Cells, a dataflow extension to CLOS

Dan Lentz | 18 Mar 2012 19:20

functional programming

I'm an extreme newbie to cells and have just begun reviewing the
literature so this may be a FAQ, but in general how does cells relate
to "functional" programming practice?  My first reaction is that is
seems antithetical, as it inherently introduces state and eliminates
referential transparency. However if one looks at it as a declarative
approach in making statements about relations, perhaps not. maybe it
can therefore be used in a functional style along the same lines as
standard clos/mop, which can also be considered stateful if evaluated
at the level of the individual sub protocols etc.

Really my question is "is cells something one should consider if
otherwise one has worked hard to achieve functional style practices?"
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Frank Goenninger | 18 Mar 2012 19:51

Re: functional programming

Hi -

Am 18.03.2012 um 19:20 schrieb Dan Lentz:

> I'm an extreme newbie to cells and have just begun reviewing the
> literature so this may be a FAQ, but in general how does cells relate
> to "functional" programming practice?  My first reaction is that is
> seems antithetical, as it inherently introduces state and eliminates
> referential transparency. However if one looks at it as a declarative
> approach in making statements about relations, perhaps not. maybe it
> can therefore be used in a functional style along the same lines as
> standard clos/mop, which can also be considered stateful if evaluated
> at the level of the individual sub protocols etc.
> 
> Really my question is "is cells something one should consider if
> otherwise one has worked hard to achieve functional style practices?"

I don't know. I am answering questions like this for myself like: If it fits your needs then use it. If it
doesn't, well, then don't use it. I, personally, didn't find anything non-functional in Cells the way I
use it.

Cheers
   Frank

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Kenneth Tilton | 19 Mar 2012 15:24

Re: functional programming

On 3/18/2012 2:20 PM, Dan Lentz wrote:
> I'm an extreme newbie to cells and have just begun reviewing the
> literature so this may be a FAQ, but in general how does cells relate
> to "functional" programming practice?  My first reaction is that is
> seems antithetical, as it inherently introduces state and eliminates
> referential transparency. However if one looks at it as a declarative
> approach in making statements about relations, perhaps not. maybe it
> can therefore be used in a functional style along the same lines as
> standard clos/mop, which can also be considered stateful if evaluated
> at the level of the individual sub protocols etc.
>
> Really my question is "is cells something one should consider if
> otherwise one has worked hard to achieve functional style practices?"

I think you have it about right: Cell rules are nicely declarative and 
generally functional, but in the end Cells is all about managing a 
complex pile of application state representing <whatever real-world 
system we are modelling>. So, for example, the RoboCells implementation 
kept its own internal model of the game, with players and the ball 
modelled as CLOS instances. This model got updated as new sensory inputs 
were received. Sounds like "state" to me. :) That said, I imagine even 
functional programmers have to deal with long-lived models so maybe 
....a monad? Sorry, I wish I knew more about the functional game.

One thought that crosses my mind is Clojure with its functional state 
(if I have that right) and I know some folks over there were playing 
with implementing something Cells-ish in Clojure. Maybe chack in with 
those folks for thoughts from folks more functionally inclined than myself.

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