json: tojson must not add #J prefix.

* lib.c (out_json_rec): In the CONS case, if ctx is null bail
and report and invalid object. This lets us call the function
with a null context.
(tojson): Do not support (json ...) syntax. Instead of
obj_print, pass the object directly to out_json_rec.

* txr.1: Do not mention handling json macro syntax.
Common leading text factored out of bulleted paragraphs section.

2 files changed, 12 insertions, 36 deletions

diff --git a/lib.c b/lib.c
index aafc933a..1d2c65b7 100644
--- a/lib.c
+++ b/lib.c
@@ -12644,7 +12644,7 @@ static void out_json_rec(val obj, val out, struct strm_ctx *ctx)
     }
     break;
   case CONS:
-    {
+    if (ctx != 0) {
       val sym = car(obj);
       if (sym == hash_lit_s) {
         val save_indent;
@@ -13461,23 +13461,11 @@ val tostringp(val obj)
 
 val tojson(val obj, val flat)
 {
-  if (consp(obj) && eq(car(obj), json_s)) {
-    val ss = make_string_output_stream();
-    if (default_null_arg(flat))
-      set_indent_mode(ss, num_fast(indent_foff));
-    obj_print(obj, ss, nil);
-    return get_string_from_stream(ss);
-  } else {
-    val json = cons(json_s, cons(quote_s, cons(obj, nil)));
-    val ss = make_string_output_stream();
-    if (default_null_arg(flat))
-      set_indent_mode(ss, num_fast(indent_foff));
-    obj_print(json, ss, nil);
-    rcyc_pop(&json);
-    rcyc_pop(&json);
-    rcyc_pop(&json);
-    return get_string_from_stream(ss);
-  }
+  val ss = make_string_output_stream();
+  if (default_null_arg(flat))
+    set_indent_mode(ss, num_fast(indent_foff));
+  out_json_rec(obj, ss, 0);
+  return get_string_from_stream(ss);
 }
 
 val display_width(val obj)
diff --git a/txr.1 b/txr.1
index b9196a05..cf692fd5 100644
--- a/txr.1
+++ b/txr.1
@@ -71854,18 +71854,6 @@ function converts
 .meta obj
 into JSON notation, returned as a character string.
 
-If
-.meta obj
-is
-.code json
-macro syntax generated by the parser, or else generated programmatically in a compatible way,
-then this is converted back into JSON syntax.
-
-Otherwise if
-.meta obj
-conforms to the conventions by which JSON objects are represented in Lisp,
-it is converted to JSON syntax also.
-
 The behavior is unspecified if
 .meta obj
 or any component of
@@ -71873,10 +71861,10 @@ or any component of
 is an object incompatible with the JSON representation conventions.
 An exception may be thrown.
 
-An object conforms to the JSON representation conventions if:
+An object conforms to the JSON representation conventions if it is:
 .RS
 .IP 1.
-It is one of the symbols
+one of the symbols
 .codn nil ,
 .code t
 or
@@ -71888,13 +71876,13 @@ and
 .codn null ,
 respectively.
 .IP 2.
-It is a floating-point number.
+a floating-point number.
 .IP 3.
-It is a character string.
+a character string.
 .IP 4.
-It is a vector of JSON-conforming objects.
+a vector of JSON-conforming objects.
 .IP 5.
-It is a hash table whose keys and values are JSON-conforming objects.
+a hash table whose keys and values are JSON-conforming objects.
 .RE
 .IP
 Note that if unless the keys in a hash table are all strings, nonstandard JSON