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,
--
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