QUALIFIED: sets
QUALIFIED: classes

SYMBOL: +shadowed+

: (assoc-slots) ( slots... length seq -- assoc ) 
    [ narray reverse! ] dip swap zip ; inline

: (assoc-slots-to-initial) ( seq class -- assoc ) 
    initial-values reverse! zip ;

: (extract-slot-values) ( initial-slot-assoc slot-assoc length -- slots... )
    [ assoc-union! reverse! [ last ] map ] dip firstn ; inline

MACRO: shadowed-boa ( class -- tuple ) 
    [
        all-slots [ name>> ] map 
        [ reverse! sets:members ] keep
        [ [ length ] bi@ ] 2keep swapd
    ] keep
   '[ _ _ (assoc-slots) _ _ _
        [ (assoc-slots-to-initial) -rot (extract-slot-values) ] 
        [ boa ] bi 
    ] ;

: mark-shadowed-slots ( tuple -- marked )
    +shadowed+ over dup classes:class all-slots dup
    [ name>> ] map duplicates sets:members
    [  '[ name>> _ = ] filter but-last
      [ offset>> set-slot ] 2 nwith each
    ] 3 nwith each  ;