doc trusts

Author: gfldex

doc/Language/typesystem.pod6

@@ -182,6 +182,23 @@ TODO
 
 =head3 trait C<trusts>
 
+To allow one class to access the private methods of another class use the trait
+C<trusts>. A forward declaration of the tuested class may be required.
+
+    class B {...};
+    class A {
+        trusts B;
+        has $!foo;
+        method !foo { return-rw $!foo }
+        method perl { "A.new(foo => $!foo)" }
+    };
+    class B {
+        has A $.a .= new;
+        method change { $!a!A::foo = 42; self }
+    };
+    say B.new.change;
+    OUTPUT«B.new(a => A.new(foo => 42))␤»
+
 TODO
 
 =head3 Versioning and Authership