Don't use properties through the element values

src/main/java/com/bio4j/angulillos/AnyEdgeType.java

@@ -0,0 +1,98 @@
+package com.bio4j.angulillos;
+
+/*
+  ## Edges
+
+  A typed edge with explicit source and target.
+
+  - `S` the source TypedVertex, `ST` the source TypedVertex type
+  - `E` the edge, `ET` the edge type
+  - `T` the target TypedVertex, `TT` the target TypedVertex type
+*/
+public interface AnyEdgeType extends
+  AnyElementType,
+  HasFromArity,
+  HasToArity
+{
+
+  AnyVertexType sourceType();
+  AnyVertexType targetType();
+}
+
+// TODO: make it public
+interface TypedEdge <
+  // source vertex
+  S  extends      TypedVertex<S,ST, ?,RV,RE>,
+  ST extends TypedVertex.Type<S,ST, ?,RV,RE>,
+  // edge
+  E  extends      TypedEdge<S,ST, E,ET, T,TT, G,RV,RE>,
+  ET extends TypedEdge.Type<S,ST, E,ET, T,TT, G,RV,RE>,
+  // target vertex
+  T  extends      TypedVertex<T,TT, ?,RV,RE>,
+  TT extends TypedVertex.Type<T,TT, ?,RV,RE>,
+  // graph & raws
+  G extends TypedGraph<G,RV,RE>,
+  RV,RE
+>
+  extends TypedElement<E,ET,G,RE>
+{
+
+  interface Type <
+    // source vertex
+    S  extends      TypedVertex<S,ST, ?,RV,RE>,
+    ST extends TypedVertex.Type<S,ST, ?,RV,RE>,
+    // edge
+    E  extends      TypedEdge<S,ST, E,ET, T,TT, G,RV,RE>,
+    ET extends TypedEdge.Type<S,ST, E,ET, T,TT, G,RV,RE>,
+    // target vertex
+    T  extends      TypedVertex<T,TT, ?,RV,RE>,
+    TT extends TypedVertex.Type<T,TT, ?,RV,RE>,
+    // graph & raws
+    G extends TypedGraph<G,RV,RE>,
+    RV,RE
+  > extends
+    TypedElement.Type<E,ET,G,RE>,
+    AnyEdgeType
+  {
+    ST sourceType();
+    TT targetType();
+
+    /* adds an edge; note that this method does not set any properties. As it needs to be called by vertices in possibly different graphs, all the graph bounds are free with respect to G. */
+    default E addEdge(S from, T to) {
+
+      return this.fromRaw(
+        graph().raw().addEdge( from.raw(), this, to.raw() )
+      );
+    }
+
+  }
+
+
+  /* the source vertex of this edge */
+  default S source() {
+    return type().sourceType().fromRaw(
+      graph().raw().source( raw() )
+    );
+  }
+
+  /* the target vertex of this edge */
+  default T target() {
+    return type().targetType().fromRaw(
+      graph().raw().target( raw() )
+    );
+  }
+
+
+  @Override default
+  <X> X get(Property<ET,X> property) {
+    return graph().raw().<X>getPropertyE(raw(), property);
+  }
+
+  @Override default
+  <X> E set(Property<ET,X> property, X value) {
+
+    graph().raw().setPropertyE(raw(), property, value);
+    return self();
+  }
+
+}

src/main/java/com/bio4j/angulillos/TypedElement.java → src/main/java/com/bio4j/angulillos/AnyElementType.java

@@ -1,5 +1,7 @@
 package com.bio4j.angulillos;
 
+import java.util.Set;
+
 /*
   ## Elements
 
@@ -13,6 +15,12 @@
 
   `E` refers to the element itself, and `ET` its type. You cannot define one without defining the other.
 */
+public interface AnyElementType extends HasLabel {
+
+  AnyTypedGraph graph();
+  Set<AnyProperty> properties();
+}
+
 interface TypedElement <
   F  extends      TypedElement<F,FT, G,RF>,
   FT extends TypedElement.Type<F,FT, G,RF>,
@@ -31,12 +39,11 @@ interface Type <
     FT extends TypedElement.Type<F,FT, G,RF>,
     G    extends TypedGraph<G,?,?>,
     RF
-  > {
+  > extends AnyElementType {
+    public G graph();
+
     /* Constructs a value of the typed element of this type */
     F fromRaw(RF rawElem);
-
-    // NOTE: this should be final, but interface cannot have final methods
-    default String _label() { return getClass().getCanonicalName(); }
   }
 
 
@@ -50,7 +57,7 @@ interface Type <
   RF raw();
 
   /* The graph in which this element lives. */
-  G graph();
+  default G graph() { return type().graph(); }
 
   /* The `get` method lets you get the value of a `property` which this element has. For that, you pass as an argument the [property](Property.java.md). Note that the type bounds only allow properties of this element. */
   <X> X get(Property<FT,X> property);

src/main/java/com/bio4j/angulillos/AnyProperty.java

@@ -0,0 +1,24 @@
+package com.bio4j.angulillos;
+
+/*
+  ## Properties
+
+  A property of the [Element](TypedElement.java.md) of type `FT`, with value type `X`.
+*/
+public interface AnyProperty extends
+  HasLabel,
+  HasFromArity {
+
+  AnyElementType elementType();
+  Class<?> valueClass();
+}
+
+// TODO: make it public
+interface Property<
+  FT extends TypedElement.Type<?,FT,?,?>,
+  X
+> extends AnyProperty {
+
+  FT elementType();
+  Class<X> valueClass();
+}