[Haskell-beginners] Trying to write netwire combiner similar to multicast

[Nathan Hüsken]

On 11/05/2012 05:29 PM, Ertugrul Söylemez wrote:
> Nathan Hüsken <nathan.huesken at posteo.de> wrote:
> 
>> I am trying to write a netwire combiner similar to multicast. The only
>> difference is that when one of the wires inihibts, I want to remove it
>> from the list.
>>
>> So this is my attempt:
>>
>> manager :: (Monad m) => [Wire e m a b] -> Wire e m [a] [b]
>> manager ws' = mkGen $ \dt xs' -> do
>>             res <- mapM (\(w,x) -> stepWire w dt x) $ zip ws' xs'
>>             let filt (Left a, b) = Just (a, b)
>>                 filt _           = Nothing
>>                 resx = mapMaybe filt res
>>             return (Left $ (fmap fst) resx,manager (fmap snd resx))
> 
> Notice that Left means inhibition (...).

I was sure right meant inhibition ... thanks!

> Also your interface seems very unsafe to me.  I suggest the following
> interface instead:
> 
>     shrinking :: (Monad m) => [Wire e m a b] -> Wire e m a [b]
> 
> Then normally 'a' could be something like Map K A.

That would mean, the individual wires have to know there own id?!?
Mmmh, I will try to keep this bookkeeping out of the wires with this
interface:

shrinking :: (Monad m) => [Wire e m a b] -> Wire e m (Map Int a) (Int,b)

shrinking will assign the ids to the wires and returns them with the
result. I will see where this gets me ... :).

Regards,
Nathan