Re: Multiple environments

Hi Felix,

Thanks for the reply.

> On 16. Jun 2024, at 11:27, [email protected] wrote:
> 
> You can use modules in combination with "eval" to isolate global environments.
> First you create a module at runtime using via "(eval '(module ...))" and then
> evaluate an expression in the context of the module by using "module-environment",
> passing this env as a second argument to eval. This has several restrictions,
> though, so it is not equivalent to the way your Racket implementation works.

Indeed, this has the issue that the module passed as second argument is not mutable.

> Also you probably want to compile your code instead of evaluation code at
> runtime. Would it be possible to use a different syntax for global variable
> accesses (both read and write, so something like "get" and "put" operations)?
> That would make the implementation much easier and also has the benefit of
> making global accesses more obvious to the one reading the code and it also
> helps to make the code more portable to other Scheme implementations.

Actually, no. I was planning not to compile the actors code. The idea is that the simulator takes the a “model” as input besides the number of actors. The model is the code executed by the actors. I guess that this boils down to using eval, right?

> Is the set of globals fixed or can an actor extend this set? Do you want to
> compile your code (I assume you do)? Do you want these globals to be fully
> equivalent to normal global bindings?

For the globals that are *shared* among actors, I’m already using an interface. That makes the accesses to shared data fully explicit (it’s just a hash-table in the background). But I wanted to allow the user to write the actors’ “models“ as plain scheme. At the end of the day, however, this is not a tremendous problem. I was just curious to see if it would be possible to implement.

For now,  I will follow your suggestion and move the accesses to global state (whether shared or not) behind a get-put interface. I think that later, using macros, I can hide/simplify the input of the user.

Thanks for the suggestions.

Best,
-Diogo