Oh, I understand. For what it's worth, some implementations do have that as an extension, although I've personally never used it. See http://www.sbcl.org/manual

Oh, I understand. For what it's worth, some implementations do have that as an extension, although I've personally never used it. See http://www.sbcl.org/manual/#Extensible-Sequences http://www.sbcl.org/manual/#Extensible-Sequences.