New subject: Feedback on my first Reactive program: Monad Laws

29 Mar 2009

      Digging around with the commented query -- that a "pure (string)" is getting
delayed -- I've hit a rather fundamental problem: it seems Event doesn't
obey the Monad laws.  I don't know whether this is a known issue or whether
I'm being plain stupid, but this:--

module Main
    where

import FRP.Reactive
import FRP.Reactive.LegacyAdapters
import Control.Concurrent
import Control.Applicative
import Control.Monad
import Data.Monoid
import Data.Maybe

main = do
        clock        <- makeClock
        (sink, evnt) <- makeEvent clock
        forkIO . sequence_ $ repeat (getLine >>= sink)
        adaptE . fmap putStrLn $ (pure "A Line!" `mappend` evnt)
--     adaptE . fmap putStrLn $ (pure "A Line!" `mappend` (evnt >>= return))

and the same with the penultimate line commented instead of the last, appear
to have different behaviours: in the version shown, "A Line!" is printed
when the program starts; and in the other, this is delayed until after the
first line is read (but before it is printed).

Should this happen?

Freddie Manners

2009/3/29 Mads Lindstrøm 
...
Hi
As part of studying the Reactive library, I have created a simple game.
The object of the game is to guess a number.
As I am a newbie with respect to FRP, I assume that my game could have
been implemented more elegantly. Comments are most welcome.
The game can be found here
http://hpaste.org/fastcgi/hpaste.fcgi/view?id=3037#a3037 and it is
attached.
Greetings,
Mads Lindstrøm
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Re: [reactive] Feedback on my first Reactive program: Monad Laws

Freddie Manners

Freddie Manners

Jake McArthur

Conal Elliott

Freddie Manners

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