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Functional design for a basic simulation pipe.
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Date: -- (:)
From: Hugo Ferreira <hmf@i...>
Subject: Re: [Caml-list] Functional design for a basic simulation pipe.
Hello,

Vincent Aravantinos wrote:
> 
> Le 10 oct. 07 à 12:08, Hugo Ferreira a écrit :
> 
>> Apologies for being so obtuse but I cannot to see how this solves my
>> problem. Please note that I am not well versed in functional programming
>> so that what I am asking may not be possible. Lets say I have a small
>> pipe of 3 actions:
>>
>> let exp = a |> b |> c
>>
>> a: requires the input of a state and outputs an event
>> b: requires input of a state and the event generated at that state and
>> outputs processed data
>> c: consumes n number elements of processed data and stops when it
>> requires no more such data
>>
>> Note that "c" will "pull in" for example 10 states and check for
>> termination, "b" will therefore need "pull in" 10 events. Each time it
>> pulls in an event it generates a state. This last state must be made
>> available to "a" so that it may generate its next event.
>>
>> The issue here is how can I implement this so that I can flexibly
>> configure experiments by "constructing" a chain of actions but still be
>> able to pass back the state to one of those actions. Something like:
>>
>> let exp = a |> b (output 1 back to a) |> c
> 
> Just to be sure I understood well, here is a diagram:
> 
> --> a --> b -+-------------------------------------------------> output1
>              |
>              +--state1-> a --> b -+----------------------------> output2
>                                   |
>                                   +-state2-> a --> b -+--------> output3
>                                                       |
>                                                          ...
>                                                               -> outputn
> 
>                                                                     |
>                                                                     |
>                                                                     |
>                                                                     V
> 
>                                                                     c
> 
> 
> Do you agree with this ? (n beeing a variable of course...)

Not quite. More like:

(_,s0)
-> a-> s0,e1 -> b -+--------------------------------------> s1
                   |
                   +--s1-> a -> s1,e2 -> b-+--------------> s2
                                           |
                                            ...
                                                         -> sn
                                                            |
                                                            |
                                                            |
                                                            V
                                                            c

Note that "a" doesn't generates states "sn" it just passes it on.
It only generates events "en". "b" simple takes a state "sn-1" and the
events "en" and generates a new state "sn".

> Shall c also take the states ?
> 

Yes. But the idea is to add other functions to the "pipe" that will
change states to other data types for further processing.

Note also that only the last function actually knows how much data is
required.

> (I believe in good drawings to help finding an answer...)

Well it certainly easier to express the flow of the data.



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