Add unset-rule.HEADmaster

2 files changed, 6 insertions, 0 deletions

diff --git a/src/l-system.lisp b/src/l-system.lisp
index 2f39259..01e2a1d 100644
--- a/src/l-system.lisp
+++ b/src/l-system.lisp
@@ -42,3 +42,8 @@ It can expand to parametric grammar or to context sensitive grammar."
          #'(lambda ,(append vars '(&rest rest))
              (declare (ignorable rest))
              ,@body)))
+
+(defun unset-rule (symbol)
+  "Unset rules from grammar."
+  (setf (gethash symbol *l-system-clauses*)
+        nil))
diff --git a/src/package.lisp b/src/package.lisp
index c2c3fb4..7b7dbfe 100644
--- a/src/package.lisp
+++ b/src/package.lisp
@@ -4,5 +4,6 @@
   (:use #:cl #:iter)
   (:export #:l-system
   	   #:->
+           #:unset-rule
 	   #:parametric-grammar
 	   #:context-sensitive-grammar))