tree: introduce copy-tnode.

* lib.c (copy): Handle TNOD casee via copy_tnode.

* tree.c (copy_tnode): New function.
(tree_init): copy-tnode intrinsic registered.

* tree.h (copy_tnode): Declared.

* txr.1: copy function documented as handling tnode type via
copy-tnode. That function is documented.

1 files changed, 1 insertions, 0 deletions

diff --git a/tree.h b/tree.h
index 94270b4b..0f056429 100644
--- a/tree.h
+++ b/tree.h
@@ -34,6 +34,7 @@ val tnodep(val obj);
 val left(val node);
 val right(val node);
 val key(val node);
+val copy_tnode(val node);
 val tree(val keys, val key_fn, val less_fn, val equal_fn);
 val treep(val obj);
 val tree_insert_node(val tree, val node);