Context form error reporting in sys:capture-cont.

* unwind.c (sys_capture_cont_s): New variable.
(uw_capture_cont): Second argument is now a context
form rather than a symbol; eval_error is used for error
reporting. The form's operator symbol si used in the
error message, or else sys:capture-cont if the
context argument is null or missing.
(uw_late_init): Initialize sys_capture_cont_s.

* unwind.h (uw_capture_cont): Declaration updated.

* txr.1: Documented.

1 files changed, 1 insertions, 1 deletions

diff --git a/unwind.h b/unwind.h
index b2242661..a9b456ae 100644
--- a/unwind.h
+++ b/unwind.h
@@ -124,7 +124,7 @@ uw_frame_t *uw_current_exit_point(void);
 val uw_get_frames(void);
 val uw_find_frame(val extype, val frtype);
 val uw_invoke_catch(val catch_frame, val sym, struct args *);
-val uw_capture_cont(val tag, val ctx);
+val uw_capture_cont(val tag, val ctx_form);
 void uw_init(void);
 void uw_late_init(void);