diff --git a/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/DataConstraintModel.java b/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/DataConstraintModel.java
index 1507ea3..3bdb1dd 100644
--- a/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/DataConstraintModel.java
+++ b/AlgebraicDataflowArchitectureModel/src/models/dataConstraintModel/DataConstraintModel.java
@@ -1,9 +1,13 @@
 package models.dataConstraintModel;
 
+import java.util.AbstractMap;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
+import java.util.Stack;
 
 import models.algebra.Constant;
 import models.algebra.Expression;
@@ -201,8 +205,7 @@
 				return children[0] + ".equals(" + children[1] + ")";
 			}
 			return "(" + children[0] + "==" + children[1] + ")";
-		}
-		
+		}		
 	}, new Symbol.ICalculator() {
 		@Override
 		public Expression calculate(List<Expression> args) {
@@ -246,7 +249,6 @@
 			}
 			return "(" + children[0] + "!=" + children[1] + ")";
 		}
-		
 	}, new Symbol.ICalculator() {
 		@Override
 		public Expression calculate(List<Expression> args) {
@@ -467,13 +469,89 @@
 		}
 	});
 	public static final Symbol cons = new Symbol("cons", 2, Symbol.Type.PREFIX, "($x,$y)->$x.add(0, $y)", Symbol.Type.LAMBDA_WITH_SIDE_EFFECT, new int[] {1, 0});
-	public static final Symbol append = new Symbol("append", 2, Symbol.Type.PREFIX, "add", Symbol.Type.METHOD_WITH_SIDE_EFFECT);
-	public static final Symbol remove = new Symbol("remove", 2, Symbol.Type.PREFIX, "remove", Symbol.Type.METHOD_WITH_SIDE_EFFECT);
+	public static final Symbol append = new Symbol("append", 2, Symbol.Type.PREFIX, "add", Symbol.Type.METHOD_WITH_SIDE_EFFECT);		// Don't calculate here (Calculated in simulator).
+	public static final Symbol remove = new Symbol("remove", 2, Symbol.Type.PREFIX, "remove", Symbol.Type.METHOD_WITH_SIDE_EFFECT);		// Don't calculate here (Calculated in simulator).
 	public static final Symbol head = new Symbol("head", 1, Symbol.Type.PREFIX, "($x)->$x.get(0)", Symbol.Type.LAMBDA);
 	public static final Symbol tail = new Symbol("tail", 1, Symbol.Type.PREFIX, "($x)->$x.subList(1, $x.size())", Symbol.Type.LAMBDA);
-	public static final Symbol length = new Symbol("length", 1, Symbol.Type.PREFIX, "($x)->$x.size()", Symbol.Type.LAMBDA);
-	public static final Symbol get = new Symbol("get", 2, Symbol.Type.PREFIX, "get", Symbol.Type.METHOD);
-	public static final Symbol set = new Symbol("set", 3, Symbol.Type.PREFIX, "set", Symbol.Type.METHOD_WITH_SIDE_EFFECT);
+	public static final Symbol length = new Symbol("length", 1, Symbol.Type.PREFIX, "($x)->$x.size()", Symbol.Type.LAMBDA, new Symbol.ICalculator() {
+		@Override
+		public Expression calculate(List<Expression> args) {
+			if (args.get(0).getClass() == Constant.class && ((Constant) args.get(0)).getSymbol().equals(nil)) {
+				return new Constant("0", typeInt);
+			}
+			if (args.get(0) instanceof Term) {
+				Term term = (Term) args.get(0);
+				Type type = term.getType();
+				if (typeList.isAncestorOf(type)) {
+					int len = 0;
+					while (term.getSymbol().equals(DataConstraintModel.append)) {
+						len++;
+						term = (Term) term.getChild(0);
+					}
+					if (term instanceof ListTerm) {
+						len += ((ListTerm) term).getChildren().size();
+						return new Constant(Integer.toString(len), typeInt);
+					}
+				} else if (typeMap.isAncestorOf(type)) {
+					HashSet<String> keySet = new HashSet<>();
+					while (term.getSymbol().equals(DataConstraintModel.insert)) {
+						if (term.getChild(1).getClass() == Constant.class) {
+							keySet.add((String) ((Constant) term.getChild(1)).getValue());
+						}
+						term = (Term) term.getChild(0);
+					}
+					if (term instanceof MapTerm) {
+						keySet.addAll(((MapTerm) term).keySet());
+						return new Constant(Integer.toString(keySet.size()), typeInt);
+					}
+				} else if (typeJson.isAncestorOf(type)) {
+					HashSet<String> keySet = new HashSet<>();
+					while (term.getSymbol().equals(DataConstraintModel.addMember)) {
+						if (term.getChild(1).getClass() == Constant.class) {
+							keySet.add((String) ((Constant) term.getChild(1)).getValue());
+						}
+						term = (Term) term.getChild(0);
+					}
+					if (term instanceof JsonTerm) {
+						keySet.addAll(((JsonTerm) term).keySet());
+						return new Constant(Integer.toString(keySet.size()), typeInt);
+					}
+				}
+			}
+			return null;
+		}
+	});
+	public static final Symbol get = new Symbol("get", 2, Symbol.Type.PREFIX, "get", Symbol.Type.METHOD, new Symbol.ICalculator() {
+		@Override
+		public Expression calculate(List<Expression> args) {
+			if (args.get(1).getClass() == Constant.class && ((Constant) args.get(1)).getType().equals(typeInt)) {
+				int idx = Integer.parseInt(((Constant) args.get(1)).toString());
+				if (args.get(0) instanceof Term) {
+					Term term = (Term) args.get(0);
+					Type type = term.getType();
+					if (typeList.isAncestorOf(type)) {
+						Stack<Expression> appendedChldren = new Stack<>();
+						while (term.getSymbol().equals(DataConstraintModel.append)) {
+							if (!(term.getChild(0) instanceof Term)) {
+								return null;
+							}
+							appendedChldren.push(term.getChild(1));
+							term = (Term) term.getChild(0);
+						}
+						if (term instanceof ListTerm) {
+							ListTerm listTerm = (ListTerm) term.clone();
+							for (Expression child: appendedChldren) {
+								listTerm.append(child);
+							}
+							return listTerm.get(idx);
+						}
+					}
+				}
+			}
+			return null;
+		}
+	});
+	public static final Symbol set = new Symbol("set", 3, Symbol.Type.PREFIX, "set", Symbol.Type.METHOD_WITH_SIDE_EFFECT);				// Don't calculate here (Calculated in simulator).
 	public static final Symbol contains = new Symbol("contains", 2, Symbol.Type.PREFIX, new Symbol.IImplGenerator() {
 		@Override
 		public String generate(Type type, Type[] childrenTypes, String[] childrenImpl, String[] childrenSideEffects, String[] sideEffect) {
@@ -561,6 +639,42 @@
 			return null;
 		}
 	});
+	public static final Symbol indexOf = new Symbol("indexOf", 2, Symbol.Type.PREFIX, "indexOf", Symbol.Type.METHOD, new Symbol.ICalculator() {
+		@Override
+		public Expression calculate(List<Expression> args) {
+			if (args.get(0) instanceof Term) {
+				Term term = (Term) args.get(0);
+				Type type = term.getType();
+				if (typeList.isAncestorOf(type)) {
+					Stack<Expression> appendedChldren = new Stack<>();
+					while (term.getSymbol().equals(DataConstraintModel.append)) {
+						if (!(term.getChild(0) instanceof Term)) {
+							return null;
+						}
+						appendedChldren.push(term.getChild(1));
+						term = (Term) term.getChild(0);
+					}
+					if (term instanceof ListTerm) {
+						int idx = 0;
+						ListTerm listTerm = (ListTerm) term;
+						for (Expression child: listTerm.getChildren()) {
+							if (child.equals(args.get(1))) {
+								return new Constant(Integer.toString(idx), typeInt);
+							}
+							idx++;
+						}
+						for (Expression child: appendedChldren) {
+							if (child.equals(args.get(1))) {
+								return new Constant(Integer.toString(idx), typeInt);
+							}
+							idx++;
+						}
+					}
+				}
+			}
+			return null;
+		}
+	});
 	public static final Symbol nil = new Symbol("nil", 0, Symbol.Type.PREFIX, new Symbol.IImplGenerator() {
 		@Override
 		public String generate(Type type, Type[] childrenTypes, String[] children, String[] childrenSideEffects, String[] sideEffect) {
@@ -650,26 +764,39 @@
 	public static final Symbol snd = new Symbol("snd", 1, Symbol.Type.PREFIX, "getValue", Symbol.Type.METHOD);
 	public static final Symbol left = new Symbol("left", 1, Symbol.Type.PREFIX, "getLeft", Symbol.Type.METHOD);
 	public static final Symbol right = new Symbol("right", 1, Symbol.Type.PREFIX, "getRight", Symbol.Type.METHOD);
-	public static final Symbol insert = new Symbol("insert", 3, Symbol.Type.PREFIX, "put", Symbol.Type.METHOD_WITH_SIDE_EFFECT);
-	public static final Symbol delete = new Symbol("delete", 2, Symbol.Type.PREFIX, "remove", Symbol.Type.METHOD_WITH_SIDE_EFFECT);
-	public static final Symbol lookup = new Symbol("lookup", 2, Symbol.Type.PREFIX, "get", Symbol.Type.METHOD);
-//	public static final Symbol lookup = new Symbol("lookup", 2, Symbol.Type.PREFIX, new Symbol.IImplGenerator() {
-//		final int count[] = {0};
-//		@Override
-//		public String generate(Type type, String[] childrenImpl, String[] childrenSideEffects, String[] sideEffect) {
-//			String temp = "temp_get" + count[0];
-//			String impl = childrenSideEffects[0] + childrenSideEffects[1];
-//			impl += type.getInterfaceTypeName() + " " + temp + ";\n";
-//			impl += "if (" + childrenImpl[0] + ".get(" + childrenImpl[1] + ") != null) {\n";
-//			impl += "\t" + temp + " = " + childrenImpl[0] + ".get(" + childrenImpl[1] + ");\n";
-//			impl += "} else {\n";
-//			impl += "\t" + temp + " = " + getDefaultValue(type) + ";\n";
-//			impl += "}";
-//			sideEffect[0] = impl;
-//			count[0]++;
-//			return temp;
-//		}
-//	});
+	public static final Symbol insert = new Symbol("insert", 3, Symbol.Type.PREFIX, "put", Symbol.Type.METHOD_WITH_SIDE_EFFECT);		// Don't calculate here (Calculated in simulator).
+	public static final Symbol delete = new Symbol("delete", 2, Symbol.Type.PREFIX, "remove", Symbol.Type.METHOD_WITH_SIDE_EFFECT);		// Don't calculate here (Calculated in simulator).
+	public static final Symbol lookup = new Symbol("lookup", 2, Symbol.Type.PREFIX, "get", Symbol.Type.METHOD, new Symbol.ICalculator() {
+		@Override
+		public Expression calculate(List<Expression> args) {
+			if (args.get(1).getClass() == Constant.class && ((Constant) args.get(1)).getType().equals(typeString)) {
+				String key = (String) ((Constant) args.get(1)).getValue();
+				if (args.get(0) instanceof Term) {
+					Term term = (Term) args.get(0);
+					Type type = term.getType();
+					if (typeMap.isAncestorOf(type)) {
+						Stack<Map.Entry<Expression, Expression>> appendedChldren = new Stack<>();
+						while (term.getSymbol().equals(DataConstraintModel.insert)) {
+							if (!(term.getChild(0) instanceof Term)) {
+								return null;
+							}
+							appendedChldren.push(new AbstractMap.SimpleEntry<>(term.getChild(0), term.getChild(1)));
+							term = (Term) term.getChild(0);
+						}
+						if (term instanceof MapTerm) {
+							MapTerm mapTerm = (MapTerm) term.clone();
+							for (Map.Entry<Expression, Expression> childEnt: appendedChldren) {
+								if (childEnt.getKey().getClass() == Constant.class)
+								mapTerm.insert((String) ((Constant) childEnt.getKey()).getValue(), childEnt.getValue());
+							}
+							return mapTerm.get(key);
+						}
+					}
+				}
+			}
+			return null;
+		}
+	});
 	public static final Symbol addMember = new Symbol("addMember", 3, Symbol.Type.PREFIX, "put", Symbol.Type.METHOD_WITH_SIDE_EFFECT);
 	public static final Symbol dot = new Symbol(Parser.DOT, 2, Symbol.Type.INFIX, "get", Symbol.Type.METHOD);
 	public static final Symbol dotParam = new Symbol(Parser.DOT, 2, Symbol.Type.INFIX, "get", Symbol.Type.METHOD);
@@ -710,6 +837,7 @@
 		head.setSignature(new Type[] {null, typeList});
 		tail.setSignature(new Type[] {typeList, typeList});
 		contains.setSignature(new Type[] {typeBoolean, null, null});
+		indexOf.setSignature(new Type[] {typeInt, typeList, null});
 		length.setSignature(new Type[] {typeInt, null});
 		get.setSignature(new Type[] {null, typeList, typeInt});
 		set.setSignature(new Type[] {typeList, typeList, typeInt, null});
@@ -792,6 +920,7 @@
 		addSymbol(tail);
 		addSymbol(length);
 		addSymbol(contains);
+		addSymbol(indexOf);
 		addSymbol(get);
 		addSymbol(set);
 		addSymbol(cond);