From 1777ba3dc87c62cf18cd178f2055369979907dc8 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Tue, 3 Sep 2019 23:29:24 -0700
Subject: New function: tailp.

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

* lib.c (tailp): New function.

* lib.h (tailp): Declared.

* txr.1: Documented.
---
 lib.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

(limited to 'lib.c')

diff --git a/lib.c b/lib.c
index 374b038a..ebcd1670 100644
--- a/lib.c
+++ b/lib.c
@@ -1682,6 +1682,16 @@ val ldiff_old(val list1, val list2)
   return make_like(out, list_orig);
 }
 
+val tailp(val obj, val list)
+{
+  while (obj != list) {
+    if (atom(list))
+      return nil;
+    list = cdr(list);
+  }
+  return t;
+}
+
 val memq(val obj, val list)
 {
   val list_orig = list;
-- 
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