Re: Faster remove-duplicates with sorted list.

Joerg Mertens <joerg-mertens@t-online.de> wrote:

  (loop for element in list
        for last-element-key = nil then element-key
        for element-key = (funcall key element)
        for result = nil then (funcall test element-key last-element-key)
        unless result collect element))

This is clearer:

(defun uniquify-sorted-list (list &key (key #'identity) (test #'eql))
  (loop for element in list
        for element-key = (funcall key element)
            and last-element-key = nil then element-key
        for result = nil then (funcall test element-key last-element-key)
        unless result collect element))

I forgot that the loop way to step two clauses in parallel is to
combine them with an `and´.