diff --git a/lib/F/Function.pm b/lib/F/Function.pm
index ce69d8bf..d99d4276 100644
--- a/lib/F/Function.pm
+++ b/lib/F/Function.pm
@@ -38,6 +38,7 @@ sub desc {
     return "function '$$func{name}'";
 }
 
+# all WantNeeds which belong to this function
 sub arguments {
     my $func = shift;
 
@@ -53,6 +54,7 @@ sub arguments {
     return @wn;
 }
 
+# all Returns and ReturnPairs which belong to this function
 sub returns {
     my $func = shift;
 
diff --git a/lib/F/Regex.pm b/lib/F/Regex.pm
index 724c2135..714154e9 100644
--- a/lib/F/Regex.pm
+++ b/lib/F/Regex.pm
@@ -30,7 +30,7 @@ sub desc {
     my $first = length $rgx->{value} > 13  ?
         substr($rgx->{value}, 0, 10).'...' :
         $rgx->{value};
-    return "Regex /$first/";
+    return "regex /$first/";
 }
 
 sub perl_fmt {
diff --git a/lib/Ferret/Core/FF.pm b/lib/Ferret/Core/FF.pm
index 7ab66596..0e819d15 100644
--- a/lib/Ferret/Core/FF.pm
+++ b/lib/Ferret/Core/FF.pm
@@ -454,7 +454,8 @@ sub method_event_def {
 # type definitions.
 sub typedef {
     my ($scope, $scope_or_class, $type_name, $code, $lazy) = @_;
-    my $typedef = sub {
+    my $f = $scope->f;
+    my $create_typedef = sub {
 
         # this sub returns a function which returns Ferret true if
         # a method requirement is satisfied.
@@ -530,21 +531,30 @@ sub typedef {
 
         };
 
+        # create a prototype.
+        my $proto = Ferret::Prototype->new($f) if $lazy;
+
         # create a function.
         my $func = ffunction(sub {
             my (undef, $args) = @_;
             my $obj = $args->{obj};
+
+            # already an instance of this type.
+            return $obj if $proto && $obj->has_parent($proto);
+
+            # compute the result and make it an instance of this type.
             my $res = $code->($obj, $create_can, $transform);
+            $res->add_parent($proto) if $proto;
+
             return $res || Ferret::undefined;
         }, $type_name, '$obj');
 
+        $func->set_property(proto => $proto) if $proto;
         $func->{is_typedef} = 1;
         return $func;
     };
 
-    $scope_or_class->set_property($type_name =>
-        $lazy ? [ $typedef ] : $typedef->()
-    ); # TODO: pos
+    $scope_or_class->set_property($type_name => $create_typedef->());
 }
 
 sub typedef_check {
diff --git a/lib/Ferret/Object.pm b/lib/Ferret/Object.pm
index b5c33524..0e6c65ad 100644
--- a/lib/Ferret/Object.pm
+++ b/lib/Ferret/Object.pm
@@ -489,7 +489,7 @@ sub _uniq {
 sub parent_classes {
     my ($obj, @classes) = shift;
     foreach my $parent ($obj->parents) {
-        next unless $parent->{is_proto};
+        next unless $parent->{is_proto} && $parent->{proto_class};
         push @classes, $parent->{proto_class};
     }
     return @classes;