diff --git a/src/main/java/de/dhbwstuttgart/typeinference/unify/UnifyResultListener.java b/src/main/java/de/dhbwstuttgart/typeinference/unify/UnifyResultListener.java
new file mode 100644
index 00000000..f490ccde
--- /dev/null
+++ b/src/main/java/de/dhbwstuttgart/typeinference/unify/UnifyResultListener.java
@@ -0,0 +1,7 @@
+package de.dhbwstuttgart.typeinference.unify;
+
+public interface UnifyResultListener {
+
+	void onNewTypeResultFound(UnifyResultEvent evt);
+
+}
diff --git a/src/main/java/de/dhbwstuttgart/typeinference/unify/model/hashKeyType.java b/src/main/java/de/dhbwstuttgart/typeinference/unify/model/hashKeyType.java
new file mode 100644
index 00000000..dedfcd86
--- /dev/null
+++ b/src/main/java/de/dhbwstuttgart/typeinference/unify/model/hashKeyType.java
@@ -0,0 +1,25 @@
+package de.dhbwstuttgart.typeinference.unify.model;
+
+public class hashKeyType {
+	UnifyType realType;
+	
+	hashKeyType(UnifyType realType) {
+		this.realType= realType;
+	}
+	
+	@Override
+	public boolean equals(Object obj) {
+		if (obj instanceof hashKeyType) {
+			return realType.equals(((hashKeyType)obj).realType);
+		}
+		else
+		{
+			return false;
+		}
+	}
+	
+	@Override
+	public int hashCode() {
+		return realType.hashCode();
+	}
+}