13 files changed, 132 insertions, 142 deletions

diff --git a/README.md b/README.md
index c2ed2c1..2bd4b8b 100644
--- a/README.md
+++ b/README.md
@@ -130,23 +130,16 @@ which is `y`:
 
 ### Predicates
 
-`(dif x y)` returns `t` if `x` and `y` refers to different objects, or if they are
-numbers with different values, or if they are string objects with different
-contents:
-
-    (dif +1 +1)               ; f
-    (dif +1 +2)               ; t
-    (dif 'a 'a)               ; f
-    (dif 'a 'b)               ; t
-    (dif t t)                 ; f
-    (dif t f)                 ; t
-    (dif '(a b) '(a b))       ; t
-
-`(differ x y)` returns `t` if `x` and `y` are objects of different structure and
-each of their elements satisfy the `dif` predicate, otherwise `f`:
-
-    (differ '(a b) '(a))      ; t
-    (differ '(a b) '(a b))    ; f
+`(diff x y)` returns `t` if `x` and `y` are different, otherwise `f`:
+
+    (diff +1 +1)              ; f
+    (diff +1 +2)              ; t
+    (diff 'a 'a)              ; f
+    (diff 'a 'b)              ; t
+    (diff t t)                ; f
+    (diff t f)                ; t
+    (diff '(a b) '(a))        ; t
+    (diff '(a b) '(a b))      ; f
 
 `(space x)` returns `t` if `x` is an empty list `()`, otherwise `f`:
 
diff --git a/examples/abacus/reading.lali b/examples/abacus/reading.lali
index 6663bb3..2f34f00 100755
--- a/examples/abacus/reading.lali
+++ b/examples/abacus/reading.lali
@@ -4,47 +4,47 @@
 ;; functions
 (defun random-number (cases)
   (fill
-   ((dif cases +0) (cons (random +9) ()))
+   ((diff cases +0) (cons (random +9) ()))
    (f (cons (random +9) (random-number (- cases +1))))))
 
 (defun number-to-symbol (num)
   (fill
-   ((dif +0 num) '0)
-   ((dif +1 num) '1)
-   ((dif +2 num) '2)
-   ((dif +3 num) '3)
-   ((dif +4 num) '4)
-   ((dif +5 num) '5)
-   ((dif +6 num) '6)
-   ((dif +7 num) '7)
-   ((dif +8 num) '8)
-   ((dif +9 num) '9)))
+   ((diff +0 num) '0)
+   ((diff +1 num) '1)
+   ((diff +2 num) '2)
+   ((diff +3 num) '3)
+   ((diff +4 num) '4)
+   ((diff +5 num) '5)
+   ((diff +6 num) '6)
+   ((diff +7 num) '7)
+   ((diff +8 num) '8)
+   ((diff +9 num) '9)))
 
 (defun number-to-earth-rod (num)
   (fill
-   ((dif +0 num) "[@-@][@@@@-@]")
-   ((dif +1 num) "[@-@][@@@-@@]")
-   ((dif +2 num) "[@-@][@@-@@@]")
-   ((dif +3 num) "[@-@][@-@@@@]")
-   ((dif +4 num) "[@-@][-@@@@@]")
-   ((dif +5 num) "[-@@][@@@@-@]")
-   ((dif +6 num) "[-@@][@@@-@@]")
-   ((dif +7 num) "[-@@][@@-@@@]")
-   ((dif +8 num) "[-@@][@-@@@@]")
-   ((dif +9 num) "[-@@][-@@@@@]")))
+   ((diff +0 num) "[@-@][@@@@-@]")
+   ((diff +1 num) "[@-@][@@@-@@]")
+   ((diff +2 num) "[@-@][@@-@@@]")
+   ((diff +3 num) "[@-@][@-@@@@]")
+   ((diff +4 num) "[@-@][-@@@@@]")
+   ((diff +5 num) "[-@@][@@@@-@]")
+   ((diff +6 num) "[-@@][@@@-@@]")
+   ((diff +7 num) "[-@@][@@-@@@]")
+   ((diff +8 num) "[-@@][@-@@@@]")
+   ((diff +9 num) "[-@@][-@@@@@]")))
 
 (defun number-to-air-rod (num)
   (fill
-   ((dif +0 num) "[@-@@@@][@-@]")
-   ((dif +1 num) "[@@-@@@][@-@]")
-   ((dif +2 num) "[@@@-@@][@-@]")
-   ((dif +3 num) "[@@@@-@][@-@]")
-   ((dif +4 num) "[@@@@@-][@-@]")
-   ((dif +5 num) "[@-@@@@][@@-]")
-   ((dif +6 num) "[@@-@@@][@@-]")
-   ((dif +7 num) "[@@@-@@][@@-]")
-   ((dif +8 num) "[@@@@-@][@@-]")
-   ((dif +9 num) "[@@@@@-][@@-]")))
+   ((diff +0 num) "[@-@@@@][@-@]")
+   ((diff +1 num) "[@@-@@@][@-@]")
+   ((diff +2 num) "[@@@-@@][@-@]")
+   ((diff +3 num) "[@@@@-@][@-@]")
+   ((diff +4 num) "[@@@@@-][@-@]")
+   ((diff +5 num) "[@-@@@@][@@-]")
+   ((diff +6 num) "[@@-@@@][@@-]")
+   ((diff +7 num) "[@@@-@@][@@-]")
+   ((diff +8 num) "[@@@@-@][@@-]")
+   ((diff +9 num) "[@@@@@-][@@-]")))
 
 ;; main
 (defun main ()
diff --git a/examples/abacus/writing.lali b/examples/abacus/writing.lali
index 17fd7c4..4876582 100755
--- a/examples/abacus/writing.lali
+++ b/examples/abacus/writing.lali
@@ -4,47 +4,47 @@
 ;; functions
 (defun random-number (cases)
   (fill
-   ((dif cases +0) (cons (random +9) ()))
+   ((diff cases +0) (cons (random +9) ()))
    (f (cons (random +9) (random-number (- cases +1))))))
 
 (defun number-to-symbol (num)
   (fill
-   ((dif +0 num) '0)
-   ((dif +1 num) '1)
-   ((dif +2 num) '2)
-   ((dif +3 num) '3)
-   ((dif +4 num) '4)
-   ((dif +5 num) '5)
-   ((dif +6 num) '6)
-   ((dif +7 num) '7)
-   ((dif +8 num) '8)
-   ((dif +9 num) '9)))
+   ((diff +0 num) '0)
+   ((diff +1 num) '1)
+   ((diff +2 num) '2)
+   ((diff +3 num) '3)
+   ((diff +4 num) '4)
+   ((diff +5 num) '5)
+   ((diff +6 num) '6)
+   ((diff +7 num) '7)
+   ((diff +8 num) '8)
+   ((diff +9 num) '9)))
 
 (defun number-to-earth-rod (num)
   (fill
-   ((dif +0 num) "[@-@][@@@@-@]")
-   ((dif +1 num) "[@-@][@@@-@@]")
-   ((dif +2 num) "[@-@][@@-@@@]")
-   ((dif +3 num) "[@-@][@-@@@@]")
-   ((dif +4 num) "[@-@][-@@@@@]")
-   ((dif +5 num) "[-@@][@@@@-@]")
-   ((dif +6 num) "[-@@][@@@-@@]")
-   ((dif +7 num) "[-@@][@@-@@@]")
-   ((dif +8 num) "[-@@][@-@@@@]")
-   ((dif +9 num) "[-@@][-@@@@@]")))
+   ((diff +0 num) "[@-@][@@@@-@]")
+   ((diff +1 num) "[@-@][@@@-@@]")
+   ((diff +2 num) "[@-@][@@-@@@]")
+   ((diff +3 num) "[@-@][@-@@@@]")
+   ((diff +4 num) "[@-@][-@@@@@]")
+   ((diff +5 num) "[-@@][@@@@-@]")
+   ((diff +6 num) "[-@@][@@@-@@]")
+   ((diff +7 num) "[-@@][@@-@@@]")
+   ((diff +8 num) "[-@@][@-@@@@]")
+   ((diff +9 num) "[-@@][-@@@@@]")))
 
 (defun number-to-air-rod (num)
   (fill
-   ((dif +0 num) "[@-@@@@][@-@]")
-   ((dif +1 num) "[@@-@@@][@-@]")
-   ((dif +2 num) "[@@@-@@][@-@]")
-   ((dif +3 num) "[@@@@-@][@-@]")
-   ((dif +4 num) "[@@@@@-][@-@]")
-   ((dif +5 num) "[@-@@@@][@@-]")
-   ((dif +6 num) "[@@-@@@][@@-]")
-   ((dif +7 num) "[@@@-@@][@@-]")
-   ((dif +8 num) "[@@@@-@][@@-]")
-   ((dif +9 num) "[@@@@@-][@@-]")))
+   ((diff +0 num) "[@-@@@@][@-@]")
+   ((diff +1 num) "[@@-@@@][@-@]")
+   ((diff +2 num) "[@@@-@@][@-@]")
+   ((diff +3 num) "[@@@@-@][@-@]")
+   ((diff +4 num) "[@@@@@-][@-@]")
+   ((diff +5 num) "[@-@@@@][@@-]")
+   ((diff +6 num) "[@@-@@@][@@-]")
+   ((diff +7 num) "[@@@-@@][@@-]")
+   ((diff +8 num) "[@@@@-@][@@-]")
+   ((diff +9 num) "[@@@@@-][@@-]")))
 
 ;; main
 (defun main ()
diff --git a/examples/hanoi.lali b/examples/hanoi.lali
index 59e3d10..786633c 100644
--- a/examples/hanoi.lali
+++ b/examples/hanoi.lali
@@ -7,7 +7,7 @@
   (newline))
 
 (defun hanoi-move (num from to via)
-  (fill ((dif num +1)
+  (fill ((diff num +1)
          (hanoi-print num from to))
         (f
          (prog
diff --git a/examples/mandelbrot.lali b/examples/mandelbrot.lali
index c07b07d..0268deb 100644
--- a/examples/mandelbrot.lali
+++ b/examples/mandelbrot.lali
@@ -6,7 +6,7 @@
         "2" "3" "4" "5" "6" "7" "8" "9" "%" "*" "&" "$" "@" "#"))
 
 (defun mandelbrot-iter (x y x0 y0 i)
-  (fill ((dif i +28) " ")
+  (fill ((diff i +28) " ")
         ((not (> (+ (* x0 x0) (* y0 y0)) +4)) (nth i mandelbrot-chars))
         (f (mandelbrot-iter x y
                             (+ (- (* x0 x0) (* y0 y0)) x) (+ (* +2 x0 y0) y)
diff --git a/examples/speech/en-random.lali b/examples/speech/en-random.lali
index 9ac271d..9deb0b0 100755
--- a/examples/speech/en-random.lali
+++ b/examples/speech/en-random.lali
@@ -23,13 +23,13 @@
 
 (defun assoc (el lst)
   (fill
-   ((dif el (car (car lst))) (car lst))
+   ((diff el (car (car lst))) (car lst))
    ((algo lst) '(f f))
    (f (assoc el (cdr lst)))))
 
 (defun without (el lst)
   (fill
-   ((dif el (car lst)) f)
+   ((diff el (car lst)) f)
    ((algo (car lst)) t)
    (f (without el (cdr lst)))))
 
@@ -76,7 +76,7 @@
 
    (set 'question-score target-question)
    (set 'my-words (readl))
-   (differ my-words '(f))
+   (diff my-words '(f))
    (set 'answer-score (get-answer-score
                        (map
                         (lambda (word)
@@ -85,7 +85,7 @@
    (princ "\n~")
    (newline)
    (fill
-    ((dif target-answer
+    ((diff target-answer
           (+ question-score answer-score))
      'correct)
     (f 'wrong))))
@@ -93,8 +93,8 @@
 (defun loop ()
   (set 'res (main))
   (fill
-   ((dif res 'correct) (loop))
-   ((dif res 'wrong) (prog (princ ">> wrong") (newline)))
+   ((diff res 'correct) (loop))
+   ((diff res 'wrong) (prog (princ ">> wrong") (newline)))
    (f f)))
 
 
diff --git a/examples/speech/en-random_more.lali b/examples/speech/en-random_more.lali
index fd94c6e..63c63c2 100755
--- a/examples/speech/en-random_more.lali
+++ b/examples/speech/en-random_more.lali
@@ -37,13 +37,13 @@
 
 (defun assoc (el lst)
   (fill
-   ((dif el (car (car lst))) (car lst))
+   ((diff el (car (car lst))) (car lst))
    ((algo lst) '(f f))
    (f (assoc el (cdr lst)))))
 
 (defun without (el lst)
   (fill
-   ((dif el (car lst)) f)
+   ((diff el (car lst)) f)
    ((algo (car lst)) t)
    (f (without el (cdr lst)))))
 
@@ -102,7 +102,7 @@
 
    (set 'question-score target-question)
    (set 'my-words (readl))
-   (differ my-words '(f))
+   (diff my-words '(f))
    (set 'answer-score (get-answer-score
                        (map
                         (lambda (word)
@@ -111,7 +111,7 @@
    (princ "\n~")
    (newline)
    (fill
-    ((dif target-answer
+    ((diff target-answer
           (+ question-score answer-score))
      'correct)
     (f 'wrong))))
@@ -119,8 +119,8 @@
 (defun loop ()
   (set 'res (main))
   (fill
-   ((dif res 'correct) (loop))
-   ((dif res 'wrong) (prog (princ ">> wrong") (newline)))
+   ((diff res 'correct) (loop))
+   ((diff res 'wrong) (prog (princ ">> wrong") (newline)))
    (f f)))
 
 
diff --git a/examples/speech/pt-fixed_answer.lali b/examples/speech/pt-fixed_answer.lali
index 0002672..b500975 100755
--- a/examples/speech/pt-fixed_answer.lali
+++ b/examples/speech/pt-fixed_answer.lali
@@ -18,13 +18,13 @@
 
 (defun assoc (el lst)
   (fill
-   ((dif el (car (car lst))) (car lst))
+   ((diff el (car (car lst))) (car lst))
    ((algo lst) '(f f))
    (f (assoc el (cdr lst)))))
 
 (defun without (el lst)
   (fill
-   ((dif el (car lst)) f)
+   ((diff el (car lst)) f)
    ((algo (car lst)) t)
    (f (without el (cdr lst)))))
 
@@ -72,14 +72,14 @@
 
    (set 'question-score target-question)
    (set 'my-reply (readl))
-   (differ my-reply '(f))
+   (diff my-reply '(f))
    (set 'answer-score (get-answer-score
                        (map
                         (lambda (word)
                           (car (cdr (assoc word reply))))
                         my-reply)))
    (fill
-    ((dif target-answer
+    ((diff target-answer
           (+ question-score answer-score))
      'correct)
     (f 'wrong))))
@@ -87,8 +87,8 @@
 (defun loop ()
   (set 'res (main))
   (fill
-   ((dif res 'correct) (loop))
-   ((dif res 'wrong) (prog (princ ">> errado") (newline)))
+   ((diff res 'correct) (loop))
+   ((diff res 'wrong) (prog (princ ">> errado") (newline)))
    (f f)))
 
 (loop)
diff --git a/examples/speech/pt-identify.lali b/examples/speech/pt-identify.lali
index bef74ef..7dd69b6 100755
--- a/examples/speech/pt-identify.lali
+++ b/examples/speech/pt-identify.lali
@@ -12,7 +12,7 @@
 
 (defun assoc (number lst)
   (fill
-   ((dif number (car (car lst))) (car lst))
+   ((diff number (car (car lst))) (car lst))
    ((algo lst) f)
    (f (assoc number (cdr lst)))))
 
@@ -35,7 +35,7 @@
    (set 'it-quest (assoc target-question question))
    (princ (car (cdr it-quest)))
    (princ "\b?")
-   (not (dif (read) (car (cdr (cdr it-quest)))))))
+   (not (diff (read) (car (cdr (cdr it-quest)))))))
 
 (defun loop ()
   (fill
diff --git a/examples/speech/pt-random.lali b/examples/speech/pt-random.lali
index e038f68..5454dc1 100755
--- a/examples/speech/pt-random.lali
+++ b/examples/speech/pt-random.lali
@@ -25,13 +25,13 @@
 
 (defun assoc (el lst)
   (fill
-   ((dif el (car (car lst))) (car lst))
+   ((diff el (car (car lst))) (car lst))
    ((algo lst) '(f f f))
    (f (assoc el (cdr lst)))))
 
 (defun without (el lst)
   (fill
-   ((dif el (car lst)) f)
+   ((diff el (car lst)) f)
    ((algo (car lst)) t)
    (f (without el (cdr lst)))))
 
@@ -83,7 +83,7 @@
 
    (set 'question-score target-question)
    (set 'my-words (readl))
-   (differ my-words '(f))
+   (diff my-words '(f))
    (set 'answer-score (get-answer-score
                        (map
                         (lambda (word)
@@ -92,7 +92,7 @@
    (princ "\n~")
    (newline)
    (fill
-    ((dif target-answer
+    ((diff target-answer
           (+ question-score answer-score))
      'correct)
     (f 'wrong))))
@@ -100,8 +100,8 @@
 (defun loop ()
   (set 'res (main))
   (fill
-   ((dif res 'correct) (loop))
-   ((dif res 'wrong) (prog (princ ">> errado") (newline)))
+   ((diff res 'correct) (loop))
+   ((diff res 'wrong) (prog (princ ">> errado") (newline)))
    (f f)))
 
 
diff --git a/examples/speech/pt-random_more.lali b/examples/speech/pt-random_more.lali
index 0c91c2c..94cd41c 100755
--- a/examples/speech/pt-random_more.lali
+++ b/examples/speech/pt-random_more.lali
@@ -37,13 +37,13 @@
 
 (defun assoc (el lst)
   (fill
-   ((dif el (car (car lst))) (car lst))
+   ((diff el (car (car lst))) (car lst))
    ((algo lst) '(f f))
    (f (assoc el (cdr lst)))))
 
 (defun without (el lst)
   (fill
-   ((dif el (car lst)) f)
+   ((diff el (car lst)) f)
    ((algo (car lst)) t)
    (f (without el (cdr lst)))))
 
@@ -102,7 +102,7 @@
 
    (set 'question-score target-question)
    (set 'my-words (readl))
-   (differ my-words '(f))
+   (diff my-words '(f))
    (set 'answer-score (get-answer-score
                        (map
                         (lambda (word)
@@ -111,7 +111,7 @@
    (princ "\n~")
    (newline)
    (fill
-    ((dif target-answer
+    ((diff target-answer
           (+ question-score answer-score))
      'correct)
     (f 'wrong))))
@@ -119,8 +119,8 @@
 (defun loop ()
   (set 'res (main))
   (fill
-   ((dif res 'correct) (loop))
-   ((dif res 'wrong) (prog (princ ">> errado") (newline)))
+   ((diff res 'correct) (loop))
+   ((diff res 'wrong) (prog (princ ">> errado") (newline)))
    (f f)))
 
 
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)
diff --git a/test/main.lali b/test/main.lali
index 5ad4b55..a63cef7 100644
--- a/test/main.lali
+++ b/test/main.lali
@@ -3,11 +3,11 @@
 (defun test (test-expr res)
   (newline)
   (princ
-   (list (fill ((differ (eval test-expr) res) '+)
+   (list (fill ((diff (eval test-expr) res) '+)
                ('f 'fail))
          '--> test-expr))
   (and success
-       (set 'success (fill ((differ (eval test-expr) res) t)
+       (set 'success (fill ((diff (eval test-expr) res) t)
                            (f f)))))
 
 ;; atom
@@ -17,23 +17,16 @@
 (test '(atom '(x a)) f)
 ;(test '(atom 'a) undef)
 
-;; dif
-(test '(dif () 'b) t)
-(test '(dif () ()) f)
-(test '(dif 'a 'b) t)
-(test '(dif 'a 'a) f)
-(test '(dif 'a '(b . c)) t)
-(test '(dif 'a '(b c)) t)
-(test '(dif '(b . c) '(b . c)) t)
-(test '(dif '(b c) '(b c)) t)
-
-;; differ
-(test '(differ 'a ()) t)
-(test '(differ () ()) f)
-(test '(differ 'a '(b c)) t)
-(test '(differ '(a b) '(b c)) t)
-(test '(differ '(b . c) '(b . c)) f)
-(test '(differ '(b c) '(b c)) f)
+;; diff
+(test '(diff 'a ()) t)
+(test '(diff () 'b) t)
+(test '(diff () ()) f)
+(test '(diff 'a 'b) t)
+(test '(diff 'a 'a) f)
+(test '(diff 'a '(b c)) t)
+(test '(diff '(a b) '(b c)) t)
+(test '(diff '(b . c) '(b . c)) f)
+(test '(diff '(b c) '(b c)) f)
 
 ;; car
 (test '(car ()) ())