mkstring char argument is optional.

* eval.c (eval_init): Update registration of mkstring intrinsic
to make second argument optional.

* lib.c (mkstring): Default second argument to space.

* txr.1: Documentation of mkstring updated.

3 files changed, 8 insertions, 3 deletions

diff --git a/eval.c b/eval.c
index 187273c5..d1c3cc8c 100644
--- a/eval.c
+++ b/eval.c
@@ -5927,7 +5927,7 @@ void eval_init(void)
   reg_fun(intern(lit("packagep"), user_package), func_n1(packagep));
   reg_fun(intern(lit("keywordp"), user_package), func_n1(keywordp));
   reg_fun(intern(lit("bindable"), user_package), func_n1(bindable));
-  reg_fun(intern(lit("mkstring"), user_package), func_n2(mkstring));
+  reg_fun(intern(lit("mkstring"), user_package), func_n2o(mkstring, 1));
   reg_fun(intern(lit("copy-str"), user_package), func_n1(copy_str));
   reg_fun(intern(lit("upcase-str"), user_package), func_n1(upcase_str));
   reg_fun(intern(lit("downcase-str"), user_package), func_n1(downcase_str));
diff --git a/lib.c b/lib.c
index f1309a72..3dd2c536 100644
--- a/lib.c
+++ b/lib.c
@@ -3313,7 +3313,7 @@ val string_8bit_size(const unsigned char *str, size_t sz)
   return string_own(wstr);
 }
 
-val mkstring(val len, val ch)
+val mkstring(val len, val ch_in)
 {
   size_t l = if3(minusp(len),
                  (uw_throwf(error_s, lit("mkstring: negative size ~s specified"),
@@ -3321,6 +3321,7 @@ val mkstring(val len, val ch)
                  c_num(len));
   wchar_t *str = chk_wmalloc(l + 1);
   val s = string_own(str);
+  val ch = default_arg_strict(ch_in, chr(' '));
   wmemset(str, c_chr(ch), l);
   str[l] = 0;
   s->st.len = len;
diff --git a/txr.1 b/txr.1
index 8a5d815e..d758e28e 100644
--- a/txr.1
+++ b/txr.1
@@ -20427,7 +20427,7 @@ ranges are immutable.
 .SS* Characters and Strings
 .coNP Function @ mkstring
 .synb
-.mets (mkstring < length << char )
+.mets (mkstring < length <> [ char ])
 .syne
 .desc
 The
@@ -20440,6 +20440,10 @@ with
 .metn char ,
 which must be a character value.
 
+If the optional argument
+.meta char
+is not specified, it defaults to the space character.
+
 .coNP Function @ copy-str
 .synb
 .mets (copy-str << string )