end
end
+# Something that can be cloned
+#
+# This interface introduces the `clone` method used to duplicate an instance
+# Its specific semantic is let to the subclasses.
+interface Cloneable
+ # Duplicate `self`
+ #
+ # The specific semantic of this method is let to the subclasses;
+ # Especially, if (and how) attributes are cloned (depth vs. shallow).
+ #
+ # As a rule of thumb, the principle of least astonishment should
+ # be used to guide the semantic.
+ #
+ # Note that as the returned clone depends on the semantic,
+ # the `==` method, if redefined, should ensure the equality
+ # between an object and its clone.
+ fun clone: SELF is abstract
+end
+
# A numeric value supporting mathematical operations
interface Numeric
super Comparable