@titlepage
-@title 8sync 0.1
+@title 8sync
@subtitle Using 8sync, an asynchronous event loop for Guile
@author Christopher Allan Webber
@page
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.
+you know that it generally isn't.
Usually asynchronous programming involves entering some sort of
- ``callback hell''.
+`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.
+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.
+anywhere else.
This is because 8sync makes great use of a cool feature in Guile called
- ``delimited continuations'' to power natural-feeling coroutines.
+``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.
+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!)
+all!)
Now that's pretty cool!
@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.
+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.
+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.
+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.
+than 8sync.
Thanks to David for being very patient in explaining tough concepts;
- experience on hacking Sly greatly informed 8sync's development.
+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.
+@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.
+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.
+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.
+@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!
@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.
+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.
+8sync, whether alone or in some larger combination, must release the
+corresponding source code.
A program which uses this library, if distributed without source code,
- must also allow relinking with a modified version of this library.
+must also allow relinking with a modified version of this library.
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.
+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.)
+for the precise terms.)
This usage of the LGPL helps us ensure that 8sync and derivatives of
- 8sync as a library will remain free.
+8sync as a library will remain free.
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.
+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.
This is not a general recommendation to use the LGPL instead of the GPL
- for all libraries.
+for all libraries.
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}.)
+@uref{https://www.gnu.org/licenses/why-not-lgpl.html,
+ Why you shouldn't use the Lesser GPL for your next library}.)
Although 8sync provides some unique features, its main functionality is as
- an asynchronous event loop, and there are many other asynchronous event
- loop systems out there such as Node.js for Javascript and Asyncio for
- Python (there are others as well).
+an asynchronous event loop, and there are many other asynchronous event
+loop systems out there such as Node.js for Javascript and Asyncio for
+Python (there are others as well).
It is popular in some of these communities to hold anti-copyleft positions,
- which is unfortunate, and many community members seem to be adopting
- these positions because other developers they look up to are holding
- them.
+which is unfortunate, and many community members seem to be adopting
+these positions because other developers they look up to are holding
+them.
If you have come from one of these communities and are exploring 8sync, we
- hope reading this will help you reconsider your position.
+hope reading this will help you reconsider your position.
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!
+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.
+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!''
+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!''
\f
projects / 8sync.git / blobdiff