Fri May 20 15:19:53 UTC 2005  mantoniotti
  * Fixed two major bugs reported by Norman Werver.  Unification of
  Fixed two major bugs reported by Norman Werver.  Unification of
  strings and symbols and of numers and symbols was not recurring on
  VAR-UNIFY, as required; thus
  
  	(unify '(?x ?x) '("asd" "qweert"))
  and
  	(unify '(foo ?x baz) '(foo 42 ?x))
  
  would succed.
  The two cases are now fixed.
  
diff -rN -u old-cl-unification-1/unifier.lisp new-cl-unification-1/unifier.lisp
--- old-cl-unification-1/unifier.lisp	2013-07-24 17:40:21.000000000 +0000
+++ new-cl-unification-1/unifier.lisp	2013-07-24 17:40:21.000000000 +0000
@@ -94,15 +94,15 @@
 
 (defmethod unify ((a symbol) (b string) &optional (env (make-empty-environment)))
   (cond ((variable-any-p a) env)
-        ((variablep a) (extend-environment a b env))
+        ((variablep a) (var-unify a b env))
         (t (error 'unification-failure
-             :format-control "Cannot unify a symbol with a string: ~S ~S."
-             :format-arguments (list a b)))))
+		  :format-control "Cannot unify a symbol with a string: ~S ~S."
+		  :format-arguments (list a b)))))
 
 
 (defmethod unify ((b string) (a symbol) &optional (env (make-empty-environment)))
   (cond ((variable-any-p a) env)
-        ((variablep a) (extend-environment a b env))
+        ((variablep a) (var-unify a b env))
         (t (error 'unification-failure
                   :format-control "Cannot unify a string with a symbol: ~S ~S."
                   :format-arguments (list b a)))))
@@ -121,13 +121,13 @@
 
 (defmethod unify ((a symbol) (b t) &optional (env (make-empty-environment)))
   (cond ((variable-any-p a) env)
-        ((variablep a) (extend-environment a b env))
+        ((variablep a) (var-unify a b env))
         (t (call-next-method))))
 
 
 (defmethod unify ((b t) (a symbol) &optional (env (make-empty-environment)))
   (cond ((variable-any-p a) env)
-        ((variablep a) (extend-environment a b env))
+        ((variablep a) (var-unify a b env))
         (t (call-next-method))))