macro-time: interleave evaluation and expansion.

* eval.c (do_expand): When expanding the macro-time
form, do not macro-expand it entirely and then evaluate.
Rather, expand each argument form and evaluate.
This way earlier forms can make global definitions
which are used while macro-expanding later definitions.

* txr.1: Behavior documented.

2 files changed, 19 insertions, 2 deletions

diff --git a/eval.c b/eval.c
index 313eabe1..1114846b 100644
--- a/eval.c
+++ b/eval.c
@@ -3821,8 +3821,12 @@ static val do_expand(val form, val menv)
                                           body, body_ex)))), form);
     } else if (sym == macro_time_s) {
       val args = rest(form);
-      val args_ex = expand_forms(args, menv);
-      val result = eval_progn(args_ex, make_env(nil, nil, nil), args);
+      val result = nil;
+      for (; args; args = cdr(args)) {
+        val arg = car(args);
+        val arg_ex = expand(arg, menv);
+        result = eval(arg_ex, nil, args);
+      }
       return maybe_quote(result);
     } else if (sym == macrolet_s) {
       return expand_macrolet(form, menv);
diff --git a/txr.1 b/txr.1
index 9376d51a..f01e2537 100644
--- a/txr.1
+++ b/txr.1
@@ -27262,6 +27262,19 @@ The special behavior of
 is that the evaluation takes place during
 the expansion phase, rather than during the evaluation phase.
 
+Also,
+.code macro-time
+macro-expands each
+.meta form
+and evaluates it before processing the next
+.meta form
+in the same way. Thus, for instance, if a
+.meta form
+introduces a global definition, that definition will be visible not
+only during the evaluation of a subsequent
+.metn form ,
+but also during its macro-expansion time.
+
 During the expansion phase, all
 .code macro-time
 expressions which occur in a context