* eval.c (not_null): New static function.

(eval_init): Use null_f in existing registration of null
and not. Add registration for not_null as "true",
and for null_f as "false".

* txr.1: Documented true and false.

1 files changed, 9 insertions, 2 deletions

diff --git a/eval.c b/eval.c
index d9acfda4..7339281e 100644
--- a/eval.c
+++ b/eval.c
@@ -3057,6 +3057,11 @@ static val and_fun(val vals)
   return item;
 }
 
+static val not_null(val obj)
+{
+  return if3(nilp(obj), nil, t);
+}
+
 static val prinl(val obj, val stream)
 {
   val ret = obj_print(obj, stream);
@@ -3224,8 +3229,10 @@ void eval_init(void)
   reg_fun(intern(lit("typeof"), user_package), func_n1(typeof));
 
   reg_fun(intern(lit("atom"), user_package), func_n1(atom));
-  reg_fun(intern(lit("null"), user_package), func_n1(null));
-  reg_fun(not_s, func_n1(null));
+  reg_fun(intern(lit("null"), user_package), null_f);
+  reg_fun(intern(lit("false"), user_package), null_f);
+  reg_fun(intern(lit("true"), user_package), func_n1(not_null));
+  reg_fun(not_s, null_f);
   reg_fun(intern(lit("consp"), user_package), func_n1(consp));
   reg_fun(intern(lit("listp"), user_package), func_n1(listp));
   reg_fun(intern(lit("proper-listp"), user_package), func_n1(proper_listp));