Follow up for trace pretty printing (#1227)

bench/src/jmh/java/org/pkl/core/ListSort.java

@@ -23,6 +23,7 @@ import java.util.concurrent.TimeUnit;
 import org.openjdk.jmh.annotations.*;
 import org.openjdk.jmh.util.TempFile;
 import org.openjdk.jmh.util.TempFileManager;
+import org.pkl.core.evaluatorSettings.TraceMode;
 import org.pkl.core.http.HttpClient;
 import org.pkl.core.module.ModuleKeyFactories;
 import org.pkl.core.repl.ReplRequest;
@@ -52,7 +53,7 @@ public class ListSort {
           IoUtils.getCurrentWorkingDir(),
           StackFrameTransformers.defaultTransformer,
           false,
-          null);
+          TraceMode.COMPACT);
   private static final List<Object> list = new ArrayList<>(100000);
 
   static {

docs/src/test/kotlin/DocSnippetTests.kt

@@ -15,6 +15,7 @@ import org.pkl.commons.test.FileTestUtils.rootProjectDir
 import org.pkl.core.Loggers
 import org.pkl.core.SecurityManagers
 import org.pkl.core.StackFrameTransformers
+import org.pkl.core.evaluatorSettings.TraceMode
 import org.pkl.core.module.ModuleKeyFactories
 import org.pkl.core.repl.ReplRequest
 import org.pkl.core.repl.ReplResponse
@@ -97,7 +98,7 @@ class DocSnippetTestsEngine : HierarchicalTestEngine<DocSnippetTestsEngine.Execu
       IoUtils.getCurrentWorkingDir(),
       StackFrameTransformers.defaultTransformer,
       false,
-      null
+      TraceMode.COMPACT,
     )
     return ExecutionContext(replServer)
   }

pkl-cli/src/main/kotlin/org/pkl/cli/CliRepl.kt

@@ -19,6 +19,7 @@ import org.pkl.cli.repl.Repl
 import org.pkl.commons.cli.CliCommand
 import org.pkl.core.Loggers
 import org.pkl.core.SecurityManagers
+import org.pkl.core.evaluatorSettings.TraceMode
 import org.pkl.core.module.ModuleKeyFactories
 import org.pkl.core.module.ModulePathResolver
 import org.pkl.core.repl.ReplServer
@@ -68,7 +69,7 @@ internal class CliRepl(private val options: CliEvaluatorOptions) : CliCommand(op
           options.base.normalizedWorkingDir,
           stackFrameTransformer,
           options.base.color?.hasColor() ?: false,
-          options.base.traceMode,
+          options.base.traceMode ?: TraceMode.COMPACT,
         )
       Repl(options.base.normalizedWorkingDir, server).run()
     }

pkl-cli/src/test/kotlin/org/pkl/cli/repl/ReplMessagesTest.kt

@@ -21,6 +21,7 @@ import org.pkl.commons.toPath
 import org.pkl.core.Loggers
 import org.pkl.core.SecurityManagers
 import org.pkl.core.StackFrameTransformers
+import org.pkl.core.evaluatorSettings.TraceMode
 import org.pkl.core.http.HttpClient
 import org.pkl.core.module.ModuleKeyFactories
 import org.pkl.core.repl.ReplRequest
@@ -43,7 +44,7 @@ class ReplMessagesTest {
       "/".toPath(),
       StackFrameTransformers.defaultTransformer,
       false,
-      null,
+      TraceMode.COMPACT,
     )
 
   @Test

pkl-commons-cli/src/main/kotlin/org/pkl/commons/cli/commands/BaseOptions.kt

@@ -295,16 +295,15 @@ class BaseOptions : OptionGroup() {
       .multiple()
       .toMap()
 
-  val traceMode: TraceMode by
+  val traceMode: TraceMode? by
     option(
         names = arrayOf("--trace-mode"),
-        metavar = "when",
+        metavar = "style",
         help =
-          "Specifies how calls to trace() are formatted. Possible values of <when> are 'default', 'pretty' and 'hidden'.",
+          "Specifies how calls to trace() are formatted. Possible values of <style> are 'compact' and 'pretty'.",
       )
       .enum<TraceMode> { it.name.lowercase() }
       .single()
-      .default(TraceMode.DEFAULT)
 
   // hidden option used by native tests
   private val testPort: Int by

pkl-core/src/main/java/org/pkl/core/Analyzer.java

@@ -57,7 +57,7 @@ public class Analyzer {
       @Nullable Path moduleCacheDir,
       @Nullable DeclaredDependencies projectDependencies,
       HttpClient httpClient,
-      @Nullable TraceMode traceMode) {
+      TraceMode traceMode) {
     this.transformer = transformer;
     this.color = color;
     this.securityManager = securityManager;

pkl-core/src/main/java/org/pkl/core/EvaluatorBuilder.java

@@ -68,7 +68,7 @@ public final class EvaluatorBuilder {
 
   private @Nullable DeclaredDependencies dependencies;
 
-  private @Nullable TraceMode traceMode;
+  private TraceMode traceMode = TraceMode.COMPACT;
 
   private EvaluatorBuilder() {}
 

pkl-core/src/main/java/org/pkl/core/EvaluatorImpl.java

@@ -82,7 +82,7 @@ public class EvaluatorImpl implements Evaluator {
       @Nullable Path moduleCacheDir,
       @Nullable DeclaredDependencies projectDependencies,
       @Nullable String outputFormat,
-      @Nullable TraceMode traceMode) {
+      TraceMode traceMode) {
 
     securityManager = manager;
     frameTransformer = transformer;

pkl-core/src/main/java/org/pkl/core/Loggers.java

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2024 Apple Inc. and the Pkl project authors. All rights reserved.
+ * Copyright © 2024-2025 Apple Inc. and the Pkl project authors. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -80,6 +80,13 @@ public final class Loggers {
   }
 
   private static String formatMessage(String level, String message, StackFrame frame) {
-    return "pkl: " + level + ": " + message + " (" + frame.getModuleUri() + ')';
+    return "pkl: "
+        + level
+        + ": "
+        + message
+        + (message.endsWith("\n") ? "" : " ")
+        + "("
+        + frame.getModuleUri()
+        + ')';
   }
 }

pkl-core/src/main/java/org/pkl/core/ast/expression/unary/TraceNode.java

@@ -18,8 +18,9 @@ package org.pkl.core.ast.expression.unary;
 import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
 import com.oracle.truffle.api.frame.VirtualFrame;
 import com.oracle.truffle.api.source.SourceSection;
+import java.util.Arrays;
+import java.util.stream.Collectors;
 import org.pkl.core.ast.ExpressionNode;
-import org.pkl.core.evaluatorSettings.TraceMode;
 import org.pkl.core.runtime.*;
 
 public final class TraceNode extends ExpressionNode {
@@ -27,9 +28,8 @@ public final class TraceNode extends ExpressionNode {
 
   private static final int MAX_RENDERER_LENGTH = 1000000;
 
-  private final VmValueRenderer singleLineRenderer =
+  private final VmValueRenderer compactRenderer = VmValueRenderer.singleLine(MAX_RENDERER_LENGTH);
-      VmValueRenderer.singleLine(MAX_RENDERER_LENGTH);
+  private final VmValueRenderer prettyRenderer = VmValueRenderer.multiLine(Integer.MAX_VALUE);
-  private final VmValueRenderer multiLineRenderer = VmValueRenderer.multiLine(MAX_RENDERER_LENGTH);
 
   public TraceNode(SourceSection sourceSection, ExpressionNode valueNode) {
     super(sourceSection);
@@ -45,29 +45,23 @@ public final class TraceNode extends ExpressionNode {
 
   @TruffleBoundary
   private void doTrace(Object value, VmContext context) {
-    // If traces are disabled, returns early.
+    VmValue.force(value, true);
-    if (context.getTraceMode() == TraceMode.HIDDEN) {
-      return;
-    }
-    if (value instanceof VmObjectLike objectLike) {
-      try {
-        objectLike.force(true, true);
-      } catch (VmException ignored) {
-      }
-    }
-
     var sourceSection = valueNode.getSourceSection();
-    String renderedValue;
+    var lhs = sourceSection.isAvailable() ? sourceSection.getCharacters().toString() : "<value>";
-    if (context.getTraceMode() == TraceMode.PRETTY) {
-      renderedValue = multiLineRenderer.render(value);
-    } else {
-      renderedValue = singleLineRenderer.render(value);
-    }
     var message =
-        (sourceSection.isAvailable() ? sourceSection.getCharacters() : "<value")
+        switch (context.getTraceMode()) {
-            + " = "
+          case COMPACT -> lhs + " = " + compactRenderer.render(value);
-            + renderedValue;
+          case PRETTY -> {
-
+            var rhs = prettyRenderer.render(value);
+            yield (lhs.contains("\n") ? "\n" + addIndent(lhs, "  ") + "\n=" : lhs + " =")
+                + (rhs.contains("\n") ? "\n" + addIndent(rhs, "  ") : " " + rhs)
+                + "\n";
+          }
+        };
     context.getLogger().trace(message, VmUtils.createStackFrame(sourceSection, null));
   }
+
+  private static String addIndent(String s, String indent) {
+    return Arrays.stream(s.split("\n")).map((it) -> indent + it).collect(Collectors.joining("\n"));
+  }
 }

pkl-core/src/main/java/org/pkl/core/evaluatorSettings/TraceMode.java

@@ -17,10 +17,8 @@ package org.pkl.core.evaluatorSettings;
 
 /** Dictates the rendering of calls to the trace() method within Pkl. */
 public enum TraceMode {
-  /** All trace() calls will not be emitted to stderr. */
-  HIDDEN,
   /** All structures passed to trace() will be emitted on a single line. */
-  DEFAULT,
+  COMPACT,
   /** All structures passed to trace() will be indented and emitted across multiple lines. */
   PRETTY
 }

pkl-core/src/main/java/org/pkl/core/repl/ReplServer.java

@@ -84,7 +84,7 @@ public class ReplServer implements AutoCloseable {
       Path workingDir,
       StackFrameTransformer frameTransformer,
       boolean color,
-      @Nullable TraceMode traceMode) {
+      TraceMode traceMode) {
 
     this.workingDir = workingDir;
     this.securityManager = securityManager;

pkl-core/src/main/java/org/pkl/core/runtime/StdLibModule.java

@@ -22,6 +22,7 @@ import java.util.Map;
 import org.pkl.core.Loggers;
 import org.pkl.core.SecurityManagers;
 import org.pkl.core.StackFrameTransformers;
+import org.pkl.core.evaluatorSettings.TraceMode;
 import org.pkl.core.http.HttpClient;
 import org.pkl.core.module.ModuleKeyFactories;
 import org.pkl.core.module.ModuleKeys;
@@ -50,7 +51,7 @@ public abstract class StdLibModule {
                       null,
                       null,
                       null,
-                      null));
+                      TraceMode.COMPACT));
               var language = VmLanguage.get(null);
               var moduleKey = ModuleKeys.standardLibrary(uri);
               var source = VmUtils.loadSource((ResolvedModuleKey) moduleKey);

pkl-core/src/main/java/org/pkl/core/runtime/VmContext.java

@@ -66,7 +66,7 @@ public final class VmContext {
         @Nullable String outputFormat,
         @Nullable PackageResolver packageResolver,
         @Nullable ProjectDependenciesManager projectDependenciesManager,
-        @Nullable TraceMode traceMode) {
+        TraceMode traceMode) {
 
       this.frameTransformer = frameTransformer;
       this.securityManager = securityManager;
@@ -148,7 +148,7 @@ public final class VmContext {
     return holder.projectDependenciesManager;
   }
 
-  public @Nullable TraceMode getTraceMode() {
+  public TraceMode getTraceMode() {
     return holder.traceMode;
   }
 }

pkl-core/src/test/files/LanguageSnippetTests/input/projects/compactTraceMode/PklProject

@@ -1,5 +1,5 @@
 amends "pkl:Project"
 
 evaluatorSettings {
-  traceMode = "default"
+  traceMode = "compact"
 }

pkl-core/src/test/files/LanguageSnippetTests/input/projects/hiddenTraceMode/PklProject

@@ -1,5 +0,0 @@
-amends "pkl:Project"
-
-evaluatorSettings {
-  traceMode = "hidden"
-}

pkl-core/src/test/files/LanguageSnippetTests/input/projects/hiddenTraceMode/hiddenTraceMode.pkl

@@ -1,18 +0,0 @@
-amends ".../snippetTest.pkl"
-
-examples {
-  ["traceMode = 'hidden' results in no trace output"] {
-    trace(new {
-      ["Parrot"] {
-        name = "Parrot"
-        age = 1234
-        bucketSettings = new {
-          kicked = true
-          ["fjordConfig"] = new {
-            isPining = true
-          }
-        }
-      }
-    })
-  }
-}

pkl-core/src/test/files/LanguageSnippetTests/input/projects/prettyTraceMode/prettyTraceMode.pkl

@@ -1,7 +1,51 @@
 amends ".../snippetTest.pkl"
 
 examples {
-  ["traceMode = 'pretty' results in indented, multi-line output"] {
+  ["single-line lhs, single-line rhs"] {
+    let (val = new Dynamic {
+      ["Parrot"] {
+        name = "Parrot"
+        age = 1234
+        bucketSettings = new {
+          kicked = true
+          ["fjordConfig"] = new {
+            isPining = true
+          }
+        }
+      }
+    })
+      trace(val["Parrot"].name)
+  }
+  ["single-line lhs, multi-line rhs"] {
+    let (val = new Dynamic {
+      ["Parrot"] {
+        name = "Parrot"
+        age = 1234
+        bucketSettings = new {
+          kicked = true
+          ["fjordConfig"] = new {
+            isPining = true
+          }
+        }
+      }
+    })
+      trace(val)
+  }
+  ["multi-line lhs, single-line rhs"] {
+    trace((new Dynamic {
+      ["Parrot"] {
+        name = "Parrot"
+        age = 1234
+        bucketSettings = new {
+          kicked = true
+          ["fjordConfig"] = new {
+            isPining = true
+          }
+        }
+      }
+    })["Parrot"].name)
+  }
+  ["multi-line lhs, multi-line rhs"] {
     trace(new {
       ["Parrot"] {
         name = "Parrot"

pkl-core/src/test/files/LanguageSnippetTests/output/projects/compactTraceMode/compactTraceMode.err

@@ -25,4 +25,4 @@ pkl: TRACE: new {
           }
         }
       }
-    } = new Dynamic { ["Parrot"] { name = "Parrot"; age = 1234; bucketSettings { kicked = true; ["fjordConfig"] { isPining = true } } } } (file:///$snippetsDir/input/projects/defaultTraceMode/defaultTraceMode.pkl)
+    } = new Dynamic { ["Parrot"] { name = "Parrot"; age = 1234; bucketSettings { kicked = true; ["fjordConfig"] { isPining = true } } } } (file:///$snippetsDir/input/projects/compactTraceMode/compactTraceMode.pkl)

pkl-core/src/test/files/LanguageSnippetTests/output/projects/hiddenTraceMode/hiddenTraceMode.pcf

@@ -1,16 +0,0 @@
-examples {
-  ["traceMode = 'hidden' results in no trace output"] {
-    new {
-      ["Parrot"] {
-        name = "Parrot"
-        age = 1234
-        bucketSettings {
-          kicked = true
-          ["fjordConfig"] {
-            isPining = true
-          }
-        }
-      }
-    }
-  }
-}

pkl-core/src/test/files/LanguageSnippetTests/output/projects/prettyTraceMode/prettyTraceMode.err

@@ -1,5 +1,25 @@
 examples {
-  ["traceMode = 'pretty' results in indented, multi-line output"] {
+  ["single-line lhs, single-line rhs"] {
+    "Parrot"
+  }
+  ["single-line lhs, multi-line rhs"] {
+    new {
+      ["Parrot"] {
+        name = "Parrot"
+        age = 1234
+        bucketSettings {
+          kicked = true
+          ["fjordConfig"] {
+            isPining = true
+          }
+        }
+      }
+    }
+  }
+  ["multi-line lhs, single-line rhs"] {
+    "Parrot"
+  }
+  ["multi-line lhs, multi-line rhs"] {
     new {
       ["Parrot"] {
         name = "Parrot"
@@ -14,26 +34,61 @@ examples {
     }
   }
 }
-pkl: TRACE: new {
+pkl: TRACE: val["Parrot"].name = "Parrot"
-      ["Parrot"] {
+(file:///$snippetsDir/input/projects/prettyTraceMode/prettyTraceMode.pkl)
-        name = "Parrot"
+pkl: TRACE: val =
-        age = 1234
+  new Dynamic {
-        bucketSettings = new {
+    ["Parrot"] {
-          kicked = true
+      name = "Parrot"
-          ["fjordConfig"] = new {
+      age = 1234
-            isPining = true
+      bucketSettings {
-          }
+        kicked = true
+        ["fjordConfig"] {
+          isPining = true
         }
       }
-    } = new Dynamic {
-  ["Parrot"] {
-    name = "Parrot"
-    age = 1234
-    bucketSettings {
-      kicked = true
-      ["fjordConfig"] {
-        isPining = true
-      }
     }
   }
-} (file:///$snippetsDir/input/projects/prettyTraceMode/prettyTraceMode.pkl)
+(file:///$snippetsDir/input/projects/prettyTraceMode/prettyTraceMode.pkl)
+pkl: TRACE: 
+  (new Dynamic {
+        ["Parrot"] {
+          name = "Parrot"
+          age = 1234
+          bucketSettings = new {
+            kicked = true
+            ["fjordConfig"] = new {
+              isPining = true
+            }
+          }
+        }
+      })["Parrot"].name
+= "Parrot"
+(file:///$snippetsDir/input/projects/prettyTraceMode/prettyTraceMode.pkl)
+pkl: TRACE: 
+  new {
+        ["Parrot"] {
+          name = "Parrot"
+          age = 1234
+          bucketSettings = new {
+            kicked = true
+            ["fjordConfig"] = new {
+              isPining = true
+            }
+          }
+        }
+      }
+=
+  new Dynamic {
+    ["Parrot"] {
+      name = "Parrot"
+      age = 1234
+      bucketSettings {
+        kicked = true
+        ["fjordConfig"] {
+          isPining = true
+        }
+      }
+    }
+  }
+(file:///$snippetsDir/input/projects/prettyTraceMode/prettyTraceMode.pkl)

pkl-core/src/test/kotlin/org/pkl/core/AnalyzerTest.kt

@@ -23,6 +23,7 @@ import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.io.TempDir
 import org.pkl.commons.test.PackageServer
 import org.pkl.commons.writeString
+import org.pkl.core.evaluatorSettings.TraceMode
 import org.pkl.core.http.HttpClient
 import org.pkl.core.module.ModuleKeyFactories
 import org.pkl.core.project.Project
@@ -37,7 +38,7 @@ class AnalyzerTest {
       null,
       null,
       HttpClient.dummyClient(),
-      null,
+      TraceMode.COMPACT,
     )
 
   @Test
@@ -116,7 +117,7 @@ class AnalyzerTest {
         tempDir.resolve("packages"),
         null,
         HttpClient.dummyClient(),
-        null,
+        TraceMode.COMPACT,
       )
     PackageServer.populateCacheDir(tempDir.resolve("packages"))
     val file1 =
@@ -192,7 +193,7 @@ class AnalyzerTest {
         tempDir.resolve("packages"),
         project.dependencies,
         HttpClient.dummyClient(),
-        null,
+        TraceMode.COMPACT,
       )
     val file1 =
       tempDir
@@ -305,7 +306,7 @@ class AnalyzerTest {
         tempDir.resolve("packages"),
         project.dependencies,
         HttpClient.dummyClient(),
-        null,
+        TraceMode.COMPACT,
       )
     val result = analyzer.importGraph(mainPkl.toUri())
     val birdUri = URI("projectpackage://localhost:0/birds@1.0.0#/bird.pkl")

pkl-core/src/test/kotlin/org/pkl/core/ReplServerTest.kt

@@ -18,6 +18,7 @@ package org.pkl.core
 import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 import org.pkl.commons.toPath
+import org.pkl.core.evaluatorSettings.TraceMode
 import org.pkl.core.http.HttpClient
 import org.pkl.core.module.ModuleKeyFactories
 import org.pkl.core.repl.ReplRequest
@@ -45,7 +46,7 @@ class ReplServerTest {
       "/".toPath(),
       StackFrameTransformers.defaultTransformer,
       false,
-      null,
+      TraceMode.COMPACT,
     )
 
   @Test

pkl-server/src/main/kotlin/org/pkl/server/BinaryEvaluator.kt

@@ -40,7 +40,7 @@ internal class BinaryEvaluator(
   moduleCacheDir: Path?,
   declaredDependencies: DeclaredDependencies?,
   outputFormat: String?,
-  traceMode: TraceMode?,
+  traceMode: TraceMode,
 ) :
   EvaluatorImpl(
     transformer,

pkl-server/src/main/kotlin/org/pkl/server/Server.kt

@@ -25,6 +25,7 @@ import java.util.regex.Pattern
 import kotlin.random.Random
 import org.pkl.core.*
 import org.pkl.core.evaluatorSettings.PklEvaluatorSettings
+import org.pkl.core.evaluatorSettings.TraceMode
 import org.pkl.core.externalreader.ExternalReaderProcess
 import org.pkl.core.externalreader.ExternalResourceResolver
 import org.pkl.core.externalreader.ModuleReaderSpec
@@ -227,7 +228,7 @@ class Server(private val transport: MessageTransport) : AutoCloseable {
         cacheDir,
         dependencies,
         message.outputFormat,
-        message.traceMode,
+        message.traceMode ?: TraceMode.COMPACT,
       )
     } catch (e: IllegalArgumentException) {
       throw ProtocolException(e.message ?: "Failed to create an evalutor. $e", e)

pkl-server/src/test/kotlin/org/pkl/server/BinaryEvaluatorSnippetTests.kt

@@ -21,6 +21,7 @@ import kotlin.reflect.KClass
 import org.junit.platform.commons.annotation.Testable
 import org.pkl.commons.test.InputOutputTestEngine
 import org.pkl.core.*
+import org.pkl.core.evaluatorSettings.TraceMode
 import org.pkl.core.http.HttpClient
 import org.pkl.core.module.ModuleKeyFactories
 
@@ -56,7 +57,7 @@ class BinaryEvaluatorSnippetTestEngine : InputOutputTestEngine() {
       null,
       null,
       null,
-      null,
+      TraceMode.COMPACT,
     )
 
   private fun String.stripFilePaths() =

pkl-server/src/test/kotlin/org/pkl/server/BinaryEvaluatorTest.kt

@@ -21,6 +21,7 @@ import org.assertj.core.api.Assertions.assertThat
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.assertThrows
 import org.pkl.core.*
+import org.pkl.core.evaluatorSettings.TraceMode
 import org.pkl.core.http.HttpClient
 import org.pkl.core.module.ModuleKeyFactories
 import org.pkl.core.resource.ResourceReaders
@@ -45,7 +46,7 @@ class BinaryEvaluatorTest {
       null,
       null,
       null,
-      null,
+      TraceMode.COMPACT,
     )
 
   private fun evaluate(text: String, expression: String?) =

stdlib/EvaluatorSettings.pkl

@@ -113,11 +113,10 @@ externalResourceReaders: Mapping<String, ExternalReader>?
 ///
 /// Possible values:
 ///
-/// - `"hidden"`: All trace() calls will not be emitted to stderr.
+/// - `"compact"`: All structures passed to trace() will be emitted on a single line.
-/// - `"default"`: All structures passed to trace() will be emitted on a single line.
 /// - `"pretty"`: All structures passed to trace() will be indented and emitted across multiple lines.
 @Since { version = "0.30.0" }
-traceMode: ("hidden"|"default"|"pretty")?
+traceMode: ("compact"|"pretty")?
 
 const local hostnameRegex = Regex(#"https?://([^/?#]*)"#)