Start of fallback package list implementation.

* eval.c (eval_init): Register package-fallback-list and
set-package-fallback-list intrinsics.

* lib.c (package_fallback_list, set_package_fallback_list,
intern_fallback): New functions

* lib.h (package_fallback_list, set_package_fallback_list,
intern_fallback): Declared.

* parser.y (sym_helper): Slightly restructure function
so that the symbol interning is done separately in
the various cases. In the unqualified symbol case,
use intern_fallback to search the fallback list
of the current package.

* share/txr/stdlib/package.tl (defpackage): Implement
:fallback clause.

1 files changed, 2 insertions, 0 deletions

diff --git a/eval.c b/eval.c
index 199bfa0a..e8ac079e 100644
--- a/eval.c
+++ b/eval.c
@@ -5246,6 +5246,8 @@ void eval_init(void)
   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("package-fallback-list"), user_package), func_n1(package_fallback_list));
+  reg_fun(intern(lit("set-package-fallback-list"), user_package), func_n2(set_package_fallback_list));
   reg_fun(intern(lit("symbolp"), user_package), func_n1(symbolp));
   reg_fun(intern(lit("symbol-name"), user_package), func_n1(symbol_name));
   reg_fun(intern(lit("symbol-package"), user_package), func_n1(symbol_package));