diff --git a/basis/dlists/dlists.factor b/basis/dlists/dlists.factor index bbac957aa2..758b704708 100644 --- a/basis/dlists/dlists.factor +++ b/basis/dlists/dlists.factor @@ -6,13 +6,7 @@ deques fry hashtables kernel parser search-deques sequences summary vocabs.loader ; IN: dlists -MIXIN: ?dlist-node - -INSTANCE: f ?dlist-node - -TUPLE: dlist-link { prev ?dlist-node } { next ?dlist-node } ; - -INSTANCE: dlist-link ?dlist-node +TUPLE: dlist-link { prev maybe: dlist-link } { next maybe: dlist-link } ; TUPLE: dlist-node < dlist-link obj ; @@ -28,8 +22,8 @@ M: dlist-link obj>> ; \ dlist-node new-dlist-link ; inline TUPLE: dlist -{ front ?dlist-node } -{ back ?dlist-node } ; +{ front maybe: dlist-link } +{ back maybe: dlist-link } ; : ( -- list ) dlist new ; inline