Hi, (This is the next episode of the "let's free scsh" saga.) I wish to get your opinions on the case of the reference implementations in the SRFI's. An SRFI, Scheme Request For Implementation, is the process by which the Scheme community agrees on standard libraries and features for various scheme implementations. Every SRFI contains a reference implementation, and bears this copyright notice: Copyright (C) /author/ (/year/). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Scheme Request For Implementation process or editors, except as needed for the purpose of developing SRFIs in which case the procedures for copyrights defined in the SRFI process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the authors or their successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE AUTHOR AND THE SRFI EDITORS DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. For an example, see http://srfi.schemers.org/srfi-19/srfi-19.html http://srfi.schemers.org/srfi-19/srfi-19.scm The question is: Is a scheme implementation that includes the reference implementation DFSG-free (providing the rest of the implementation is, obviously)? The SRFI FAQ, at http://srfi.schemers.org/srfi-faq.html, says: Does the SRFI copyright permit using a SRFI sample implementation (or a derivative of one) in my Scheme implementation? Yes. Does the SRFI copyright permit using parts of a SRFI in the documentation of my Scheme implementation? Yes. Doesn't the SRFI copyright notice contradict itself? You're probably thinking of the sentence "However, this document itself may not be modified in any way [...] except as needed for the purpose of developing SRFIs [...]" which might seem to contradict the answers to the previous questions. However, this sentence is only to prevent passing off a modified copy of the document as the document itself. So SRFI x is an inviolable entity (and once finalized, very close to cast in amber). But you can excerpt from it at will, with attribution. (We have actually consulted with several lawyers on this; it is what we intended, and it is what it means.) In the case of scsh, which includes some of these reference implementations, upstream's opinion is that what the license means is "the copyright needs to remain intact", not "the code cannot change". You can see the thread at: http://thread.gmane.org/gmane.lisp.scheme.scsh/1483 In particular the end of these mails: http://article.gmane.org/gmane.lisp.scheme.scsh/1495 http://article.gmane.org/gmane.lisp.scheme.scsh/1615 http://article.gmane.org/gmane.lisp.scheme.scsh/1618 Thank you for your time, -- Lionel
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