Actually this is something that is not in any way specific to MASON. The 

ABM Frameworks I know usually assume you are working on mutable data in 

sequence.



I like the problem because it relates to the question of mutable vs. 

immutable data.



It is easily thinkable to e.g. have an agent that produces a new agent 

as a result, thus making the agent immutable. Or to have an environment 

that is immutable and some process produces a new environment for the 

next round. This is actually kind of what Sean's double buffer approach 

would do.



What would be an advantage is that this would allow for parallel 

processing, besides meeting the religious beliefs of the functional crowd.*



At least as long as there is no interdependencies between agents and the 

changed state of other agents e.g. their new positions.



This where it gets kind of funny:

On 2014-02-27 02:36, Sean Luke wrote:

>   they'll need to make sure that they don't overwrite each other in field B.



How could one ensure that movement works if agents only know a picture 

of where the other agents have been and then call them to move blindly? 

They will inevitably run into each other. How would you try to avoid 

that? You could check in the new field that then would have to be 

mutable reflecting the current agent positions. This would have to be 

changed in sequence. Thus there is a dependence on mutable data, calling 

for synchronization.



Possible solutions would maybe either be actually span a copy of the 

field just for the neighbourhood calculations, use Sean's double buffer 

approach or to use Chris' "two rounds" approach, where first all agents 

get called for some calculations and then they get called for a second 

time to move.



The "two-rounds" approach would allow for putting the first round in a 

ParallelSequence, if you mind the other synchronization issues e.g. with 

the Random Number Generator.





cheers

roman



* Does anybody know if somebody ever tried to produce a functional ABM 

framework? I wouldn't want to use it but I would like to see it. As a 

tourist.