Handle case where many parses an empty result

1 files changed, 6 insertions, 2 deletions

diff --git a/parser.lisp b/parser.lisp
index bfe2614..d22ae81 100644
--- a/parser.lisp
+++ b/parser.lisp
@@ -40,6 +40,10 @@
                     :message (format nil "Didn't reach expected limit: ~a." limit))
       (make-parsing :tree tree :left input))))
 
+(defun fail (message)
+  (lambda (input &key limit lazy)
+    (make-failure :place input :message message)))
+
 (defun bind (p f &key (greedy t))
   (lambda (input &key limit lazy)
     (let (r)
@@ -165,7 +169,7 @@
 (defun many (p)
   (comp ((x p)
          (xs (if (not x)
-               (error "Cannot define (many (optional x)). Use (optional (many x)) instead.")
+               (fail "Parsing result is empty.")
                (optional (many p)))))
         (cons x xs)))
 
@@ -191,7 +195,7 @@
   (comp ((v p)
          (sep (optional separator))
          (vn (if sep
-               (crit (separated-list p separator))
+               (separated-list p separator)
                nothing)))
         (if include-separator
           (cons v (cons sep vn))