Support weak semantics in symbol packages.

A package is weak if it holds weak references to symbols,
meaning that if there are no references to a symbol other than
its entry in a weak package, it can be removed from the
package and reclaimed by the garbage collector.

* eval.c (eval_init): Update registrations for make-package
and sys:make-anon-package to reflect new optional argument.

* lib.c (make_package_common): New argument weak. If it is
true then both the hashes will have weak values.
(make_package, make_anon_package): New optional argument weak.
(obj_init): Add nil argument to calls to make_package. All the
standard packages are regular, not weak.

* lib.h (make_package, make_anon_package): Declarations
updated.

* txr.1: Documented.

1 files changed, 2 insertions, 2 deletions

diff --git a/lib.h b/lib.h
index 330ae34f..fc4dfebd 100644
--- a/lib.h
+++ b/lib.h
@@ -928,8 +928,8 @@ val compl_span_str(val str, val set);
 val break_str(val str, val set);
 val make_sym(val name);
 val gensym(val prefix);
-val make_package(val name);
-val make_anon_package(void);
+val make_package(val name, val weak);
+val make_anon_package(val weak);
 val packagep(val obj);
 val find_package(val name);
 val delete_package(val package);