On Oct 7, 2012, at 16:59 , Stas Boukarev <stassats at gmail.com> wrote: > Taoufik Dachraoui <dachraoui.taoufik at gmail.com> writes: > >> Hi >> >> how to check that a sequence is null without using length? > (alexandria:sequence-of-length-p sequence 0) Or just (defun is-null-vector (v) (and (vectorp v) (zerop (first (array-dimensions v)))))