: reduce-from ( ... seq identity quot: ( ... prev elt -- ... next ) i -- ... result )
[ swap ] 2dip each-from ; inline
+: 2reduce-from ( ... seq1 seq2 identity quot: ( ... prev elt1 elt2 -- ... next ) i -- ... result )
+ [ -rot ] 2dip 2each-from ; inline
+
:: subseq* ( from to seq -- subseq )
seq length :> len
from [ dup 0 < [ len + ] when ] [ 0 ] if*