* arith.c (succ, ssucc, sssucc, pred, ppred, pppred): New functions.

* eval.c (eval_init): Register new functions as intrinsics.

* lib.h (succ, ssucc, sssucc, pred, ppred, pppred): Declared.

* txr.1: Documented.

1 files changed, 30 insertions, 0 deletions

diff --git a/arith.c b/arith.c
index 5d4cdada..23cf66a8 100644
--- a/arith.c
+++ b/arith.c
@@ -1011,6 +1011,36 @@ val oddp(val num)
   }
 }
 
+val succ(val num)
+{
+  return plus(num, one);
+}
+
+val ssucc(val num)
+{
+  return plus(num, two);
+}
+
+val sssucc(val num)
+{
+  return plus(num, three);
+}
+
+val pred(val num)
+{
+  return minus(num, one);
+}
+
+val ppred(val num)
+{
+  return minus(num, two);
+}
+
+val pppred(val num)
+{
+  return minus(num, three);
+}
+
 val gt(val anum, val bnum)
 {
 tail: