Fix the Array Visualisation

distribution/std-lib/Standard/src/Base.enso

@@ -1,4 +1,5 @@
 import Standard.Base.Data.Any.Extensions
+import Standard.Base.Data.Array.Extensions
 import Standard.Base.Data.Interval
 import Standard.Base.Data.Json
 import Standard.Base.Data.List
@@ -34,6 +35,7 @@ export Standard.Base.Meta
 export Standard.Base.System.File
 
 from Standard.Base.Data.Any.Extensions export all
+from Standard.Base.Data.Array.Extensions export all
 from Standard.Base.Data.List export Nil, Cons
 from Standard.Base.Data.Number.Extensions export all hiding Math, String, Double
 from Standard.Base.Data.Noise export all hiding Noise

distribution/std-lib/Standard/src/Base/Data/Array/Extensions.enso

@@ -0,0 +1,8 @@
+from Standard.Base import all
+
+## Transform the array into text for displaying as part of its default
+   visualization.
+Array.to_default_visualization_data : Text
+Array.to_default_visualization_data = 
+    Vector.Vector this . to_default_visualization_data
+

distribution/std-lib/Standard/src/Base/Data/Json.enso

@@ -81,6 +81,10 @@ type Json
    Check the `message` field for detailed information on the specific failure.
 type Parse_Error message
 
+## Converts the error to a display representation.
+Parse_Error.to_display_text : Text
+Parse_Error.to_display_text = "Parse error in parsing JSON: " + this.message.to_text + "."
+
 ## Gets the value associated with the given key in this object. Returns
    `Nothing` if the associated key is not defined.
 Object.get : Text -> Json | Nothing
@@ -110,6 +114,15 @@ type Marshalling_Error
        when the JSON does not contain all the fields required by the atom.
     type Missing_Field_Error json field format
 
+    to_display_text : Text
+    to_display_text = case this of
+        Type_Mismatch_Error json format ->
+            json_text = Meta.type_to_display_text json
+            format_text = Meta.type_to_display_text format
+            "Type mismatch error: the json with type `" + json_text + "` did not match the format `" + format_text + "`."
+        Missing_Field_Error _ field _ ->
+            "Missing field in Json: the field `" + field.to_text "` was missing in the json."
+
 ## Generically converts an atom into a JSON object.
 
    The input atom is converted into a JSON object, with a `"type"` field set to

distribution/std-lib/Standard/src/Base/Data/Vector.enso

@@ -523,6 +523,13 @@ type Vector
 
         Vector new_vec_arr
 
+    ## Transform the vector into text for displaying as part of its default
+       visualization.
+    to_default_visualization_data : Text
+    to_default_visualization_data =
+        json = this.take_start 100 . to_json
+        json.to_text
+
 ## A builder type for Enso vectors.
 
    A vector builder is a mutable data structure, that allows to gather a

distribution/std-lib/Standard/src/Base/Meta.enso

@@ -147,3 +147,10 @@ is_same_object value_1 value_2 = Builtins.Meta.is_same_object value_1 value_2
 get_source_location : Integer -> Text
 get_source_location skip_frames =
     Builtins.Meta.get_source_location skip_frames+1
+
+## Displays the type of the provided value as text.
+
+   Arguments:
+   - value: The value for which to display the type.
+type_to_display_text : Any -> Text
+type_to_display_text value = Builtins.Meta.type_to_display_text value

distribution/std-lib/Standard/src/Base/System/File.enso

@@ -300,7 +300,7 @@ new path = File (Prim_Io.get_file path)
 
    > Example
      Read the `data.csv` file in the project directory.
-         File.open (Enso_Project.data / "data.csv")
+         File.read (Enso_Project.data / "data.csv")
 read : Text -> Text
 read path = (here.new path).read
 

distribution/std-lib/Standard/src/Test.enso

@@ -179,8 +179,8 @@ run_spec ~behavior =
         case ex of
             Failure _ -> ex
             Finished_With_Error err stack_trace_text ->
-                Failure ("An unexpected error was returned: " + err.to_text + '\n' + stack_trace_text)
-            _ -> Failure ("An unexpected panic was thrown: " + ex.to_text + '\n' + maybeExc.get_stack_trace_text)
+                Failure ("An unexpected error was returned: " + err.to_display_text + '\n' + stack_trace_text)
+            _ -> Failure ("An unexpected panic was thrown: " + ex.to_display_text + '\n' + maybeExc.get_stack_trace_text)
     result
 
 ## Creates a new test group, desribing properties of the object

engine/polyglot-api/src/main/java/org/enso/polyglot/MethodNames.java

@@ -3,26 +3,27 @@
 /** Container for polyglot method names */
 public class MethodNames {
   public static class TopScope {
-    public static final String GET_MODULE = "get_module";
     public static final String CREATE_MODULE = "create_module";
+    public static final String GET_MODULE = "get_module";
+    public static final String LEAK_CONTEXT = "leak_context";
     public static final String REGISTER_MODULE = "register_module";
     public static final String UNREGISTER_MODULE = "unregister_module";
-    public static final String LEAK_CONTEXT = "leak_context";
   }
 
   public static class Module {
+    public static final String EVAL_EXPRESSION = "eval_expression";
     public static final String GET_ASSOCIATED_CONSTRUCTOR = "get_associated_constructor";
-    public static final String GET_METHOD = "get_method";
     public static final String GET_CONSTRUCTOR = "get_constructor";
+    public static final String GET_METHOD = "get_method";
+    public static final String GET_NAME = "get_name";
     public static final String REPARSE = "reparse";
     public static final String SET_SOURCE = "set_source";
     public static final String SET_SOURCE_FILE = "set_source_file";
-    public static final String EVAL_EXPRESSION = "eval_expression";
   }
 
   public static class Function {
     public static final String EQUALS = "equals";
-    public static final String GET_SOURCE_START = "get_source_start";
     public static final String GET_SOURCE_LENGTH = "get_source_length";
+    public static final String GET_SOURCE_START = "get_source_start";
   }
 }

engine/polyglot-api/src/main/scala/org/enso/polyglot/Module.scala

@@ -9,12 +9,17 @@ import org.graalvm.polyglot.Value
 class Module(private val value: Value) {
   import MethodNames.Module._
 
+  /** @return the name of the module
+    */
+  def getName: String = value.invokeMember(GET_NAME).asString()
+
   /** @return the associated type of this module
     */
   def getAssociatedConstructor: Value =
     value.invokeMember(GET_ASSOCIATED_CONSTRUCTOR)
 
-  /** Gets a constructor definition by name
+  /** Gets a constructor definition by name.
+   *
     * @param name the constructor name
     * @return the polyglot representation of the constructor.
     */
@@ -27,11 +32,17 @@ class Module(private val value: Value) {
     * @param name the name of the method
     * @return the runtime representation of the method
     */
-  def getMethod(constructor: Value, name: String): Function =
-    new Function(value.invokeMember(GET_METHOD, constructor, name))
+  def getMethod(constructor: Value, name: String): Option[Function] = {
+    val newVal = value.invokeMember(GET_METHOD, constructor, name);
+    if (newVal.isNull) { None }
+    else {
+      Some(new Function(newVal))
+    }
+  }
 
   /** Evaluates an arbitrary expression as if it were placed in a function
     * body inside this module.
+   *
     * @param code the expression to evaluate
     * @return the return value of the expression
     */

engine/runner/src/main/scala/org/enso/runner/Main.scala

@@ -1,8 +1,5 @@
 package org.enso.runner
 
-import java.io.File
-import java.util.UUID
-
 import akka.http.scaladsl.model.{IllegalUriException, Uri}
 import cats.implicits._
 import org.apache.commons.cli.{Option => CliOption, _}
@@ -12,8 +9,11 @@ import org.enso.loggingservice.LogLevel
 import org.enso.pkg.{Contact, PackageManager, SemVerEnsoVersion}
 import org.enso.polyglot.{LanguageInfo, Module, PolyglotContext}
 import org.enso.version.VersionDescription
-import org.graalvm.polyglot.{PolyglotException, Value}
+import org.graalvm.polyglot.PolyglotException
 
+import java.io.File
+import java.util.UUID
+import scala.Console.err
 import scala.jdk.CollectionConverters._
 import scala.util.Try
 
@@ -382,11 +382,18 @@ object Main {
     mainModule: Module,
     rootPkgPath: Option[File],
     mainMethodName: String = "main"
-  ): Value = {
+  ): Unit = {
     val mainCons = mainModule.getAssociatedConstructor
     val mainFun  = mainModule.getMethod(mainCons, mainMethodName)
     try {
-      mainFun.execute(mainCons.newInstance())
+      mainFun match {
+        case Some(main) => main.execute(mainCons.newInstance())
+        case None =>
+          err.println(
+            s"The module ${mainModule.getName} does not contain a `main` " +
+            s"function. It could not be run."
+          )
+      }
     } catch {
       case e: PolyglotException =>
         printPolyglotException(e, rootPkgPath)

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

@@ -0,0 +1,16 @@
+package org.enso.interpreter.node.expression.builtin.meta;
+
+import com.oracle.truffle.api.CompilerDirectives.CompilationFinal;
+import com.oracle.truffle.api.nodes.Node;
+import org.enso.interpreter.dsl.BuiltinMethod;
+import org.enso.interpreter.node.expression.builtin.text.util.TypeToDisplayTextNode;
+import org.enso.interpreter.runtime.data.text.Text;
+
+@BuiltinMethod(type = "Meta", name = "type_to_display_text", description = "Pretty prints a type.")
+public class DisplayTypeNode extends Node {
+  @Child @CompilationFinal TypeToDisplayTextNode displayTypeNode = TypeToDisplayTextNode.build();
+
+  Text execute(Object _this, Object value) {
+    return Text.create(displayTypeNode.execute(value));
+  }
+}

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

@@ -1,6 +1,5 @@
 package org.enso.interpreter.node.expression.builtin.meta;
 
-import com.oracle.truffle.api.dsl.Cached;
 import com.oracle.truffle.api.dsl.CachedContext;
 import com.oracle.truffle.api.dsl.Specialization;
 import com.oracle.truffle.api.nodes.Node;

engine/runtime/src/main/java/org/enso/interpreter/node/expression/builtin/text/util/TypeToDisplayTextNode.java

@@ -13,6 +13,15 @@
 public abstract class TypeToDisplayTextNode extends Node {
   public abstract String execute(Object o);
 
+  /**
+   * Create a node that can display types as text.
+   *
+   * @return a new type display node
+   */
+  public static TypeToDisplayTextNode build() {
+    return TypeToDisplayTextNodeGen.create();
+  }
+
   @Specialization
   @CompilerDirectives.TruffleBoundary
   String doDisplay(

engine/runtime/src/main/java/org/enso/interpreter/runtime/Module.java

@@ -15,6 +15,7 @@
 import java.io.File;
 import java.io.IOException;
 
+import java.util.Map;
 import org.enso.compiler.core.IR;
 import org.enso.compiler.phase.StubIrBuilder;
 import org.enso.interpreter.Language;
@@ -404,8 +405,11 @@ static Object doInvoke(
         throws UnknownIdentifierException, ArityException, UnsupportedTypeException {
       ModuleScope scope = module.compileScope(context);
       switch (member) {
+        case MethodNames.Module.GET_NAME:
+          return module.getName().toString();
         case MethodNames.Module.GET_METHOD:
-          return getMethod(scope, arguments);
+          Function result = getMethod(scope, arguments);
+          return result == null ? context.getBuiltins().nothing().newInstance() : result;
         case MethodNames.Module.GET_CONSTRUCTOR:
           return getConstructor(scope, arguments);
         case MethodNames.Module.REPARSE:

engine/runtime/src/main/java/org/enso/interpreter/runtime/builtin/Meta.java

@@ -18,6 +18,7 @@ public Meta(Language language, ModuleScope scope) {
     AtomConstructor meta = new AtomConstructor("Meta", scope).initializeFields();
     scope.registerConstructor(meta);
 
+    scope.registerMethod(meta, "type_to_display_text", DisplayTypeMethodGen.makeFunction(language));
     scope.registerMethod(
         meta, "is_unresolved_symbol", IsUnresolvedSymbolMethodGen.makeFunction(language));
     scope.registerMethod(
@@ -50,6 +51,7 @@ public Meta(Language language, ModuleScope scope) {
         meta, "get_polyglot_language", GetPolyglotLanguageMethodGen.makeFunction(language));
 
     scope.registerMethod(meta, "is_same_object", IsSameObjectMethodGen.makeFunction(language));
-    scope.registerMethod(meta, "get_source_location", GetSourceLocationMethodGen.makeFunction(language));
+    scope.registerMethod(
+        meta, "get_source_location", GetSourceLocationMethodGen.makeFunction(language));
   }
 }

engine/runtime/src/main/resources/Builtins.enso

@@ -224,7 +224,7 @@ type Error
     catch_primitive : (Error -> Any) -> Any
     catch_primitive handler = @Builtin_Method "Any.catch"
 
-    ## PRIVATE 
+    ## PRIVATE
        UNSTABLE
 
        Returns a textual representation of the stack trace attached to an error.
@@ -728,8 +728,16 @@ type Meta
        Arguments:
        - frames_to_skip: how many frames on the stack to skip. Called with 0
          will return exact location of the call.
-   get_source_location : Integer -> Text
-   get_source_location frames_to_skip = @Builtin_Method "Meta.get_source_location"
+    get_source_location : Integer -> Text
+    get_source_location frames_to_skip = @Builtin_Method "Meta.get_source_location"
+
+    ## Pretty-prints the type of the provided value using the interpreter's
+       internal logic for printing types.
+
+       Arguments:
+       - value: The value whose type should be printed.
+    type_to_display_text : Any -> Text
+    type_to_display_text value = @Builtin_Method "Meta.display_type"
 
 ## Utilities for working with primitive arrays.
 type Array

engine/runtime/src/main/scala/org/enso/compiler/core/IR.scala

@@ -1,16 +1,15 @@
 package org.enso.compiler.core
 
-import java.util.UUID
-
 import org.enso.compiler.core.IR.{Expression, IdentifiedLocation}
-import org.enso.compiler.core.ir.{DiagnosticStorage, MetadataStorage}
 import org.enso.compiler.core.ir.MetadataStorage.MetadataPair
+import org.enso.compiler.core.ir.{DiagnosticStorage, MetadataStorage}
 import org.enso.compiler.data.BindingsMap
 import org.enso.compiler.exception.CompilerError
 import org.enso.compiler.pass.IRPass
 import org.enso.interpreter.epb.EpbParser
 import org.enso.syntax.text.{AST, Debug, Location}
 
+import java.util.UUID
 import scala.annotation.unused
 
 /** [[IR]] is a temporary and fairly unsophisticated internal representation
@@ -5337,7 +5336,10 @@ object IR {
   // === Errors ===============================================================
 
   /** A trait for all errors in Enso's IR. */
-  sealed trait Error extends Expression with Diagnostic {
+  sealed trait Error
+      extends Expression
+      with IR.Module.Scope.Definition
+      with Diagnostic {
     override def mapExpressions(fn: Expression => Expression):      Error
     override def setLocation(location: Option[IdentifiedLocation]): Error
     override def duplicate(

engine/runtime/src/main/scala/org/enso/compiler/pass/desugar/ComplexType.scala

@@ -169,6 +169,7 @@ case object ComplexType extends IRPass {
         matchSignaturesAndGenerate(name, binding)
       case funSugar @ IR.Function.Binding(name, _, _, _, _, _, _) =>
         matchSignaturesAndGenerate(name, funSugar)
+      case err: IR.Error => Seq(err)
       case _ =>
         throw new CompilerError("Unexpected IR node in complex type body.")
     }

engine/runtime/src/test/scala/org/enso/compiler/test/pass/desugar/ComplexTypeTest.scala

@@ -209,4 +209,42 @@ class ComplexTypeTest extends CompilerTest {
         .name shouldEqual "bad_trailing_sig"
     }
   }
+
+  "Invalid complex types" should {
+    implicit val ctx: ModuleContext = mkModuleContext
+
+    val ir =
+      """
+        |type Foo
+        |    Bar
+        |    type Baz
+        |
+        |    g a = this + a
+        |
+        |    f a =
+        |""".stripMargin.preprocessModule.desugar
+
+    "have their types translated untouched" in {
+      ir.bindings.head shouldBe a[Definition.Atom]
+      val atom = ir.bindings.head.asInstanceOf[Definition.Atom]
+      atom.name.name shouldEqual "Baz"
+    }
+
+    "have their errors translated untouched" in {
+      ir.bindings.last shouldBe an[IR.Error.Syntax]
+      val err = ir.bindings.last.asInstanceOf[IR.Error.Syntax]
+      err.reason shouldBe an[IR.Error.Syntax.UnexpectedDeclarationInType.type]
+    }
+
+    "have their valid methods desugared" in {
+      ir.bindings(1) shouldBe a[Definition.Method.Binding]
+      ir.bindings(2) shouldBe a[Definition.Method.Binding]
+      val methodOnBar = ir.bindings(1).asInstanceOf[Definition.Method.Binding]
+      val methodOnBaz = ir.bindings(2).asInstanceOf[Definition.Method.Binding]
+      methodOnBar.typeName.name shouldEqual "Bar"
+      methodOnBar.methodName.name shouldEqual "g"
+      methodOnBaz.typeName.name shouldEqual "Baz"
+      methodOnBaz.methodName.name shouldEqual "g"
+    }
+  }
 }