Micro improvement in Bool.compute

misc/bool.ml

@@ -164,9 +164,10 @@ struct
       | True -> full
       | False -> empty
       | Split(_,x, p,i,n) ->
-	  let p = cap (atom x) (aux p)
+          let x1 = atom x in
+          let p = cap x1 (aux p)
           and i = aux i
-	  and n = diff (aux n) (atom x) in
+          and n = diff (aux n) x1 in
           cup (cup p i) n
     in
     aux b