Use null_string throughout code base.

* eval.c (load): Use null_string instead of lit("").

* lib.c (obj_init): Likewise.

* match.c (LOG_MATCH, LOG_MISMATCH, do_txeval): Likewise.

* parser.c (regex_parse, lisp_parse_impl, find_matching_syms):
Likewise.

* stream.c (do_parse_mode): Likewise.

* txr.c (sysroot_init): Likewise.
(txr_main): Replace string(L"") with null_string.

6 files changed, 12 insertions, 11 deletions

diff --git a/eval.c b/eval.c
index dc0c97b3..5b1f4818 100644
--- a/eval.c
+++ b/eval.c
@@ -4663,7 +4663,7 @@ val load(val target)
 
   open_txr_file(path, &txr_lisp_p, &name, &stream, self);
 
-  if (match_str(or2(get_line(stream), lit("")), lit("#!"), nil))
+  if (match_str(or2(get_line(stream), null_string), lit("#!"), nil))
     parser_set_lineno(self, stream, two);
   else
     seek_stream(stream, zero, from_start_k);
diff --git a/lib.c b/lib.c
index 03d6cead..2f3f6603 100644
--- a/lib.c
+++ b/lib.c
@@ -13166,7 +13166,7 @@ static void obj_init(void)
 
   args_k = intern(lit("args"), keyword_package);
   nothrow_k = intern(lit("nothrow"), keyword_package);
-  colon_k = intern(lit(""), keyword_package);
+  colon_k = intern(null_string, keyword_package);
   auto_k = intern(lit("auto"), keyword_package);
   fun_k = intern(lit("fun"), keyword_package);
   wrap_k = intern(lit("wrap"), keyword_package);
diff --git a/match.c b/match.c
index e2d01b80..81cf7c8d 100644
--- a/match.c
+++ b/match.c
@@ -519,14 +519,14 @@ typedef val (*h_match_func)(match_line_ctx *c);
           plus(c->pos, c->base), c->file, c->data_lineno, nao);         \
   debuglf(elem, lit("  ~a"), c->dataline, nao);                         \
   if (c_num(c->pos, lit("txr")) < 77)                                   \
-    debuglf(elem, lit("  ~*a^"), c->pos, lit(""), nao)
+    debuglf(elem, lit("  ~*a^"), c->pos, null_string, nao)
 
 #define LOG_MATCH(KIND, EXTENT)                                         \
   debuglf(elem, lit(KIND " matched, position ~a-~a (~a:~d)"),           \
           plus(c->pos, c->base), EXTENT, c->file, c->data_lineno, nao); \
   debuglf(elem, lit("  ~a"), c->dataline, nao);                         \
   if (c_num(EXTENT, lit("txr")) < 77)                                   \
-    debuglf(elem, lit("  ~*a~<*a^"), c->pos, lit(""),                   \
+    debuglf(elem, lit("  ~*a~<*a^"), c->pos, null_string,               \
               minus(EXTENT, c->pos), lit("^"), nao)
 
 #define elem_bind(elem_var, directive_var, specline)    \
@@ -2005,7 +2005,7 @@ static val do_txeval(val spec, val form, val bindings, val allow_unbound)
     uw_catch (exc_sym, exc) {
       val msg = if3(consp(exc), car(exc), exc);
 
-      if (stringp(msg) && !equal(msg, lit("")) &&
+      if (stringp(msg) && !equal(msg, null_string) &&
           chr_str(msg, zero) == chr('('))
       {
         uw_throw (exc_sym, exc);
diff --git a/parser.c b/parser.c
index 645b933f..4609546b 100644
--- a/parser.c
+++ b/parser.c
@@ -620,7 +620,8 @@ val regex_parse(val string, val error_stream)
 
   {
     int gc = gc_state(0);
-    parse(&parser, if3(std_error != std_null, lit("regex"), lit("")), prime_regex);
+    parse(&parser, if3(std_error != std_null, lit("regex"), null_string),
+          prime_regex);
     gc_state(gc);
   }
 
@@ -668,7 +669,7 @@ static val lisp_parse_impl(val self, enum prime_parser prime,
 
   for (;;) {
     int gc = gc_state(0);
-    parse(pi, if3(std_error != std_null, name, lit("")), prime);
+    parse(pi, if3(std_error != std_null, name, null_string), prime);
     mut(parser);
     gc_state(gc);
 
@@ -962,7 +963,7 @@ static void find_matching_syms(lino_completions_t *cpl,
   val qualify = tnil(force_qualify || !is_cur);
   val pkg_name = if2(qualify,
                      if3(package == keyword_package && !force_qualify,
-                         lit(""),
+                         null_string,
                          package_name(package)));
   val syms = ((kind == 'S' || kind == 'M')
               ? hash_keys((get_slot_syms(package, is_cur, tnil(kind == 'M'))))
diff --git a/stream.c b/stream.c
index 90c1e34f..951815a3 100644
--- a/stream.c
+++ b/stream.c
@@ -1443,7 +1443,7 @@ static struct stdio_mode do_parse_mode(val mode_str, struct stdio_mode m_dfl,
                                        val self)
 {
   struct stdio_mode m = stdio_mode_init_blank;
-  const wchar_t *ms = c_str(default_arg_strict(mode_str, lit("")), self);
+  const wchar_t *ms = c_str(default_arg_strict(mode_str, null_string), self);
   int nredir = 0;
 
   switch (*ms) {
diff --git a/txr.c b/txr.c
index 0a9451eb..e94be080 100644
--- a/txr.c
+++ b/txr.c
@@ -329,7 +329,7 @@ static void sysroot_init(void)
   prog_dir = dir_name(prog_path);
 
   if (ref(prog_dir, negone) != chr(psc[0]))
-    prog_dir = scat3(prog_dir, chr(psc[0]), lit(""));
+    prog_dir = scat3(prog_dir, chr(psc[0]), null_string);
 
   if (!(maybe_sysroot(lit(TXR_REL_PATH)) ||
         maybe_sysroot(lit(TXR_REL_PATH EXE_SUFF)) ||
@@ -668,7 +668,7 @@ int txr_main(int argc, char **argv)
       else if (deflist)
         bindings = cons(cons(sym, car(deflist)), bindings);
       else
-        bindings = cons(cons(sym, string(L"")), bindings);
+        bindings = cons(cons(sym, null_string), bindings);
 
       match_reg_var(sym);