Remove unecessary slot from arrow models

basis/models/arrow/arrow.factor

@@ -1,18 +1,17 @@
 ! Copyright (C) 2008, 2009 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: accessors models kernel ;
+USING: accessors models kernel sequences ;
 IN: models.arrow
 
-TUPLE: arrow < model model quot ;
+TUPLE: arrow < model quot ;
 
 : <arrow> ( model quot -- arrow )
     f arrow new-model
         swap >>quot
-        over >>model
         [ add-dependency ] keep ;
 
 M: arrow model-changed
     [ [ value>> ] [ quot>> ] bi* call( old -- new ) ] [ nip ] 2bi
     set-model ;
 
-M: arrow model-activated [ model>> ] keep model-changed ;
+M: arrow model-activated [ dependencies>> ] keep [ model-changed ] curry each ;