From 8cfffbeccdab028f780dcaf9f4ffaf97d7393a1e Mon Sep 17 00:00:00 2001
From: Daniel Cerqueira <dan.git@lispclub.com>
Date: Sun, 16 Aug 2026 12:59:14 +0100
Subject: add diff operator

 - and remove and diff and differ
 - and update documentation
 - and update all lali scripts
---
 liblali.c | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

(limited to 'liblali.c')

diff --git a/liblali.c b/liblali.c
index 38f28b5..cfd4d76 100644
--- a/liblali.c
+++ b/liblali.c
@@ -847,13 +847,22 @@ Object *primitiveAtom(Object **args, GC_PARAM) {
  * }
  */
 
-Object *primitiveDif(Object **args, GC_PARAM) {
+Object *primitiveDiff(Object **args, GC_PARAM) {
   Object *first = (*args)->car, *second = (*args)->cdr->car;
 
   if ((first->type == TYPE_NUMBER && second->type == TYPE_NUMBER) ||
       (first->type == TYPE_STRING && second->type == TYPE_STRING) ||
       (first->type == TYPE_SYMBOL && second->type == TYPE_SYMBOL))
     return strcmp(first->string, second->string) ? t : f;
+  else if (first->type == TYPE_CONS && second->type == TYPE_CONS) {
+	 for (; (first->cdr != nil || second->cdr != nil);
+			first = first->cdr, second = second->cdr) {
+		if (strcmp(first->string, second->string))
+		  return t;
+	 }
+	 return (strcmp(first->car->string, second->car->string) ||
+				(first->cdr != nil && second->cdr != nil)) ? t : f;
+  }
   else
     return t;
 }
@@ -1282,7 +1291,7 @@ Primitive primitives[] = {
   { "space",   1,  1, primitiveSpace        },
   { "atom",    1,  1, primitiveAtom         },
   /* { "eq",      2,  2, primitiveEq           }, */
-  { "dif",     2,  2, primitiveDif          },
+  { "diff",    2,  2, primitiveDiff         },
   { "car",     1,  1, primitiveCar          },
   { "cdr",     1,  1, primitiveCdr          },
   { "cons",    2,  2, primitiveCons         },
@@ -1631,7 +1640,7 @@ static char *stdlib = LISP(
   (defmacro defun (name params . body)
     (list (quote set) (list quote name) (list (quote lambda) params . body)))
 
-  (defun not (x) (fill ((dif x n) n)
+  (defun not (x) (fill ((diff x n) n)
                        (x t)
                        (f f)))
 
@@ -1639,7 +1648,7 @@ static char *stdlib = LISP(
 
   (defun listp (x) (not (atom x)))
 
-  (defun zerop (x) (not (dif x +0)))
+  (defun zerop (x) (not (diff x +0)))
 
   (defmacro and args
     (fill ((algo args) t)
@@ -1664,13 +1673,8 @@ static char *stdlib = LISP(
 
   (defun singul (x) (not (consp x)))
 
-  (defun differ (x y)
-    (fill ((and (consp x) (consp y)) (dif x y))
-          (f (or (differ (car x) (car y))
-                 (differ (cdr x) (cdr y))))))
-
   (defun nth (num xs)
-    (fill ((dif num +0) (car xs))
+    (fill ((diff num +0) (car xs))
           (f (nth (- num +1) (cdr xs)))))
 
   (defun append (xs y)
-- 
cgit