[reactive] switching events = space leak?

[Don Vincenze]

Wow thank you for all these pointers ... I must take the time to look
into these libraries. Stuff like this doesn't come up when you Google
"Functional Reactive Programming" or at least doesn't rank very high.



I'm not sure I understand the sodium approach (couldn't find switch in
elerea). The aging/'trimming' approach in banana seems to rely on the
events being switched into being known from the start, i.e. the point
in time 'switch' starts executing. This way you can dynamically switch
into a static set of events but not dynamically into a dynamic set of
events.



In any case, considering such concerns seem to be transcend individual
libraries/frameworks, you wouldn't know of any mailing list/forum that
is more suitable for this discussion, i.e. a general FRP forum not tied
to any library or one purely focused on theory?





On Wed, Feb 6, 2013, at 07:22 PM, John Lato wrote:


This can be a serious issue, however most modern FRP implementations
(by which I mean at least reactive-banana, elerea, and sodium) have
solutions.  I'm sure elm does as well, but I don't have experience with
it.

I'm aware of two general approaches.  The first, used by elerea and
sodium, enforces that the creation of signaling and switching
constructs happen within a monad.  In this case the switching primitive
looks something like

mSwitch :: Behavior (SGen a) -> SGen (Behavior a)

this function is responsible for ensuring that signals and behaviors
are represented in the monad, and thus executed.

The other approach was introduced in Grapefruit, and to my knowledge is
only used in Grapefruit and reactive-banana.  Instead of a signal
generation monad, switchable constructs have an extra type parameter
that's used to enforce aging.  apfelmus has written a bit about it
at [1]http://apfelmus.nfshost.com/blog/2012/09/03-frp-dynamic-event-swi
tching-0-7.html .  Conceptually it's very similar to how the "st"
parameter is used in the ST monad if you're familiar with that.

as to scaling, it is possible for a reactive network to scale to fairly
large systems, but not all of them do.  I've been meaning to blog about
this soon, maybe over the next week or two.

John L.

References

1. http://apfelmus.nfshost.com/blog/2012/09/03-frp-dynamic-event-switching-0-7.html
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.haskell.org/pipermail/reactive/attachments/20130207/d4748a02/attachment.htm>