<PRIVATE
-: ,, ( obj -- ) building get peek push ;
+: ,, ( obj -- ) building get last push ;
: v, ( -- ) V{ } clone , ;
-: ,v ( -- ) building get dup peek empty? [ dup pop* ] when drop ;
+: ,v ( -- ) building get dup last empty? [ dup pop* ] when drop ;
: (monotonic-split) ( seq quot -- newseq )
[