frp

I have a Behavior whose value I want to change based on the occurrence of an Event and the Behavior's current value. In the example below I have two counters that are updated based on whether a boolean behaviour is True or False. As it is this code crashes with a <<loop>> exception, but I'm unsure how to restructure it to work or how else to approach this problem. {-# LANGUAGE ScopedTypeVariables #-} import Reactive.Banana import Reactive.Banana.Frameworks import Control.Arrow import Control.Concurrent import Control.Monad import Control.Monad.Fix counter :: Bool -> Event t Int -> Behavior t

I've read about FRP and was very excited. It looks great, so you can write more high-level code, and everything is more composable, and etc. Then I've tried to rewrite my own little game with a few hundreds sloc from plain js to Bacon. And I found that instead of writing high-level logic-only code, I actually beating with Bacon.js and its adherence to principles. I run into some headache that mostly interfere clean code .take(1) Instead of getting value, I should create ugly constructions. Circular dependencies Sometimes they should be by logic. But implementing it in FRP is scary Active state

I'm still trying to get a hang of the parallels between arrow notation and the semantics of the Arrow typeclasses defined in Haskell. In particular, this question seems to have a very canonical example of a small counter written with arrow notation: counter :: ArrowCircuit a => a Bool Int counter = proc reset -> do rec output <- returnA -< if reset then 0 else next next <- delay 0 -< output+1 returnA -< output Can someone show me how to convert this back into Haskell2010 without arrow notation? {- | +---------+ >Bool>--------------> | | >------------------>Int> +---------+ | arr f | /---->

I'm getting started with Netwire version 5. I have no problem writing all the wires I want to transform my inputs into my outputs. Now the time has come to write the IO wrapper to tie in my real-world inputs, and I am a bit confused. Am I supposed to create a custom session type for the s parameter of Wire s e m a b and embed my sensor values in there? If so, I have these questions: What's up with the Monoid s context of class (Monoid s, Real t) => HasTime t s | s -> t ? What is it used for? I was thinking of tacking on a Map String Double with my sensor readings, but how should my monoid

There is some diagrams of Yampa switches at: http://www.haskell.org/haskellwiki/Yampa/switch http://www.haskell.org/haskellwiki/Yampa/rSwitch http://www.haskell.org/haskellwiki/Yampa/kSwitch (and so on). I've found that the switch , the only one diagram with description, is the easiest one to get understand. The others seems hard to follow the similar symbols to read the diagrams. For example, to try to read the rSwitch with the symbols used in the switch may be: Be a recursive SF which is always fed a signal of type 'in' and returns a signal of type 'out'. Start with an initial SF of the same

Is there a way to unit test networks created in reactive banana? Say I've built up some network with some input events - is it possible to verify that events have produced some output stream/behaviours have some value after some number of input events. Does it even make sense to do this? I noticed there are various interpret* functions but couldn't seem to work out how to use them. There's also the Model module which looks ideal for testing but has completely different types to the real implementation. When you say "unit test," I'm imagining something like QuickCheck , where you inject a