--- a/truffle/com.oracle.truffle.object/src/com/oracle/truffle/object/Transition.java	Fri Nov 13 15:36:25 2015 +0100
+++ b/truffle/com.oracle.truffle.object/src/com/oracle/truffle/object/Transition.java	Fri Nov 13 16:25:04 2015 +0100
@@ -22,9 +22,10 @@
  */
 package com.oracle.truffle.object;
 
+import java.util.Objects;
+
 import com.oracle.truffle.api.object.ObjectType;
 import com.oracle.truffle.api.object.Property;
-import java.util.Objects;
 
 public abstract class Transition {
     @Override
@@ -90,6 +91,11 @@
         public boolean isDirect() {
             return true;
         }
+
+        @Override
+        public String toString() {
+            return String.format("add(%s)", getProperty());
+        }
     }
 
     public static final class RemovePropertyTransition extends PropertyTransition {
@@ -101,6 +107,11 @@
         public boolean isDirect() {
             return false;
         }
+
+        @Override
+        public String toString() {
+            return String.format("remove(%s)", getProperty());
+        }
     }
 
     public static final class ObjectTypeTransition extends Transition {
@@ -131,6 +142,11 @@
         public boolean isDirect() {
             return true;
         }
+
+        @Override
+        public String toString() {
+            return String.format("objectType(%s)", getObjectType());
+        }
     }
 
     public abstract static class AbstractReplacePropertyTransition extends PropertyTransition {
@@ -161,6 +177,11 @@
             result = prime * result + after.hashCode();
             return result;
         }
+
+        @Override
+        public String toString() {
+            return String.format("replace(%s,%s)", getPropertyBefore(), getPropertyAfter());
+        }
     }
 
     public static final class IndirectReplacePropertyTransition extends AbstractReplacePropertyTransition {