Change "any" to "either" and add "nothing"

1 files changed, 17 insertions, 14 deletions

diff --git a/parser.lisp b/parser.lisp
index 16911ec..37abb75 100644
--- a/parser.lisp
+++ b/parser.lisp
@@ -29,16 +29,16 @@
   (lambda (input)
     (make-failure :place input :message message)))
 
-(defun any (first-parser &rest other-parsers)
+(defun either (first-parser &rest other-parsers)
   (lambda (input)
-    (labels ((any-rec (body)
-                      (if (cdr body)
-                        (let ((r (funcall (car body) input)))
-                          (if (parsing-p r)
-                            r
-                            (any-rec (cdr body))))
-                        (funcall (car body) input))))
-      (any-rec (cons first-parser other-parsers)))))
+    (labels ((either-rec (body)
+                         (if (cdr body)
+                           (let ((r (funcall (car body) input)))
+                             (if (parsing-p r)
+                               r
+                               (either-rec (cdr body))))
+                           (funcall (car body) input))))
+      (either-rec (cons first-parser other-parsers)))))
 
 (defun unit (&optional (predicate #'characterp))
   (lambda (input)
@@ -56,14 +56,17 @@
           (p (second (car bindings))))
       `(bind ,p (lambda (,v) (comp ,(cdr bindings) ,@body))))))
 
+(defparameter nothing
+  (new nil))
+
 (defun zero-or-one (p)
-  (any p (new nil)))
+  (either p nothing))
 
 (defun zero-or-more (p)
-  (any (comp ((x p)
-              (xs (zero-or-more p)))
-         (cons x xs))
-       (new nil)))
+  (either (comp ((x p)
+                 (xs (zero-or-more p)))
+            (cons x xs))
+          nothing))
 
 (defun one-or-more (p)
   (comp ((x p)