last, butlast: become accessors, get optional arg.

* eval.c (optimize_qquote_form): Pass nil to default
new argument of butlast.
(me_whilet, me_iflet_whenlet): Likewise for last.
(eval_init): Add optional argument to registration
of last and butlast intrinsics.

* lib.c (last, butlast): Support optional numeric
argument, like in Common Lisp.

* lib.h (last, butlast): Declarations updated.

* share/txr/stdlib/place.tl (last, butlast): New
place macros.

* txr.1: Updated documentation. The description of
last is now moved into the sequence functions
section.

1 files changed, 2 insertions, 2 deletions

diff --git a/lib.h b/lib.h
index 5092d73d..30d4bd5c 100644
--- a/lib.h
+++ b/lib.h
@@ -507,7 +507,7 @@ loc listref_l(val list, val ind);
 loc tail(val cons);
 loc term(loc head);
 loc lastcons(val list);
-val last(val list);
+val last(val list, val n);
 val nthlast(val pos, val list);
 val nthcdr(val pos, val list);
 val butlastn(val n, val list);
@@ -964,7 +964,7 @@ val ref(val seq, val ind);
 val refset(val seq, val ind, val newval);
 val dwim_set(val seq, val ind_range, val newval);
 val dwim_del(val seq, val ind_range);
-val butlast(val seq);
+val butlast(val seq, val idx);
 val replace(val seq, val items, val from, val to);
 val update(val seq, val fun);
 val search(val seq, val key, val from, val to);