Implementing package foreign symbol concept.

* eval.c (eval_init): Register new intrinsics:
package-local-symbols, package-foreign-symbols, use-sym,
unuse-sym, use-package, unuse-package, unintern.

* gc.c (mark_obj): Mark new hidhash member of
struct package.

* lib.c (make_package): Initialize new hidhash
member of struct package.
(lookup_package): New static function.
(find_package): Allow string or symbol argument.
(get_package): New static function.
(delete_package, package_symbols): Use get_package for
flexible package argument; delete_package removes
symbols from other packages via unuse_package.
(package_local_symbols, package_foreign_symbols): New
functions.
(use_sym, unuse_sym): New functions.
(resolve_package_designators): New static function.
(use_package, unuse_package): New functions.
(symbol_present): New static function.
(intern): Revised with get_package for flexible
package argument.
(unintern): New function.
(rehome_sym): Use get_package. Semantics revised.
(obj_print_impl): Use symbol_present function to
determine whether object is visible in *package* and
can be printed without a prefix, rather than naive
home package test.

* lib.h (struct package): New member, hidhash.
(package_local_symbols, package_foreign_symbols, use_sym,
unuse_sym, use_package, unuse_package, unintern): Declared.

* txr.1: Documentation updated. Extended section introducing
the design of packages, and argument conventions. New
functions described. Existing function descriptions revised,
particularly rehome-sym.  Missing description of
delete-package added.

1 files changed, 7 insertions, 0 deletions

diff --git a/eval.c b/eval.c
index e649af91..06df270d 100644
--- a/eval.c
+++ b/eval.c
@@ -5211,7 +5211,14 @@ void eval_init(void)
   reg_fun(intern(lit("package-alist"), user_package), func_n0(package_alist));
   reg_fun(intern(lit("package-name"), user_package), func_n1(package_name));
   reg_fun(intern(lit("package-symbols"), user_package), func_n1(package_symbols));
+  reg_fun(intern(lit("package-local-symbols"), user_package), func_n1(package_local_symbols));
+  reg_fun(intern(lit("package-foreign-symbols"), user_package), func_n1(package_foreign_symbols));
+  reg_fun(intern(lit("use-sym"), user_package), func_n2o(use_sym, 1));
+  reg_fun(intern(lit("unuse-sym"), user_package), func_n2o(unuse_sym, 1));
+  reg_fun(intern(lit("use-package"), user_package), func_n2o(use_package, 1));
+  reg_fun(intern(lit("unuse-package"), user_package), func_n2o(unuse_package, 1));
   reg_fun(intern(lit("intern"), user_package), func_n2o(intern, 1));
+  reg_fun(intern(lit("unintern"), user_package), func_n2o(unintern, 1));
   reg_fun(intern(lit("rehome-sym"), user_package), func_n2o(rehome_sym, 1));
   reg_fun(intern(lit("symbolp"), user_package), func_n1(symbolp));
   reg_fun(intern(lit("symbol-name"), user_package), func_n1(symbol_name));