diff --git a/AlgebraicDataflowArchitectureModel/models/Twitter.model b/AlgebraicDataflowArchitectureModel/models/Twitter.model
index 98d391b..f02f134 100644
--- a/AlgebraicDataflowArchitectureModel/models/Twitter.model
+++ b/AlgebraicDataflowArchitectureModel/models/Twitter.model
@@ -1,53 +1,53 @@
 channel a_Tweet {
-	out a_user_timeline(l:List, a_tweet(t:Str)) == cons(t, l)
-	out a_user_timeline(l, e) == l
+	out a_tweets(l:List, a_tweet(t:Str, time:Long)) == cons(tuple(time, t), l)
+	out a_tweets(l, e) == l
 }
 
 channel a_Follow {
-	out a_follows(f:List, a_follow(u:Int)) == cons(u, f)
-	out a_follows(f, e) == f
+	out a_following(f:List, a_follow(u:Int)) == cons(u, f)
+	out a_following(f, e) == f
 }
 
 channel a_Home {
-	in a_user_timeline(la1, update_a(f2, la2, lb2, lc2)) == la2
-	in b_user_timeline(lb1, update_a(f2, la2, lb2, lc2)) == lb2
-	in c_user_timeline(lc1, update_a(f2, la2, lb2, lc2)) == lc2
-	in a_follows(f, update_a(f2, la2, lb2, lc2)) == f2
-	out a_home_timeline(t:List, update_a(f2, la2, lb2, lc2)) == merge(la2, if(contains(f2,2), merge(lb2, if(contains(f2,3), lc2, nil)), if(contains(f2,3), lc2, nil)))
+	in a_tweets(la1, update_a(f2, la2, lb2, lc2)) == la2
+	in b_tweets(lb1, update_a(f2, la2, lb2, lc2)) == lb2
+	in c_tweets(lc1, update_a(f2, la2, lb2, lc2)) == lc2
+	in a_following(f, update_a(f2, la2, lb2, lc2)) == f2
+	out a_timeline(t:List, update_a(f2, la2, lb2, lc2)) == merge(la2, if(contains(f2,2), merge(lb2, if(contains(f2,3), lc2, nil)), if(contains(f2,3), lc2, nil)))
 }
 
 channel b_Tweet {
-	out b_user_timeline(l:List, b_tweet(t:Str)) == cons(t, l)
-	out b_user_timeline(l, e) == l
+	out b_tweets(l:List, b_tweet(t:Str, time:Long)) == cons(tuple(time, t), l)
+	out b_tweets(l, e) == l
 }
 
 channel b_Follow {
-	out b_follows(f:List, b_follow(u:Int)) == cons(u, f)
-	out b_follows(f, e) == f
+	out b_following(f:List, b_follow(u:Int)) == cons(u, f)
+	out b_following(f, e) == f
 }
 
 channel b_Home {
-	in a_user_timeline(la1, update_b(f2, la2, lb2, lc2)) == la2
-	in b_user_timeline(lb1, update_b(f2, la2, lb2, lc2)) == lb2
-	in c_user_timeline(lc1, update_b(f2, la2, lb2, lc2)) == lc2
-	in b_follows(f, update_b(f2, la2, lb2, lc2)) == f2
-	out b_home_timeline(t:List, update_b(f2, la2, lb2, lc2)) == merge(lb2, if(contains(f2,1), merge(la2, if(contains(f2,3), lc2, nil)), if(contains(f2,3), lc2, nil)))
+	in a_tweets(la1, update_b(f2, la2, lb2, lc2)) == la2
+	in b_tweets(lb1, update_b(f2, la2, lb2, lc2)) == lb2
+	in c_tweets(lc1, update_b(f2, la2, lb2, lc2)) == lc2
+	in b_following(f, update_b(f2, la2, lb2, lc2)) == f2
+	out b_timeline(t:List, update_b(f2, la2, lb2, lc2)) == merge(lb2, if(contains(f2,1), merge(la2, if(contains(f2,3), lc2, nil)), if(contains(f2,3), lc2, nil)))
 }
 
 channel c_Tweet {
-	out c_user_timeline(l:List, c_tweet(t:Str)) == cons(t, l)
-	out c_user_timeline(l, e) == l
+	out c_tweets(l:List, c_tweet(t:Str, time:Long)) == cons(tuple(time, t), l)
+	out c_tweets(l, e) == l
 }
 
 channel c_Follow {
-	out c_follows(f:List, c_follow(u:Int)) == cons(u, f)
-	out c_follows(f, e) == f
+	out c_following(f:List, c_follow(u:Int)) == cons(u, f)
+	out c_following(f, e) == f
 }
 
 channel c_Home {
-	in a_user_timeline(la1, update_c(f2, la2, lb2, lc2)) == la2
-	in b_user_timeline(lb1, update_c(f2, la2, lb2, lc2)) == lb2
-	in c_user_timeline(lc1, update_c(f2, la2, lb2, lc2)) == lc2
-	in c_follows(f, update_c(f2, la2, lb2, lc2)) == f2
-	out c_home_timeline(t:List, update_c(f2, la2, lb2, lc2)) == merge(lc2, if(contains(f2,1), merge(la2, if(contains(f2,2), lb2, nil)), if(contains(f2,2), lb2, nil)))
+	in a_tweets(la1, update_c(f2, la2, lb2, lc2)) == la2
+	in b_tweets(lb1, update_c(f2, la2, lb2, lc2)) == lb2
+	in c_tweets(lc1, update_c(f2, la2, lb2, lc2)) == lc2
+	in c_following(f, update_c(f2, la2, lb2, lc2)) == f2
+	out c_timeline(t:List, update_c(f2, la2, lb2, lc2)) == merge(lc2, if(contains(f2,1), merge(la2, if(contains(f2,2), lb2, nil)), if(contains(f2,2), lb2, nil)))
 }
diff --git a/AlgebraicDataflowArchitectureModel/src/algorithms/JavaMethodBodyGenerator.java b/AlgebraicDataflowArchitectureModel/src/algorithms/JavaMethodBodyGenerator.java
index d061f00..00df97c 100644
--- a/AlgebraicDataflowArchitectureModel/src/algorithms/JavaMethodBodyGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/algorithms/JavaMethodBodyGenerator.java
@@ -22,6 +22,7 @@
 import models.algebra.Variable;
 import models.dataConstraintModel.ChannelGenerator;
 import models.dataConstraintModel.ChannelMember;
+import models.dataConstraintModel.DataConstraintModel;
 import models.dataConstraintModel.IdentifierTemplate;
 import models.dataFlowModel.DataFlowModel;
 import models.dataFlowModel.DataflowChannelGenerator;
@@ -68,6 +69,7 @@
 				}
 			});
 			sum.setImplOperatorType(Symbol.Type.GENERATIVE);
+			sum.setSignature(new Type[] {DataConstraintModel.typeInt, DataConstraintModel.typeList});
 //			sum.setImplName("stream().mapToInt(x->x).sum");
 //			sum.setImplOperatorType(Symbol.Type.METHOD);
 		}
@@ -91,7 +93,7 @@
 						}
 					}
 					String idxGetter = "";
-					if (compType.startsWith("AbstractMap.SimpleEntry")) {
+					if (compType.startsWith("Map.Entry")) {
 						idxGetter = ".getKey()";
 					}
 					count[0]++;
@@ -121,6 +123,7 @@
 				}
 			});
 			merge.setImplOperatorType(Symbol.Type.GENERATIVE);
+			merge.setSignature(new Type[] {DataConstraintModel.typeList, DataConstraintModel.typeList, DataConstraintModel.typeList});
 		}
 
 		// Create a map from type names (lower case) to their types.
diff --git a/AlgebraicDataflowArchitectureModel/src/algorithms/JerseyMethodBodyGenerator.java b/AlgebraicDataflowArchitectureModel/src/algorithms/JerseyMethodBodyGenerator.java
index ee6d6de..d0f5f6b 100644
--- a/AlgebraicDataflowArchitectureModel/src/algorithms/JerseyMethodBodyGenerator.java
+++ b/AlgebraicDataflowArchitectureModel/src/algorithms/JerseyMethodBodyGenerator.java
@@ -24,6 +24,7 @@
 import models.algebra.ValueUndefined;
 import models.dataConstraintModel.ChannelGenerator;
 import models.dataConstraintModel.ChannelMember;
+import models.dataConstraintModel.DataConstraintModel;
 import models.dataFlowModel.DataFlowModel;
 import models.dataFlowModel.DataflowChannelGenerator;
 import models.dataFlowModel.PushPullAttribute;
@@ -70,6 +71,7 @@
 				}
 			});
 			sum.setImplOperatorType(Symbol.Type.GENERATIVE);
+			sum.setSignature(new Type[] {DataConstraintModel.typeInt, DataConstraintModel.typeList});
 //			sum.setImplName("stream().mapToInt(x->x).sum");
 //			sum.setImplOperatorType(Symbol.Type.METHOD);
 		}
@@ -123,6 +125,7 @@
 				}
 			});
 			merge.setImplOperatorType(Symbol.Type.GENERATIVE);
+			merge.setSignature(new Type[] {DataConstraintModel.typeList, DataConstraintModel.typeList, DataConstraintModel.typeList});
 		}
 
 		// Create a map from type names (lower case) to their types.
diff --git a/AlgebraicDataflowArchitectureModel/src/algorithms/TypeInference.java b/AlgebraicDataflowArchitectureModel/src/algorithms/TypeInference.java
index c831849..7b37323 100644
--- a/AlgebraicDataflowArchitectureModel/src/algorithms/TypeInference.java
+++ b/AlgebraicDataflowArchitectureModel/src/algorithms/TypeInference.java
@@ -13,6 +13,7 @@
 import models.Node;
 import models.algebra.Expression;
 import models.algebra.Position;
+import models.algebra.Symbol;
 import models.algebra.Term;
 import models.algebra.Type;
 import models.algebra.Variable;
@@ -270,14 +271,31 @@
 					terms.addAll(subTerms.values());
 				}
 				for (Term t: terms) {
-					if (t.getSymbol().equals(DataConstraintModel.cons)) {
+					Symbol symbol = t.getSymbol();
+					if (symbol.equals(DataConstraintModel.cons) || (symbol.getSignature() != null && symbol.getSignature()[0] == DataConstraintModel.typeList)) {
 						// If the root symbol of the term is cons.
 						List<Expression> consExps = new ArrayList<>();
 						consExps.add(t);
 						expToCons.put(System.identityHashCode(t), consExps);
-						for (Expression e: t.getChildren()) {
-							consExps.add(e);
-							expToCons.put(System.identityHashCode(e), consExps);
+						if (symbol.equals(DataConstraintModel.cons)) {
+							for (Expression e: t.getChildren()) {
+								consExps.add(e);
+								expToCons.put(System.identityHashCode(e), consExps);
+							}
+						} else {
+							consExps.add(null);				// consExps.get(1)
+							for (int i = 1; i < symbol.getSignature().length; i++) {
+								Type tc = symbol.getSignature()[i];
+								if (tc == DataConstraintModel.typeList) {
+									Expression e = t.getChildren().get(i - 1);
+									consExps.add(e);		// consExps.get(2)
+									expToCons.put(System.identityHashCode(e), consExps);
+									break;
+								}
+							}
+							if (consExps.size() < 2) {
+								consExps.add(null);
+							}
 						}
 						Type newType = getExpTypeIfUpdatable(t.getType(), consExps.get(2));
 						if (newType != null) {
@@ -325,7 +343,7 @@
 							}
 						}
 						cons.put(System.identityHashCode(consExps), t.getType());
-					} else if (t.getSymbol().equals(DataConstraintModel.tuple)) {
+					} else if (symbol.equals(DataConstraintModel.tuple)) {
 						// If the root symbol of the term is tuple.
 						List<Expression> tupleExps = new ArrayList<>();
 						List<Type> argsTypeList = new ArrayList<>();
@@ -528,10 +546,10 @@
 					updateExps.put(System.identityHashCode(consComponents.get(2)), consComponents.get(2));
 				}
 				Type compType = listComponentTypes.get(expType);
-				if (consComponents.get(1) instanceof Variable) {
+				if (consComponents.get(1) != null && consComponents.get(1) instanceof Variable) {
 					((Variable) consComponents.get(1)).setType(compType);
 					updateExps.put(System.identityHashCode(consComponents.get(1)), consComponents.get(1));
-				} else if (consComponents.get(1) instanceof Term) {
+				} else if (consComponents.get(1) != null && consComponents.get(1) instanceof Term) {
 					((Term) consComponents.get(1)).setType(compType);
 					updateExps.put(System.identityHashCode(consComponents.get(1)), consComponents.get(1));
 				}
@@ -573,10 +591,10 @@
 					updateExps.put(System.identityHashCode(consComponents.get(0)), consComponents.get(0));
 				}
 				compType = listComponentTypes.get(expType);
-				if (consComponents.get(1) instanceof Variable) {
+				if (consComponents.get(1) != null && consComponents.get(1) instanceof Variable) {
 					((Variable) consComponents.get(1)).setType(compType);
 					updateExps.put(System.identityHashCode(consComponents.get(1)), consComponents.get(1));
-				} else if (consComponents.get(1) instanceof Term) {
+				} else if (consComponents.get(1) != null && consComponents.get(1) instanceof Term) {
 					((Term) consComponents.get(1)).setType(compType);
 					updateExps.put(System.identityHashCode(consComponents.get(1)), consComponents.get(1));
 				}