added proper alias checks to the match implementations of parametrized types

src/main/java/io/usethesource/vallang/type/AbstractDataType.java

@@ -428,7 +428,7 @@ public boolean match(Type matched, Map<Type, Type> bindings) throws FactTypeUseE
             return false;
         }
 
-        if (matched.isAbstractData() || matched.isBottom()) {
+        if (matched.isAbstractData() || (matched.isAliased() && matched.getAliased().isAbstractData()) || matched.isBottom()) {
             return getTypeParameters().match(matched.getTypeParameters(), bindings);
         }
 

src/main/java/io/usethesource/vallang/type/ListType.java

@@ -286,12 +286,11 @@ protected Type glbWithList(Type type) {
 	}
 
 	@Override
-	public boolean match(Type matched, Map<Type, Type> bindings)
-			throws FactTypeUseException {
+	public boolean match(Type matched, Map<Type, Type> bindings) throws FactTypeUseException {
 		if (!super.match(matched, bindings)) {
 			return false;
 		}
-		else if (matched.isList() || matched.isBottom()) {
+		else if (matched.isList() || (matched.isAliased() && matched.getAliased().isList()) || matched.isBottom()) {
 			return getElementType().match(matched.getElementType(), bindings);
 		}
 

src/main/java/io/usethesource/vallang/type/MapType.java

@@ -244,7 +244,7 @@ public boolean match(Type matched, Map<Type, Type> bindings)throws FactTypeUseEx
           return false;
         }
 
-        if (matched.isMap() || matched.isBottom()) {
+        if (matched.isMap() || (matched.isAliased() && matched.getAliased().isMap()) ||  matched.isBottom()) {
 				  return getKeyType().match(matched.getKeyType(), bindings)
           && getValueType().match(matched.getValueType(), bindings);
         }

src/main/java/io/usethesource/vallang/type/SetType.java

@@ -289,7 +289,7 @@ public boolean match(Type matched, Map<Type, Type> bindings) throws FactTypeUseE
 		if (!super.match(matched, bindings)) {
 			return false;
 		}
-		else if (matched.isSet() || matched.isBottom()) {
+		else if (matched.isSet() || (matched.isAliased() && matched.getAliased().isSet()) || matched.isBottom()) {
 			return getElementType().match(matched.getElementType(), bindings);
 		}
 

src/main/java/io/usethesource/vallang/type/TupleType.java

@@ -419,7 +419,7 @@ public boolean match(Type matched, Map<Type, Type> bindings)
             return false;
         }
 
-        if (matched.isTuple() || matched.isBottom()) {
+        if (matched.isTuple() || (matched.isAliased() && matched.getAliased().isTuple()) || matched.isBottom()) {
             for (int i = getArity() - 1; i >= 0; i--) {
                 if (!getFieldType(i).match(matched.getFieldType(i), bindings)) {
                     return false;

src/test/java/io/usethesource/vallang/specification/TypeTest.java

@@ -10,6 +10,7 @@
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Map.Entry;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
@@ -168,21 +169,35 @@ public void testParameterizedAlias(TypeFactory ft, TypeStore ts) {
         Type T = ft.parameterType("T");
         // DiGraph[&T] = rel[&T from ,&T to]
         @SuppressWarnings("deprecation")
-        Type DiGraph = ft.aliasType(ts, "DiGraph", ft.relType(T, "from", T, "to"), T);
+        Type relType = ft.relType(T, "from", T, "to");
+        Type DiGraph = ft.aliasType(ts, "DiGraph", relType, T);
         Type IntInstance = ft.relType(ft.integerType(), ft.integerType());
         Type ValueInstance = ft.relType(ft.valueType(), ft.valueType());
 
-       // after instantiation rel[int,int] is a sub-type of rel[&T, &T]
+       // after instantiation rel[int,int] is a sub-type of rel[&T, &T], and vice versa, and also reflectively
         assertTrue(IntInstance.isSubtypeOf(DiGraph));
-
+        assertTrue(DiGraph.isSubtypeOf(IntInstance));
+        assertTrue(DiGraph.isSubtypeOf(DiGraph));
+
+        // vice versa: the aliased type can be matched using the alias type
+        Map<Type, Type> bindings = new HashMap<>();
+        assertTrue(DiGraph.match(IntInstance, bindings));
+        assertTrue(bindings.get(T) == ft.integerType());
+
+        // and the alias type can be matched by the aliased type (not we reuse the bindings from the previous assert)
+        Type instanceDiGraph = DiGraph.instantiate(bindings);
+        bindings = new HashMap<>(); // reset the bindings
+        assertTrue(relType.match(instanceDiGraph, bindings));
+        assertTrue(bindings.get(T) == ft.integerType());
+
         // before instantiation, the parameterized type rel[&T, &T] 
         // could be instantiated later by rel[int, int]
         assertTrue(DiGraph.isSubtypeOf(IntInstance));
 
         // the generic graph is also always a sub-type of the most general instantiation
         assertTrue(DiGraph.isSubtypeOf(ValueInstance));
 
-        Map<Type, Type> bindings = new HashMap<>();
+        bindings = new HashMap<>();
         DiGraph.match(IntInstance, bindings);
         assertTrue(bindings.get(T) == ft.integerType());