[Martin Meyer]

Hello Thomas,

in a new GUI project, I insert the following for onFileNew:

Code: Select all

predicates
    onFileNew : window::menuItemListener.
clauses
    onFileNew(_Source, _MenuTag) :-
        _Future = pfc\asynchronous\future::submit_unit(workLots),
        stdIO::write("submitted").
 
class predicates
    workLots : () suspending.
clauses
    workLots() :-
        std::repeat(),
        fail.
 
    workLots().

When I execute the project and click on the "New" icon, the text "submitted" is not displayed, and the task window becomes unresponsive.

However, my intention is to allow the user to continue working with the GUI while workLots runs in the background.

I suspect I need to use a different execution context to achieve the desired behavior, but I cannot figure out how to do it. Please help.

[Martin Meyer]

That way it works better in my tests:

Code: Select all

predicates
    onFileNew : window::menuItemListener.
clauses
    onFileNew(_Source, _MenuTag) :-
        _Future = pfc\asynchronous\future::submit_unit({  :- workLots_susp(0) }),
        stdIO::write("submitted\n").
 
class predicates
    workLots_susp : (integer Cnt) suspending.
clauses
    workLots_susp(Cnt) :-
        stdIO::write(Cnt, "\n"),
        pfc\asynchronous\executionContext::yield(), 
        Cnt1 = if Cnt = upperBound(integer) then 0 else Cnt + 1 end if,
        workLots_susp(Cnt1).

So, does workLots_susp actually need to be repeatedly suspended to keep the task window responsive? Is the above pattern (i.e., inserting calls to yield) suitable for use in my "real" applications, or are there other aspects to consider? Do I need to worry about execution contexts, or is that usually unnecessary?

[Martin Meyer]

In my real application, the long-running process that I want to run in the background is a call to an Earley parser.

If I would insert calls to yield into the parser's routines, I needed to turn at least the parser's top-level routines into suspending predicates. However, that does not seem elegant to me. Is there a way to keep suspension issues outside of the parser's code while still ensuring the responsiveness of the task window?