diff --git a/AlgebraicDataflowArchitectureModel/src/models/algebra/Symbol.java b/AlgebraicDataflowArchitectureModel/src/models/algebra/Symbol.java
index f4f29ce..8204dea 100644
--- a/AlgebraicDataflowArchitectureModel/src/models/algebra/Symbol.java
+++ b/AlgebraicDataflowArchitectureModel/src/models/algebra/Symbol.java
@@ -4,7 +4,8 @@
 	private String name;
 	private int arity = 0;
 	private Type operatorType = Type.PREFIX;
-	private Symbol inverses[] = null;
+	private Symbol[] inverses = null;
+	private Type[] signature = null;
 	
 	public Symbol(String name) {
 		this.name = name;
@@ -50,6 +51,14 @@
 		this.inverses = inverses;
 	}
 
+	public Type[] getSignature() {
+		return signature;
+	}
+
+	public void setSignature(Type[] signature) {
+		this.signature = signature;
+	}
+
 	public boolean equals(Object another) {
 		if (!(another instanceof Symbol)) return false;
 		return name.equals(((Symbol) another).name) && arity == ((Symbol) another).arity;
diff --git a/AlgebraicDataflowArchitectureModel/src/models/algebra/Type.java b/AlgebraicDataflowArchitectureModel/src/models/algebra/Type.java
new file mode 100644
index 0000000..53e4b2a
--- /dev/null
+++ b/AlgebraicDataflowArchitectureModel/src/models/algebra/Type.java
@@ -0,0 +1,27 @@
+package models.algebra;
+
+public class Type {
+	private String typeName;
+	private String implementastionTypeName;
+	
+	public Type(String typeName, String implementastionTypeName) {
+		this.typeName = typeName;
+		this.implementastionTypeName = implementastionTypeName;
+	}
+
+	public String getTypeName() {
+		return typeName;
+	}
+	
+	public void setTypeName(String typeName) {
+		this.typeName = typeName;
+	}
+	
+	public String getImplementastionTypeName() {
+		return implementastionTypeName;
+	}
+	
+	public void setImplementastionTypeName(String implementastionTypeName) {
+		this.implementastionTypeName = implementastionTypeName;
+	}
+}
diff --git a/AlgebraicDataflowArchitectureModel/src/models/algebra/Variable.java b/AlgebraicDataflowArchitectureModel/src/models/algebra/Variable.java
index 14bda66..935503b 100644
--- a/AlgebraicDataflowArchitectureModel/src/models/algebra/Variable.java
+++ b/AlgebraicDataflowArchitectureModel/src/models/algebra/Variable.java
@@ -4,16 +4,31 @@
 
 public class Variable extends Expression {
 	private String name;
+	private Type type = null;
 	
 	public Variable(String name) {
 		super();
 		this.name = name;
 	}
 
+	public Variable(String name, Type type) {
+		super();
+		this.name = name;
+		this.type = type;
+	}
+
 	public String getName() {
 		return name;
 	}
 	
+	public Type getType() {
+		return type;
+	}
+
+	public void setType(Type type) {
+		this.type = type;
+	}
+
 	@Override
 	public HashMap<Position, Variable> getVariables() {
 		HashMap<Position, Variable> variables = new HashMap<>();
@@ -56,7 +71,7 @@
 	
 	@Override
 	public Object clone() {
-		return new Variable(name);
+		return new Variable(name, type);
 	}
 	
 	public String toString() {
diff --git a/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/DataConstraintModel.java b/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/DataConstraintModel.java
index aaa3d6f..411eb5e 100644
--- a/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/DataConstraintModel.java
+++ b/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/DataConstraintModel.java
@@ -6,6 +6,7 @@
 import java.util.Set;
 
 import models.algebra.Symbol;
+import models.algebra.Type;
 import parser.Parser;
 
 public class DataConstraintModel {
@@ -21,6 +22,10 @@
 	public static final Symbol cons = new Symbol("cons", 2);
 	public static final Symbol head = new Symbol("head", 1);
 	public static final Symbol body = new Symbol("body", 1);
+	public static final Type typeInt = new Type("Int", "int");
+	public static final Type typeFloat = new Type("Float", "float");
+	public static final Type typeDouble = new Type("Double", "double");
+	public static final Type typeList = new Type("List", "List");
 	
 	static {
 		add.setInverses(new Symbol[] {sub, sub});
diff --git a/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/IdentifierTemplate.java b/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/IdentifierTemplate.java
index c30b091..0ea7b6a 100644
--- a/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/IdentifierTemplate.java
+++ b/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/IdentifierTemplate.java
@@ -1,14 +1,23 @@
 package models.dataConstraintModel;
 
+import models.algebra.Type;
+
 public class IdentifierTemplate {
-	String resourceName = null;
-	int numParameters = 0;
+	private String resourceName = null;
+	private Type resourceStateType = null;
+	private int numParameters = 0;
 	
 	public IdentifierTemplate(String resourceName, int numParameters) {
 		this.resourceName = resourceName;
 		this.numParameters =numParameters;
 	}
 
+	public IdentifierTemplate(String resourceName, Type resourceStateType, int numParameters) {
+		this.resourceName = resourceName;
+		this.resourceStateType = resourceStateType;
+		this.numParameters = numParameters;
+	}
+
 	public String getResourceName() {
 		return resourceName;
 	}
@@ -16,4 +25,12 @@
 	public int getNumberOfParameters() {
 		return numParameters;
 	}
+
+	public Type getResourceStateType() {
+		return resourceStateType;
+	}
+
+	public void setResourceStateType(Type resourceStateType) {
+		this.resourceStateType = resourceStateType;
+	}
 }
diff --git a/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/StateTransition.java b/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/StateTransition.java
index 250a560..06ca47b 100644
--- a/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/StateTransition.java
+++ b/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/StateTransition.java
@@ -60,7 +60,16 @@
 			}
 		}
 		
-		Expression nextStateTerm = getNextStateExpression();
+		Expression nextStateTerm = (Expression) getNextStateExpression().clone();
+		for (Variable var: bindings.keySet()) {
+			HashMap<Position, Variable> vars2 = nextStateTerm.getVariables();
+			for (Variable var2: vars2.values()) {
+				if (var.equals(var2) && bindings.get(var).size() == 1) {
+					nextStateTerm = ((Term) nextStateTerm).substitute(var, bindings.get(var).get(0));
+				}
+			}
+		}
+		
 		HashMap<Position, Variable> nextStateVars = nextStateTerm.getVariables();
 		for (Entry<Position, Variable> nextStateVarEnt: nextStateVars.entrySet()) {
 			Variable var = nextStateVarEnt.getValue();
diff --git a/AlgebraicDataflowArchitectureModel/src/tests/UpdateCodeGenerationTest.java b/AlgebraicDataflowArchitectureModel/src/tests/UpdateCodeGenerationTest.java
index 7e60de3..a10c032 100644
--- a/AlgebraicDataflowArchitectureModel/src/tests/UpdateCodeGenerationTest.java
+++ b/AlgebraicDataflowArchitectureModel/src/tests/UpdateCodeGenerationTest.java
@@ -30,21 +30,21 @@
 		// Pre-defined symbols
 		Symbol floor = new Symbol("floor", 1);
 		
-		IdentifierTemplate payment = new IdentifierTemplate("payment", 0);	// an identifier template to specify the payment resource
-		IdentifierTemplate loyalty = new IdentifierTemplate("loyalty", 0);	// an identifier template to specify the loyalty resource
-		IdentifierTemplate history = new IdentifierTemplate("history", 0);	// an identifier template to specify the payment history resource
-		IdentifierTemplate total = new IdentifierTemplate("total", 0);		// an identifier template to specify the total payment resource
+		IdentifierTemplate payment = new IdentifierTemplate("payment", DataConstraintModel.typeInt, 0);	// an identifier template to specify the payment resource
+		IdentifierTemplate loyalty = new IdentifierTemplate("loyalty", DataConstraintModel.typeInt, 0);	// an identifier template to specify the loyalty resource
+		IdentifierTemplate history = new IdentifierTemplate("history", DataConstraintModel.typeList, 0);// an identifier template to specify the payment history resource
+		IdentifierTemplate total = new IdentifierTemplate("total", DataConstraintModel.typeInt, 0);		// an identifier template to specify the total payment resource
 		
 		// fields
-		final Variable fPayment = new Variable("payment");
-		final Variable fLoyalty = new Variable("loyalty");
-		final Variable fHistory = new Variable("history");
-		final Variable fTotal = new Variable("total");
+		final Variable fPayment = new Variable("fPayment", DataConstraintModel.typeInt);
+		final Variable fLoyalty = new Variable("fLoyalty", DataConstraintModel.typeInt);
+		final Variable fHistory = new Variable("fHistory", DataConstraintModel.typeList);
+		final Variable fTotal = new Variable("fTotal", DataConstraintModel.typeInt);
 		// arguments
-		final Variable aPayment = new Variable("payment");
-		final Variable aLoyalty = new Variable("loyalty");
-		final Variable aHistory = new Variable("history");
-		final Variable aTotal = new Variable("total");
+		final Variable aPayment = new Variable("payment", DataConstraintModel.typeInt);
+		final Variable aLoyalty = new Variable("loyalty", DataConstraintModel.typeInt);
+		final Variable aHistory = new Variable("history", DataConstraintModel.typeList);
+		final Variable aTotal = new Variable("total", DataConstraintModel.typeInt);
 		IResourceStateAccessor pushAccessor = new IResourceStateAccessor() {
 			@Override
 			public Expression getCurrentStateAccessorFor(IdentifierTemplate target, IdentifierTemplate from) {
@@ -158,12 +158,12 @@
 					break;
 				}
 			}
-			System.out.println("void update(" + arg + ") {");
+			System.out.println("void update(" + arg.getType().getImplementastionTypeName() + " " + arg + ") {");
 			System.out.println("\t" + fLoyalty + " = " + loyaltyPushUpdate + ";");
 			System.out.println("}");
 			
 			System.out.println("-- PULL --");
-			System.out.println("int " + loyltyGetter + "() {");
+			System.out.println(loyalty.getResourceStateType().getImplementastionTypeName() + " " + loyltyGetter + "() {");
 			System.out.println("\t return " + c1.deriveUpdateExpressionOf(c1_loyalty, pullAccessor) + ";");
 			System.out.println("}");
 		} catch (ParameterizedIdentifierIsFutureWork | ResolvingMultipleDefinitionIsFutureWork | InvalidMessage
@@ -220,12 +220,12 @@
 					break;
 				}
 			}
-			System.out.println("void update(" + arg + ") {");
+			System.out.println("void update(" + arg.getType().getImplementastionTypeName() + " " + arg + ") {");
 			System.out.println("\t" + fHistory + " = " + historyPushUpdate + ";");
 			System.out.println("}");
 			
 			System.out.println("-- PULL --");
-			System.out.println("List " + historyGetter + "() {");
+			System.out.println(history.getResourceStateType().getImplementastionTypeName() + " " + historyGetter + "() {");
 			System.out.println("\t return " + c2.deriveUpdateExpressionOf(c2_history, pullAccessor) + ";");
 			System.out.println("}");
 		} catch (ParameterizedIdentifierIsFutureWork | ResolvingMultipleDefinitionIsFutureWork | InvalidMessage
@@ -282,12 +282,12 @@
 					break;
 				}
 			}
-			System.out.println("void update(" + arg + ") {");
+			System.out.println("void update(" + arg.getType().getImplementastionTypeName() + " " + arg + ") {");
 			System.out.println("\t" + fTotal + " = " + totalPushUpdate + ";");
 			System.out.println("}");
 			
 			System.out.println("-- PULL --");
-			System.out.println("int " + totalGetter + "() {");
+			System.out.println(total.getResourceStateType().getImplementastionTypeName() + " " + totalGetter + "() {");
 			System.out.println("\t return " + c3.deriveUpdateExpressionOf(c3_total, pullAccessor) + ";");
 			System.out.println("}");
 		} catch (ParameterizedIdentifierIsFutureWork | ResolvingMultipleDefinitionIsFutureWork | InvalidMessage