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@menu
-* Introduction:: About 8sync
+* Introduction::
+* Acknowledgements::
* Copying This Manual::
-* Index:: Complete index.
+* Index::
@end menu
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-
@node Introduction
@chapter Introduction
-8sync 8sync 8sync!
+8sync's goal is to make asynchronous programming easy. If you've worked
+with most other asynchronous programming environments, you know that it
+generally isn't. Usually asynchronous programming involves entering
+some sort of ``callback hell''. Some nicer environments like Asyncio
+for Python provide generator-based coroutines, but even these require a
+lot of work to carefully line up.
+
+Coding in 8sync, on the other hand, looks almost entirely like coding
+anywhere else. This is because 8sync makes great use of a cool feature
+in Guile called ``delimited continuations'' to power natural-feeling
+coroutines. Because of this, you can invoke your asynchronous code with
+a small wrapper around it, and that code will pop off to complete
+whatever other task it needs to do, and resume your function when it's
+ready passing back the appropriate value. (No need to manually chain
+the coroutines together, and no callback hell at all!)
+
+Now that's pretty cool!
+
+@node Acknowledgements
+@chapter Acknowledgements
+
+8sync has a number of inspirations:
+
+@itemize @bullet
+@item
+@uref{https://docs.python.org/3.5/library/asyncio.html, asyncio}
+for Python provides a nice asynchronous programming environment, and
+makes great use of generator-style coroutines. It's a bit more
+difficult to work with than 8sync (or so thinks the author) because you
+have to ``line up'' the coroutines.
+
+@item
+@uref{http://dthompson.us/pages/software/sly.html, Sly}
+by David Thompson is an awesome functional reactive game programming
+library for Guile. If you want to write graphical games, Sly is almost
+certainly a better choice than 8sync. Thanks to David for being very
+patient in explaining tough concepts; experience on hacking Sly greatly
+informed 8sync's development. (Check out Sly, it rocks!)
+
+@item
+Reading @uref{https://mitpress.mit.edu/sicp/, SICP}, particularly
+@uref{https://mitpress.mit.edu/sicp/full-text/book/book-Z-H-19.html#%_chap_3,
+ Chapter 3's writings on concurrent systems},
+greatly informed 8sync's design.
+
+@item
+Finally, @uref{https://docs.python.org/3.5/library/asyncio.html, XUDD}
+was an earlier ``research project'' that preceeded 8sync. It attempted
+to bring an actor model system to Python. However, the author
+eventually grew frustrated with some of Python's limitations, fell in
+love with Guile, and well... now we have 8sync, which is much more
+general anyway.
+
+@end itemize
+
+The motivation to build 8sync came out of
+@uref{https://lists.gnu.org/archive/html/guile-devel/2015-10/msg00015.html, a conversation}
+at the FSF 30th party between Mark Weaver, David Thompson, Andrew
+Engelbrecht, and Christopher Allan Webber over how to build
+an asynchronous event loop for Guile and just what would be needed.
+
+A little over a month after that, hacking on 8sync began!
+
+
+@node 8sync's license and general comments on copyleft
+@chapter 8sync's license and general comments on copyleft
+
+8sync is released under the GNU LGPL (Lesser General Public License),
+version 3 or later, as published by the Free Software Foundation. The
+short version of this is that if you distribute a modifications to
+8sync, whether alone or in some larger combination, must release the
+corresponding source code. In general, it is best to contribute them
+back to 8sync under the same terms; we'd appreciate any enhancements or
+fixes to be contributed upstream to 8sync itself. (This is an
+intentional oversimplification for brevity, please read the LGPL for the
+precise terms.)
+
+This usage of the LGPL helps us ensure that 8sync and derivatives of
+8sync as a library will remain free. However, we cannot provide the
+same freedom-protecting requirements for applications built on top of
+8sync. Though it is not a requirement, we request you use 8sync to
+build free software rather than use it to contribute to the growing
+world of proprietary software.
+
+The choice of the LGPL for 8sync was a strategic one, though in general,
+we encourage stronger copyleft. (For more thinking on this position, see
+@uref{https://www.gnu.org/licenses/why-not-lgpl.html,
+ Why you shouldn't use the Lesser GPL for your next library}.)
+
+In particular, if you are building a library or application that uses
+8sync in some useful way, consider releasing your program under the GNU
+GPL or GNU AGPL! In a world where more and more software is locked
+down, where software is used to restrict users, we could use every
+chance we can get to provide protections so that software which is free
+remains free, and encourages even more software freedom to be built upon
+it.
+
+So to answer the question, ``Can I build a proprietary program on top of
+8sync?'' our response is ``Yes, but please don't. Choose to release
+your software under a freedom-respecting license. And help us turn the
+tide towards greater software freedom... consider a strong copyleft
+license!''
@node Copying This Manual
projects / 8sync.git / blobdiff