Re: [Haskell-cafe] How to implement a digital filter, using Arrows?

On 21/10/2011 3:00 AM, David Barbour wrote: the f in (Automaton f) is a pure funtion runAuto is deconstructing the arrow by pattern matching then applying the function to the input to obtain the result and the continuation. i.e. runAuto takes an arrow and applies it to a value.

On Thu, Oct 20, 2011 at 5:19 AM, Captain Freakowrote:

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Hi David,

I was referring to the `f' in the `runAuto' function, not the `liftAu' function.

-db

Ah, I see. You quoted one thing and spoke of another, and I got all confused. Keep in mind that functions are arrows (instance Arrow (->)).

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type FilterAu b c = Automaton (->) b c runAuto :: FilterAu b c -> [b] -> [c] runAuto a [] = [] runAuto (Automaton f) (x:xs) = let (y,a) = f x in y:runAuto a xs