Modify: >> checks failure check syntax

1 files changed, 4 insertions, 0 deletions

diff --git a/hyperquirks.lisp b/hyperquirks.lisp
index 27051c5..d64ce08 100644
--- a/hyperquirks.lisp
+++ b/hyperquirks.lisp
@@ -203,6 +203,10 @@ single pipe form."
               ()
               "Invalid pipe form: ~s"
               (find-if-not #'pipe-form-p pipe-forms))
+      (assert (loop :for (f1 f2) :on pipe-forms
+                    :always (or (not (eql :? f1)) (and f2 (not (eql :? f2)))))
+              ()
+              "Failure checks :? must always be followed by a valid form.")
 
       (list 'block block
             (reduce #'folder (escape-early-transform pipe-forms) :initial-value initform)))))