New accessor: mref.

* eval.c (eval_init): Register mref intrinsic.

* lib.[ch] (mref): New function.

* stdlib/place.tl (sys:mref1): New place.
(mref): New place macro, defined in terms
of sys:merf1, ref place and mref function.

* tests/012/seq.tl: New tests.

* txr.1: Documented.

1 files changed, 12 insertions, 0 deletions

diff --git a/lib.c b/lib.c
index 515d5439..4ce12556 100644
--- a/lib.c
+++ b/lib.c
@@ -13476,6 +13476,18 @@ val dwim_del(val place_p, val seq, val ind_range)
   }
 }
 
+val mref(val obj, varg args)
+{
+  cnum index = 0;
+
+  while (args_more(args, index)) {
+    val idx = args_get(args, &index);
+    obj = funcall1(obj, idx);
+  }
+
+  return obj;
+}
+
 val butlast(val seq, val idx)
 {
   if (listp(seq)) {