From dae9271da2babb8879c03946f106c64f2538ceb8 Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Thu, 13 Dec 2018 06:28:50 -0800
Subject: nzerop: new function.

* arith.c (nzerop): New function.

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

* lib.h (nzerop): Declared.

* txr.1: Documented.
---
 arith.c | 22 ++++++++++++++++++++++
 eval.c  |  1 +
 lib.h   |  1 +
 txr.1   | 25 ++++++++++++++++++++++++-
 4 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/arith.c b/arith.c
index 084d8cf5..67fa75c2 100644
--- a/arith.c
+++ b/arith.c
@@ -1557,6 +1557,28 @@ val zerop(val num)
   }
 }
 
+val nzerop(val num)
+{
+  val self = lit("nzerop");
+
+  if (num == zero)
+    return nil;
+
+  switch (type(num)) {
+  case NUM:
+  case BGNUM:
+    return t;
+  case FLNUM:
+    return tnil(c_flo(num, self) != 0.0);
+  case CHR:
+    return tnil(num != chr(0));
+  case RNG:
+    return tnil(nzerop(from(num)) || nzerop(to(num)));
+  default:
+    not_number(self, num);
+  }
+}
+
 val plusp(val num)
 {
   val self = lit("plusp");
diff --git a/eval.c b/eval.c
index b26dc5b1..9cfeba03 100644
--- a/eval.c
+++ b/eval.c
@@ -6445,6 +6445,7 @@ void eval_init(void)
   reg_fun(intern(lit("numberp"), user_package), func_n1(numberp));
 
   reg_fun(intern(lit("zerop"), user_package), func_n1(zerop));
+  reg_fun(intern(lit("nzerop"), user_package), func_n1(nzerop));
   reg_fun(intern(lit("plusp"), user_package), func_n1(plusp));
   reg_fun(intern(lit("minusp"), user_package), func_n1(minusp));
   reg_fun(intern(lit("evenp"), user_package), func_n1(evenp));
diff --git a/lib.h b/lib.h
index d74304db..6570d904 100644
--- a/lib.h
+++ b/lib.h
@@ -685,6 +685,7 @@ val wrap_star(val start, val end, val num);
 val wrap(val start, val end, val num);
 val divi(val anum, val bnum);
 val zerop(val num);
+val nzerop(val num);
 val plusp(val num);
 val minusp(val num);
 val evenp(val num);
diff --git a/txr.1 b/txr.1
index 19b0580d..4d1249df 100644
--- a/txr.1
+++ b/txr.1
@@ -35770,9 +35770,10 @@ a
 or
 .codn float .
 
-.coNP Function @ zerop
+.coNP Functions @ zerop and @ nzerop
 .synb
 .mets (zerop << number )
+.mets (nzerop << number )
 .syne
 .desc
 The
@@ -35797,6 +35798,28 @@ and
 .code nil
 for all other characters.
 
+If
+.meta number
+is a range, then
+.code zerop
+returns
+.code t
+if both of the range endpoints individually satisfy
+.codn zerop .
+
+The
+.code nzerop
+function is the logical inverse of
+.codn zerop :
+it returns
+.code t
+for those arguments for which
+.code zerop
+returns
+.code nil
+and
+.IR "vice versa" .
+
 .coNP Functions @ plusp and @ minusp
 .synb
 .mets (plusp << number )
-- 
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