boolean-expr: shorten some code

diff --git a/extra/boolean-expr/boolean-expr.factor b/extra/boolean-expr/boolean-expr.factor
index b35cd447398c5226137b41ef4fe5c9dfe29fc3b8..46449d74868d9f86fd86d08b7062dd061db43b57 100644 (file)
--- a/extra/boolean-expr/boolean-expr.factor
+++ b/extra/boolean-expr/boolean-expr.factor
@@ -67,7 +67,7 @@ METHOD: satisfiable? { ⊥ } drop f ;
 
 ! See if there is a term along with its negation in the conjunction seq.
 : (satisfiable?) ( seq -- ? )
-    [ \ ¬ instance? ] partition swap [ x>> ] map intersect empty? ;
+    [ ¬? ] partition swap [ x>> ] map intersect empty? ;
 
 METHOD: satisfiable? { □ }
     dnf [ (satisfiable?) ] any? ;