+sub end { $_[0]->center->end }
+
+LaTeX::TikZ::Interface->register(
+ circle => sub {
+ shift;
+
+ __PACKAGE__->new(center => $_[0], radius => $_[1]);
+ },
+);
+
+LaTeX::TikZ::Functor->default_rule(
+ (__PACKAGE__) => sub {
+ my ($functor, $set, @args) = @_;
+ $set->new(
+ center => $set->center->$functor(@args),
+ radius => $set->radius,
+ );
+ }
+);