frp | 易学教程

How to implement reactive-banana behaviors that recursively depend on themself?

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问题 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

Reset timeout on event with RxJS

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I'm experimenting with RxJS (with the JQuery extension) and I'm trying to solve the following use case: Given that I have two buttons (A & B) I'd like to print a message if a certain "secret combination" is clicked within a given timeframe. For example the "secret combination" could be to click "ABBABA" within 5 seconds. If the combination is not entered within 5 seconds a timeout message should be displayed. This is what I currently have: var secretCombination = "ABBABA"; var buttonA = $("#button-a").clickAsObservable().map(function () { return "A"; }); var buttonB = $("#button-b")

frp 配置多个 web 项目，无需购买域名 (访问内网可视化界面，jupyter noterbook, visdom, tensorboard)

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frp 配置多个 web 项目，无需购买域名简单配置，参考前言：网上也有很多教程包括官方文档，都需要购买域名，并且把 frpc.ini 中 [web]节配置的 custom_domains 的值解析到外网的服务器，多个web项目需要多个 custom_domains（每个web项目保证唯一）,统统把这些 custom_domains 解析到外网服务器，然后就可以使用，使用方式就是 custom_domains:vhost_http_port，就可以实现多个web项目的访问。下面的方法不需要购买域名和域名解析服务，也可以实现多个web项目内网穿透使用提出解决方法依据的原理（想快速解决问题，请跳过）疑问： frp软件尽管配置了 custom_domains，但是统统解析到了同一台外网服务器，那为什么可以实现请求统一端口(frps.ini common 中的 vhost_http_port ) 来达到访问不同web项目的需求呢？ 1. 首先，我们都知道浏览器输入一个 url 的访问过程，如果是使用域名访问，那么首先需要解析域名获得真实的IP地址然后，通过TCP报文来发送。那么神奇的地方就来了，我们在 frpc.ini 中把所有的 web 项目的 custom_domains 都解析到了同一个 IP地址，并且 frps.ini 提供web访问的端口只有一个(vhost

Dynamic Elements based on Behaviour in threepenny-gui

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问题 To put it simple, I am looking for a way to display a Behaviour (UI Element) . My actual use-case is displaying a table, which can be filtered. So I have a function tableElement :: String -> UI Element (the String parameter being the filter condition) and an input field filterElement :: Element , which represents the filter. The most natural way for me to combine these would be something like this: bFilter <- stepper "" (valueChange filterElement) displaySomehow (fmap tableElement bFilter)

Fighting with FRP

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问题 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.

Convert from arrow notation

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问题 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

Execute MonadIO action inside of reactimate

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In reactive-banana, I am trying to run reactimate :: Event (IO ()) -> Moment () with some actions of Arduino in hArduino package , an instance of MonadIO . There seems no function of Arduino a -> IO a provided in the package. How would you execute Arduino actions in reactimate ? How would you execute Arduino actions in reactimate ? I would cause them to be executed indirectly, by executing an IO action which has an observable side-effect. Then, inside withArduino , I would observe this side-effect and run the corresponding Arduino command. Here's some example code. First, let's get the imports

reactive-banana throttling events

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I would like to implement a certain type of throttling of events in reactive-banana. It should work such that an event is not let through if arrives at less then delta seconds from the last event that passed through. If it is not let through then it is stored and is fired after delta seconds from the last fired event. Below is a program that implements this for lists of time stamped numbers. Would it be possible to translate this to reactive-banana ? Also, in reactive-banana how do I fire an event x seconds after some other event comes in ? module Main where import Data.List -- 1 second

Testing in reactive-banana

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问题 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

reactive-banana: Firing event that contain the most up to date value of a Behavior

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问题 Suppose I have an event trigger which I want to do two things when fired. First, I want it to update the value of some behavior . Second, if other conditions are met, I want it to fire another event send_off with the updated value of the behavior. Expressed in code form, suppose I have trigger :: Event b trigger = ... updateFromTrigger :: b -> (a -> a) updateFromTrigger = ... conditionFromTrigger :: b -> Bool conditionFromTrigger = ... behavior :: Behavior a behavior = accumB initial_value