
-        callArgs.stream().toArray(CallArgument[]::new), function.visit(this));
+        callArgs.toArray(new CallArgument[0]), hasDefaultsSuspended, function.visit(this));
   }
 
   /**

Interpreter/src/main/java/org/enso/interpreter/node/callable/InvokeCallableNode.java

@@ -8,6 +8,7 @@ import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.nodes.ExplodeLoop;
 import com.oracle.truffle.api.nodes.NodeInfo;
 import com.oracle.truffle.api.profiles.ConditionProfile;
+import java.util.Arrays;
 import org.enso.interpreter.Constants;
 import org.enso.interpreter.node.ExpressionNode;
 import org.enso.interpreter.node.callable.argument.sorter.ArgumentSorterNode;
@@ -22,8 +23,6 @@ import org.enso.interpreter.runtime.error.MethodDoesNotExistException;
 import org.enso.interpreter.runtime.error.NotInvokableException;
 import org.enso.interpreter.runtime.type.TypesGen;
 
-import java.util.Arrays;
-
 /**
  * This node is responsible for organising callable calls so that they are ready to be made.
  *
@@ -33,15 +32,17 @@ import java.util.Arrays;
 @NodeInfo(shortName = "@", description = "Executes function")
 @NodeChild(value = "callable", type = ExpressionNode.class)
 public abstract class InvokeCallableNode extends ExpressionNode {
-  @Children
-  private @CompilationFinal(dimensions = 1) ExpressionNode[] argExpressions;
 
-  private final boolean canApplyThis;
+  @Children
-  private final int thisArgumentPosition;
+  @CompilationFinal(dimensions = 1)
+  private ExpressionNode[] argExpressions;
 
   @Child private ArgumentSorterNode argumentSorter;
   @Child private MethodResolverNode methodResolverNode;
 
+  private final boolean canApplyThis;
+  private final int thisArgumentPosition;
+
   private final ConditionProfile methodCalledOnNonAtom = ConditionProfile.createCountingProfile();
 
   /**
@@ -49,7 +50,7 @@ public abstract class InvokeCallableNode extends ExpressionNode {
    *
    * @param callArguments information on the arguments being passed to the {@link Function}
    */
-  public InvokeCallableNode(CallArgument[] callArguments) {
+  public InvokeCallableNode(CallArgument[] callArguments, boolean hasDefaultsSuspended) {
     this.argExpressions =
         Arrays.stream(callArguments)
             .map(CallArgument::getExpression)
@@ -57,9 +58,9 @@ public abstract class InvokeCallableNode extends ExpressionNode {
 
     CallArgumentInfo[] argSchema =
         Arrays.stream(callArguments).map(CallArgumentInfo::new).toArray(CallArgumentInfo[]::new);
-
     boolean appliesThis = false;
     int idx = 0;
+
     for (; idx < argSchema.length; idx++) {
       CallArgumentInfo arg = argSchema[idx];
       if (arg.isPositional()
@@ -68,15 +69,17 @@ public abstract class InvokeCallableNode extends ExpressionNode {
         break;
       }
     }
+
     this.canApplyThis = appliesThis;
     this.thisArgumentPosition = idx;
 
-    this.argumentSorter = ArgumentSorterNodeGen.create(argSchema);
+    this.argumentSorter = ArgumentSorterNodeGen.create(argSchema, hasDefaultsSuspended);
     this.methodResolverNode = MethodResolverNodeGen.create();
   }
 
   /**
    * Marks whether the {@code argumentSorter} child is tail–recursive.
+   *
    * @param isTail whether or not the node is tail-recursive.
    */
   @Override

Interpreter/src/main/java/org/enso/interpreter/node/callable/argument/sorter/ArgumentSorterNode.java

@@ -16,18 +16,20 @@ import org.enso.interpreter.runtime.callable.function.Function;
  */
 @NodeInfo(shortName = "ArgumentSorter")
 public abstract class ArgumentSorterNode extends BaseNode {
+
   private @CompilationFinal(dimensions = 1) CallArgumentInfo[] schema;
+  private final boolean hasDefaultsSuspended;
 
   /**
    * Creates a node that performs the argument organisation for the provided schema.
    *
    * @param schema information about the call arguments in positional order
    */
-  public ArgumentSorterNode(CallArgumentInfo[] schema) {
+  public ArgumentSorterNode(CallArgumentInfo[] schema, boolean hasDefaultsSuspended) {
     this.schema = schema;
+    this.hasDefaultsSuspended = hasDefaultsSuspended;
   }
 
-
   /**
    * Generates the argument mapping where it has already been computed and executes the function.
    *
@@ -49,7 +51,8 @@ public abstract class ArgumentSorterNode extends BaseNode {
   public Object invokeCached(
       Function function,
       Object[] arguments,
-      @Cached("create(function, getSchema())") CachedArgumentSorterNode mappingNode,
+      @Cached("create(function, getSchema(), hasDefaultsSuspended())")
+          CachedArgumentSorterNode mappingNode,
       @Cached CallOptimiserNode optimiser) {
     Object[] mappedArguments = mappingNode.execute(function, arguments);
     if (mappingNode.appliesFully()) {
@@ -84,4 +87,13 @@ public abstract class ArgumentSorterNode extends BaseNode {
   CallArgumentInfo[] getSchema() {
     return schema;
   }
+
+  /**
+   * Checks whether the function whose arguments are being sorted has suspended defaults arguments.
+   *
+   * @return {@code true} if it has suspended defaults, otherwise {@code false}
+   */
+  boolean hasDefaultsSuspended() {
+    return this.hasDefaultsSuspended;
+  }
 }

Interpreter/src/main/java/org/enso/interpreter/node/callable/argument/sorter/CachedArgumentSorterNode.java

@@ -13,6 +13,7 @@ import org.enso.interpreter.runtime.callable.function.Function;
  */
 @NodeInfo(shortName = "CachedArgumentSorter")
 public class CachedArgumentSorterNode extends BaseNode {
+
   private final Function originalFunction;
   private final @CompilationFinal(dimensions = 1) int[] mapping;
   private final ArgumentSchema postApplicationSchema;
@@ -22,9 +23,12 @@ public class CachedArgumentSorterNode extends BaseNode {
    * Creates a node that generates and then caches the argument mapping.
    *
    * @param function the function to sort arguments for
-   * @param schema information on the calling arguments
+   * @param schema information on the calling argument
+   * @param hasDefaultsSuspended whether or not the function to which these arguments are applied
+   *     has its defaults suspended.
    */
-  public CachedArgumentSorterNode(Function function, CallArgumentInfo[] schema) {
+  public CachedArgumentSorterNode(
+      Function function, CallArgumentInfo[] schema, boolean hasDefaultsSuspended) {
     this.originalFunction = function;
     CallArgumentInfo.ArgumentMapping mapping =
         CallArgumentInfo.ArgumentMapping.generate(function.getSchema(), schema);
@@ -33,7 +37,10 @@ public class CachedArgumentSorterNode extends BaseNode {
 
     boolean fullApplication = true;
     for (int i = 0; i < postApplicationSchema.getArgumentsCount(); i++) {
-      if (!(postApplicationSchema.hasDefaultAt(i) || postApplicationSchema.hasPreAppliedAt(i))) {
+      boolean hasValidDefault = postApplicationSchema.hasDefaultAt(i) && !hasDefaultsSuspended;
+      boolean hasPreappliedArg = postApplicationSchema.hasPreAppliedAt(i);
+
+      if (!(hasValidDefault || hasPreappliedArg)) {
         fullApplication = false;
         break;
       }
@@ -48,8 +55,9 @@ public class CachedArgumentSorterNode extends BaseNode {
    * @param schema information on the calling arguments
    * @return a sorter node for the arguments in {@code schema} being passed to {@code callable}
    */
-  public static CachedArgumentSorterNode create(Function function, CallArgumentInfo[] schema) {
+  public static CachedArgumentSorterNode create(
-    return new CachedArgumentSorterNode(function, schema);
+      Function function, CallArgumentInfo[] schema, boolean hasDefaultsSuspended) {
+    return new CachedArgumentSorterNode(function, schema, hasDefaultsSuspended);
   }
 
   /**

Interpreter/src/main/java/org/enso/interpreter/runtime/Context.java

@@ -7,6 +7,12 @@ import com.oracle.truffle.api.TruffleLanguage;
 import com.oracle.truffle.api.TruffleLanguage.Env;
 import com.oracle.truffle.api.frame.FrameDescriptor;
 import com.oracle.truffle.api.source.Source;
+import java.io.File;
+import java.io.IOException;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.stream.Collectors;
 import org.enso.interpreter.AstGlobalScope;
 import org.enso.interpreter.Constants;
 import org.enso.interpreter.EnsoParser;
@@ -20,12 +26,6 @@ import org.enso.interpreter.util.ScalaConversions;
 import org.enso.pkg.Package;
 import org.enso.pkg.SourceFile;
 
-import java.io.*;
-import java.util.List;
-import java.util.Map;
-import java.util.Optional;
-import java.util.stream.Collectors;
-
 /**
  * The language context is the internal state of the language that is associated with each thread in
  * a running Enso program.

Interpreter/src/main/scala/org/enso/interpreter/Parser.scala

@@ -28,7 +28,8 @@ trait AstExpressionVisitor[+T] {
 
   def visitFunctionApplication(
     function: AstExpression,
-    arguments: java.util.List[AstCallArg]
+    arguments: java.util.List[AstCallArg],
+    defaultsSuspended: Boolean
   ): T
 
   def visitIf(
@@ -156,10 +157,13 @@ case class AstVariable(name: String) extends AstExpression {
     visitor.visitVariable(name)
 }
 
-case class AstApply(fun: AstExpression, args: List[AstCallArg])
+case class AstApply(
+  fun: AstExpression,
+  args: List[AstCallArg],
+  hasDefaultsSuspended: Boolean)
     extends AstExpression {
   override def visit[T](visitor: AstExpressionVisitor[T]): T =
-    visitor.visitFunctionApplication(fun, args.asJava)
+    visitor.visitFunctionApplication(fun, args.asJava, hasDefaultsSuspended)
 }
 
 case class AstFunction(
@@ -269,7 +273,7 @@ class EnsoParserInternal extends JavaTokenParsers {
   def variable: Parser[AstVariable] = ident ^^ AstVariable
 
   def operand: Parser[AstExpression] =
-    long | foreign | variable | "(" ~> expression <~ ")" | call
+    long | foreign | variable | "(" ~> expression <~ ")" | functionCall
 
   def arith: Parser[AstExpression] =
     operand ~ ((("+" | "-" | "*" | "/" | "%") ~ operand) ?) ^^ {
@@ -280,9 +284,17 @@ class EnsoParserInternal extends JavaTokenParsers {
   def expression: Parser[AstExpression] =
     ifZero | matchClause | arith | function
 
-  def call: Parser[AstApply] = "@" ~> expression ~ (argList ?) ^^ {
+  def functionCall: Parser[AstApply] =
-    case expr ~ args => AstApply(expr, args.getOrElse(Nil))
+    "@" ~> expression ~ (argList ?) ~ defaultSuspend ^^ {
-  }
+      case expr ~ args ~ hasDefaultsSuspended =>
+        AstApply(expr, args.getOrElse(Nil), hasDefaultsSuspended)
+    }
+
+  def defaultSuspend: Parser[Boolean] =
+    ("..." ?) ^^ ({
+      case Some(_) => true
+      case None    => false
+    })
 
   def assignment: Parser[AstAssignment] = ident ~ ("=" ~> expression) ^^ {
     case v ~ exp => AstAssignment(v, exp)

Interpreter/src/test/scala/org/enso/interpreter/CurryingTest.scala

@@ -14,4 +14,34 @@ class CurryingTest extends LanguageTest {
         |""".stripMargin
     eval(code) shouldEqual 11
   }
+
+  "Functions" should "allow default arguments to be suspended" in {
+    val code =
+      """
+        |@{
+        |  fn = { |w, x, y = 10, z = 20| (w + x) + (y + z) };
+        |
+        |  fn1 = @fn ...;
+        |  fn2 = @fn1 [1, 2] ...;
+        |  fn3 = @fn2 [3] ...;
+        |
+        |  @fn3
+        |}
+        |""".stripMargin
+
+    eval(code) shouldEqual 26
+  }
+
+  "Functions" should "allow defaults to be suspended in application chains" in {
+    val code =
+      """
+        |@{
+        |  fn = { |w, x, y = 10, z = 20| (w + x) + (y + z) };
+        |
+        |  @(@fn [3, 6] ...) [3]
+        |}
+        |""".stripMargin
+
+    eval(code) shouldEqual 32
+  }
 }