Re: [eclipse-users] Suspension lists

On 10/09/2007, at 12:22 PM, Kish Shen wrote:

> Kish Shen wrote:
>>>
>> The global priority system is far from ideal, but we have not been  
>> able to come up with something better, and we have thought about  
>> this for a long time. In the end, it seems to be better than what  
>> other CLP allows -- which I think is just basically a single  
>> priority for suspended goal,
>
> I should have added: we would be very interested in hearing ideas  
> about how to have a better priority system, which
>
> a) can be used across different modules (i.e. libraries), without  
> the user needing to know what priorities are used elsewhere
> b) be implemented efficiently

I can see that it is a non-trivial problem. The beginnings of a  
solution might be:

1) Each module has a local priority-based system, along the lines of  
what already exists, but with an open ended range (no arbitrary cut  
off at 12).
2) Programmers can explicitly create a partial ordering by stating  
how this module related to others, either higher or lower.
3) The command-line is always the bottom. It has no numeric priority.

This would encourage encapsulation, and the priorities of everything  
in a module would not be open to inspection, nor would they need to  
be. I imagine you would typically include ordering statements  
alongside your imports, stating that the imported modules have higher  
precedence. It would also give the programmer a lot more room to move  
within individual modules.

Could this be implemented efficiently? I'm not sure. It depends on  
how efficient you need it to be.

Malcolm

--
      "The act of defending any of the cardinal virtues has today all
       the exhilaration of a vice."
                                     - G.K.Chesterton A Defense of  
Humility