anchor.diff:  ;;;;AUTHORS
   ;;;;    <PJB> Pascal J. Bourguignon <pjb@informatimago.com>
   ;;;;MODIFICATIONS
  +;;;;    2020-03-01 <PJB> Optimized CONTENTS-FROM-STREAM (avoid adjust-array when reading a whole file).
   ;;;;    2007-07-07 <PJB> Added CONTENTS-FROM-STREAM.
   ;;;;    2005-03-17 <PJB> Added COPY-OVER.
   ;;;;    2004-09-12 <PJB> Removed use of GRAY streams,
  
positive.code: ;;;;LEGAL
  ;;;;    AGPL3
  ;;;;
  ;;;;    Copyright Pascal J. Bourguignon 2004 - 2016
  ;;;;
  ;;;;    This program is free software: you can redistribute it and/or modify
  ;;;;    it under the terms of the GNU Affero General Public License as published by
  
negative.code:                 :do (vector-push-extend byte buffer))
                (return-from contents-from-stream buffer)))
          ;; normal case:
          (let* ((busize (or length (setf length (ignore-errors (file-length stream))) min-size))
                 (eltype (stream-element-type stream))
                 (initel (if (subtypep eltype 'integer) 0 #\space))
                 (buffer (make-array busize
  