Improve toString for the debugger

Author: koperagen

core/src/main/kotlin/org/jetbrains/kotlinx/dataframe/codeGen/GeneratedField.kt

@@ -5,9 +5,9 @@ import org.jetbrains.kotlinx.dataframe.impl.codeGen.needsQuoting
 import org.jetbrains.kotlinx.dataframe.schema.ColumnSchema
 
 public sealed interface FieldType {
-    public class ValueFieldType(public val typeFqName: String) : FieldType
-    public class FrameFieldType(public val markerName: String, public val nullable: Boolean) : FieldType
-    public class GroupFieldType(public val markerName: String) : FieldType
+    public data class ValueFieldType(public val typeFqName: String) : FieldType
+    public data class FrameFieldType(public val markerName: String, public val nullable: Boolean) : FieldType
+    public data class GroupFieldType(public val markerName: String) : FieldType
 }
 
 /**
@@ -88,6 +88,11 @@ public class ValidFieldName private constructor(private val identifier: String,
         return ValidFieldName(identifier = identifier + other.identifier, needsQuote = needsQuote || other.needsQuote)
     }
 
+    override fun toString(): String {
+        return identifier
+    }
+
+
     public companion object {
         public fun of(name: String): ValidFieldName {
             val needsQuote = name.needsQuoting()

dataframe-openapi/src/main/kotlin/org/jetbrains/kotlinx/dataframe/io/OpenApiMarker.kt

@@ -40,7 +40,7 @@ internal sealed class OpenApiMarker private constructor(
     abstract fun toFieldType(): FieldType
 
     override fun toString(): String =
-        "MyMarker(markerType = ${this::class}, name = $name, isOpen = $isOpen, fields = $fields, superMarkers = $superMarkers, visibility = $visibility, typeParameters = $typeParameters, typeArguments = $typeArguments)"
+        "MyMarker(name = $name, isOpen = $isOpen, markerType = ${this::class}, fields = $fields, superMarkers = $superMarkers, visibility = $visibility, typeParameters = $typeParameters, typeArguments = $typeArguments)"
 
     /**
      * A [Marker] that will be used to generate an enum.