symdiff: new function.

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

* lib.c (symdiff): New function.

* lib.h (us_car_p, us_cdr_p): New inline functions.
(symdiff): Declared.

* txr.1: Documented, also fixing issues not related to
symdiff doc.

1 files changed, 3 insertions, 0 deletions

diff --git a/lib.h b/lib.h
index 08e7acb2..866d48b3 100644
--- a/lib.h
+++ b/lib.h
@@ -544,6 +544,8 @@ val car(val cons);
 val cdr(val cons);
 INLINE val us_car(val cons) { return cons->c.car; }
 INLINE val us_cdr(val cons) { return cons->c.cdr; }
+INLINE val *us_car_p(val cons) { return &cons->c.car; }
+INLINE val *us_cdr_p(val cons) { return &cons->c.cdr; }
 val rplaca(val cons, val new_car);
 val rplacd(val cons, val new_car);
 val sys_rplaca(val cons, val new_car);
@@ -1079,6 +1081,7 @@ val drop_until(val pred, val seq, val keyfun);
 val in(val seq, val key, val testfun, val keyfun);
 val set_diff(val list1, val list2, val testfun, val keyfun);
 val diff(val seq1, val seq2, val testfun, val keyfun);
+val symdiff(val seq1, val seq2, val testfun, val keyfun);
 val isec(val list1, val list2, val testfun, val keyfun);
 val uni(val list1, val list2, val testfun, val keyfun);
 val copy(val seq);