: cut-slice* ( seq n -- before after )
[ head-slice* ] [ tail-slice* ] 2bi ;
-: ?<slice> ( from to/f sequence -- slice )
- over [ nip [ length ] [ ] bi ] unless <slice> ; inline
+: ?<slice> ( from/f to/f sequence -- slice )
+ [ [ 0 ] unless* ] 2dip
+ over [ nip [ length ] [ ] bi ] unless
+ <slice> ; inline
: sequence>slice ( sequence -- slice )
[ drop 0 ] [ length ] [ ] tri <slice> ; inline