Implement *package* special var; package overhaul.

* eval.c (load): Rebind *package* in the local dynamic
environment already established for the sake of *load-path*.
By doing this we cause *package* to be restored to its
prior value, which allows the loaded file to alter it.
Common Lisp works this way.
(eval_init): Register *package* variable, with the
user package as its default value.

* lib.c (package_s): New symbol variable.
(intern, rehome_sym): Default the package argument to the
current package, not to user_package.
(get_user_package, get_system_package, get_keyword_package):
Functions removed.
(get_current_package): New function.
(obj_print_impl): Revise symbol printing. Keyword and
uninterned symbols are printed with : and #: prefixes.
The remainder are printed with a package prefix if their
home package isn't the current package.

* lib.h (keyword_package, user_package, system_package): These
macros are just straight aliases for the global
variables, not going through the lookup mechanism,
which was pointless.
(cur_package): New macro.
(package_s): Declared.
(get_current_package): Declared.

* lisplib.c (lisplib_try_load): Establish a local
dynamic environment, and bind the *package* variable
to the user package which the library modules expect.

* parser.c (find_matching_syms, provide_completions):
Treat unqualified symbols in the current package
rather than user package.

* parser.y (sym_helper): Intern unqualified symbols
in the current package, not user package.

* txr.1: Document that the variables user-package,
system-package and keyword-package should not be modified.
Document the *package* special variable, and that intern and
rehome-sym default their package argument to its value. (Here
we get rid of wrong references to the undocumented variable
*user-package*).

1 files changed, 2 insertions, 2 deletions

diff --git a/parser.c b/parser.c
index 655ee8f1..bf243711 100644
--- a/parser.c
+++ b/parser.c
@@ -634,7 +634,7 @@ static void find_matching_syms(lino_completions_t *cpl,
                                val line_prefix, char par,
                                val force_qualify)
 {
-  val qualify = tnil(force_qualify || package != user_package);
+  val qualify = tnil(force_qualify || package != cur_package);
   val pkg_name = if2(qualify,
                      if3(package == keyword_package && !force_qualify,
                          lit(""),
@@ -761,7 +761,7 @@ static void provide_completions(const char *data,
       int dwim = (prev == '[');
       char par = (!pprev || (!quote && !meth && !ppar) || dwim) ? prev : 0;
 
-      find_matching_syms(cpl, or2(package, user_package),
+      find_matching_syms(cpl, or2(package, cur_package),
                          sym_pfx, line_pfx, par, if2(package, null(keyword)));
     }
   }