Type.Atom... yields Meta.AtomConstructor

distribution/lib/Standard/Base/0.0.0-dev/src/Internal/Meta_Helpers.enso

@@ -15,7 +15,7 @@ is_same_object_builtin value_1 value_2 = @Builtin_Method "Meta.is_same_object"
 is_a_builtin value typ = @Builtin_Method "Meta.is_a"
 type_of_builtin value = @Builtin_Method "Meta.type_of"
 get_annotation_builtin target method parameter_name = @Builtin_Method "Meta.get_annotation"
-is_atom_constructor_builtin value = @Builtin_Method "Meta.is_atom_constructor"
+find_atom_constructor_builtin value = @Builtin_Method "Meta.find_atom_constructor"
 is_atom_builtin value = @Builtin_Method "Meta.is_atom"
 is_error_builtin value = @Builtin_Method "Meta.is_error"
 is_type_builtin value = @Builtin_Method "Meta.is_type"

distribution/lib/Standard/Base/0.0.0-dev/src/Meta.enso

@@ -299,13 +299,15 @@ atom_with_hole factory = @Tail_Call Meta_Helpers.atom_with_hole_builtin factory
    Arguments:
    - value: The runtime entity to get the meta representation of.
 meta : Any -> Atom | Constructor | Primitive | Polyglot | Unresolved_Symbol | Error
-meta value = if Meta_Helpers.is_atom_builtin value then Atom.Value value else
-    if Meta_Helpers.is_atom_constructor_builtin value then Constructor.Value value else
-        if Meta_Helpers.is_polyglot_builtin value then Polyglot.Value value else
-            if Meta_Helpers.is_unresolved_symbol_builtin value then Unresolved_Symbol.Value value else
-                if Meta_Helpers.is_error_builtin value then Error.Value value.catch else
-                    if Meta_Helpers.is_type_builtin value then Type.Value value.catch else
-                        Primitive.Value value
+meta ~value =
+    ac = Meta_Helpers.find_atom_constructor_builtin value...
+    if ac.is_nothing.not then Constructor.Value ac else
+        if Meta_Helpers.is_atom_builtin value... then Atom.Value value else
+            if Meta_Helpers.is_polyglot_builtin value then Polyglot.Value value else
+                if Meta_Helpers.is_unresolved_symbol_builtin value then Unresolved_Symbol.Value value else
+                    if Meta_Helpers.is_error_builtin value then Error.Value value.catch else
+                        if Meta_Helpers.is_type_builtin value then Type.Value value.catch else
+                            Primitive.Value value
 
 ## PRIVATE
    ADVANCED
@@ -379,7 +381,7 @@ type Language
    Arguments:
    - value: The value to check.
 is_atom_constructor : Any -> Boolean
-is_atom_constructor value = @Tail_Call Meta_Helpers.is_atom_constructor_builtin value
+is_atom_constructor ~value = Meta_Helpers.find_atom_constructor_builtin value . is_nothing . not
 
 ## PRIVATE
 

engine/runtime/src/main/java/org/enso/interpreter/node/callable/thunk/ThunkExecutorNode.java

@@ -35,6 +35,11 @@ public static ThunkExecutorNode build() {
     return ThunkExecutorNodeGen.create();
   }
 
+  @NeverDefault
+  public static ThunkExecutorNode getUncached() {
+    return ThunkExecutorNodeGen.getUncached();
+  }
+
   /**
    * Forces the thunk to its resulting value.
    *

engine/runtime/src/main/java/org/enso/interpreter/node/expression/builtin/meta/FindAtomConstructorNode.java

@@ -0,0 +1,54 @@
+package org.enso.interpreter.node.expression.builtin.meta;
+
+import com.oracle.truffle.api.frame.VirtualFrame;
+import com.oracle.truffle.api.nodes.Node;
+import org.enso.interpreter.dsl.AcceptsError;
+import org.enso.interpreter.dsl.BuiltinMethod;
+import org.enso.interpreter.dsl.Suspend;
+import org.enso.interpreter.node.BaseNode;
+import org.enso.interpreter.node.MethodRootNode;
+import org.enso.interpreter.node.callable.thunk.ThunkExecutorNode;
+import org.enso.interpreter.runtime.EnsoContext;
+import org.enso.interpreter.runtime.callable.function.Function;
+import org.enso.interpreter.runtime.data.EnsoObject;
+import org.enso.interpreter.runtime.data.atom.AtomConstructor;
+import org.enso.interpreter.runtime.state.State;
+
+@BuiltinMethod(
+    type = "Meta",
+    name = "find_atom_constructor",
+    description = "Checks if the argument is a constructor.",
+    autoRegister = false)
+final class FindAtomConstructorNode extends Node {
+  EnsoObject execute(VirtualFrame frame, @Suspend @AcceptsError Object value, State state) {
+    var ac = findConstructor(value, frame, state);
+    if (ac != null) {
+      return ac;
+    } else {
+      var ctx = EnsoContext.get(this);
+      return ctx.getNothing();
+    }
+  }
+
+  static AtomConstructor findConstructor(Object value, VirtualFrame frame, State state) {
+    for (; ; ) {
+      if (value instanceof AtomConstructor atom) {
+        return atom;
+      }
+      if (value instanceof Function fn) {
+        if (AtomConstructor.accessorFor(fn) instanceof AtomConstructor atom) {
+          return atom;
+        }
+        if (MethodRootNode.constructorFor(fn) instanceof AtomConstructor atom) {
+          return atom;
+        }
+        if (fn.isThunk()) {
+          var thunkSolver = ThunkExecutorNode.getUncached();
+          value = thunkSolver.executeThunk(frame, value, state, BaseNode.TailStatus.NOT_TAIL);
+          continue;
+        }
+      }
+      return null;
+    }
+  }
+}

engine/runtime/src/main/java/org/enso/interpreter/runtime/data/atom/Atom.java

@@ -58,8 +58,10 @@ public abstract class Atom extends EnsoObject {
    * Creates a new Atom for a given constructor.
    *
    * @param constructor the Atom's constructor
+   * @param skipCheck don't assert whether the arity is non-zero
    */
-  Atom(AtomConstructor constructor) {
+  Atom(AtomConstructor constructor, boolean skipCheck) {
+    assert skipCheck || constructor.getArity() != 0;
     this.constructor = constructor;
   }
 

engine/runtime/src/main/java/org/enso/interpreter/runtime/data/atom/BoxingAtom.java

@@ -48,12 +48,12 @@ static NodeFactory<UnboxingAtom.FieldSetterNode>[] getFieldSetterNodeFactories(i
   private final Object[] fields;
 
   private BoxingAtom(AtomConstructor constructor, Object[] fields) {
-    super(constructor);
+    super(constructor, false);
     this.fields = fields;
   }
 
   private BoxingAtom(AtomConstructor constructor) {
-    super(constructor);
+    super(constructor, true);
     this.fields = NO_FIELDS;
   }
 
@@ -101,7 +101,11 @@ private static class InstantiatorNode extends UnboxingAtom.InstantiatorNode {
     @Override
     public Atom execute(AtomConstructor constructor, Layout layout, Object[] args) {
       assert constructor.getBoxedLayout() == layout;
-      return new BoxingAtom(constructor, args);
+      if (args.length == 0) {
+        return constructor.newInstance(new Object[0]);
+      } else {
+        return new BoxingAtom(constructor, args);
+      }
     }
   }
 

engine/runtime/src/main/java/org/enso/interpreter/runtime/data/atom/QualifiedAccessorNode.java

@@ -54,7 +54,7 @@ public Object execute(VirtualFrame frame) {
       } else if (atomConstructor == falseCtor) {
         return false;
       } else {
-        return atomConstructor.newInstance();
+        return atomConstructor.getConstructorFunction();
       }
     } else {
       return atomConstructor;

engine/runtime/src/main/java/org/enso/interpreter/runtime/data/atom/UnboxingAtom.java

@@ -60,7 +60,7 @@ abstract class UnboxingAtom extends Atom {
   protected final Layout layout;
 
   protected UnboxingAtom(AtomConstructor constructor, Layout layout) {
-    super(constructor);
+    super(constructor, false);
     this.layout = layout;
   }
 

test/Base_Tests/src/Data/Time/Date_Range_Spec.enso

@@ -152,7 +152,9 @@ add_specs suite_builder =
                 r.is_empty . should_equal r.to_vector.is_empty
                 r.not_empty . should_equal r.to_vector.not_empty
 
-                r.map .day_of_week . should_equal (r.to_vector.map .day_of_week)
+                x = r.map .day_of_week
+                y = r.to_vector.map .day_of_week
+                x . should_equal y
                 p = d-> d.day_of_week == Day_Of_Week.Monday
                 r.filter p . should_equal (r.to_vector.filter p)
                 r.partition p . should_equal (r.to_vector.partition p)

test/Base_Tests/src/Semantic/Meta_Spec.enso

@@ -47,6 +47,7 @@ test_method a b = a + b
 
 type Test_Type
     Value x
+    No_Value
 
 type Sum_Type
     Variant_A x
@@ -350,6 +351,22 @@ add_specs suite_builder =
             Meta.get_annotation My_Type .Value "bar" . should_equal Nothing
             Meta.get_annotation My_Type .Value "baz" . should_equal (My_Type.Value 1 2 3)
 
+        group_builder.specify "atom constructor with suspended evalution" <|
+            m = Meta.meta (Test_Type.No_Value...)
+            case m of
+                ac : Meta.Constructor ->
+                    ac.name . should_equal "No_Value"
+                _ ->
+                    Test.fail "Expecting Meta.Constructor, but was: "+m.to_text
+
+        group_builder.specify "atom without suspended evalution" <|
+            m = Meta.meta Test_Type.No_Value
+            case m of
+                a : Meta.Atom ->
+                    a.constructor.name . should_equal "No_Value"
+                _ ->
+                    Test.fail "Expecting Meta.Constructor, but was: "+m.to_text
+
     suite_builder.group "Check Nothing and NaN" group_builder->
         group_builder.specify "Nothing.is_a Nothing" <|
             Nothing.is_a Nothing . should_be_true