Assumption of a callback-based, "event driven programming" library is too strong.

[enolan]

Hi Heinrich!

My tutorial has progressed quite a bit. My biggest gripe is how hard it is to do things that aren't hooking it up to wxHaskell or something similar to wxHaskell. I should not have had to write this:

addHandlerFromThread :: (Chan a -> IO ()) -> AddHandler a
addHandlerFromThread writerThread handler = do
    chan <- newChan
    tId1 <- forkIO (writerThread chan)
    tId2 <- forkIO $ forever $ (readChan chan >>= handler)
    return (killThread tId1 >> killThread tId2)

And what if I have a thread or group of threads that consume multiple inputs and/or produce multiple outputs? I think I need a lower level interface for that i.e. either you or me should write a more general system for hooking stuff up to FRP-land.

Regards,
Echo

[HeinrichApfelmus]

Nice to see your tutorial progressing!

But what alternative assumption should reactive-banana make about the "outside world"?

As I see it, FRP is essentially just a fancy way to write callback functions, i.e. things that can be passed to AddHandlers. I'm not very happy with the administrative mumbo-jumbo that is currently needed to hook events in and out of reactive-banana, but it's the simplest one I could come up with so far.

Since you are implementing a custom timer and hence a miniature event-based framework, it seems quite reasonable to me that you have to implement your own machinery with managing callbacks. Fortunately, reactive-banana can help a bit by providing the newAddHandler function.

[enolan]

As /I/ see it, FRP is a fancy way to talk about systems that progress over
time. See herehttp://www.reddit.com/r/haskell/comments/11ixcl/absurd_ambition_towards_lifting/
for
a rank n generalization idea. Maybe doing that actual work can be Kmett's
job, he seems to know what he's talking about.

On Tue, Oct 16, 2012 at 7:03 AM, Heinrich Apfelmus <notifications@github.com

wrote:

Nice to see your tutorial progressing!

But what alternative assumption should reactive-banana make about the
"outside world"?

As I see it, FRP is essentially just a fancy way to write callback
functions, i.e. things that can be passed to AddHandlers. I'm not very
happy with the administrative mumbo-jumbo that is currently needed to hook
events in and out of reactive-banana, but it's the simplest one I could
come up with so far.

Since you are implementing a custom timer and hence a miniature
event-based framework, it seems quite reasonable to me that you have to
implement your own machinery with managing callbacks. Fortunately,
reactive-banana can help a bit by providing the newAddHandler function.

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