-: direct-head ( seq n -- seq' ) (head) direct-slice ; inline
-: direct-tail ( seq n -- seq' ) (tail) direct-slice ; inline
-: direct-head* ( seq n -- seq' ) from-end direct-head ; inline
-: direct-tail* ( seq n -- seq' ) from-end direct-tail ; inline
+: direct-head ( seq n -- seq' ) head-to-index direct-slice ; inline
+: direct-tail ( seq n -- seq' ) index-to-tail direct-slice ; inline
+: direct-head* ( seq n -- seq' ) from-tail direct-head ; inline
+: direct-tail* ( seq n -- seq' ) from-tail direct-tail ; inline