Moving sys:capture-cont to call/cc style API.

* unwind.c (revive_cont): Don't wrap cons cell around
passed arg; just pass it directly. We don't need
that convention any more.

* capture_cont: Take functional argument. Pass the captured
continuation to the function. If the function returns,
return whatever it returned. When resuming, return the
continuation argument.
(uw_capture_cont): Take functional second argument
and pass to capture_cont. Context form becomes third
argument.
(uw_late_init): Update registration of sys:capture-cont
to three arguments, two required.

* unwind.h (uw_capture_cont): Declaration updated.

* share/txr/stdlib/yield.tl (sys:yield-impl): Not
needed any more; all this was doing was implementing
a call/cc style interface around sys:capture-cont
which can now be used directly.
(yield-from): Use sys:capture-cont directly.
(suspend): Simplified to the point of triviality
with new sys:capture-cont.

* txr.1: Documented.

1 files changed, 1 insertions, 1 deletions

diff --git a/unwind.h b/unwind.h
index bcf8d185..5fccabc0 100644
--- a/unwind.h
+++ b/unwind.h
@@ -125,7 +125,7 @@ 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_form);
+val uw_capture_cont(val tag, val fun, val ctx_form);
 void uw_init(void);
 void uw_late_init(void);