fix for `slicef-at`

list.rkt

@@ -11,13 +11,14 @@
 
 (define+provide/contract (slicef-at xs pred [force? #f])
   ((list? procedure?) (boolean?) . ->* . list-of-lists?)
-  (define-values (last-list list-of-lists)
+  (define-values (last-list list-of-lists _)
-    (for/fold ([current-list empty][list-of-lists empty])([x (in-list xs)])
+    (for/fold ([current-list empty][list-of-lists empty][previous-x-was-pred #f])([x (in-list xs)])
-      (if (pred x)
+      (define pred-x (pred x))
+      (if (and (not previous-x-was-pred) pred-x)
           (values (cons x null) (if (not (empty? current-list))
                                     (cons (reverse current-list) list-of-lists)
-                                    list-of-lists))
+                                    list-of-lists) pred-x)
-          (values (cons x current-list) list-of-lists))))
+          (values (cons x current-list) list-of-lists pred-x))))
   (let ([list-of-lists (reverse (if (empty? last-list)
                                     list-of-lists
                                     (cons (reverse last-list) list-of-lists)))])

tests.rkt

@@ -157,6 +157,7 @@
 (check-equal? (slicef-at (range 5) procedure?) '((0 1 2 3 4)))
 (check-exn exn:fail:contract? (λ() (slicef-at (range 5) 3)))
 
+(check-equal? (slicef-at '(1 2) integer?) '((1 2)))
 
 (check-equal? (sublist (range 5) 0 0) '())
 (check-equal? (sublist (range 5) 0 1) '(0))