A minimal actors implementation that makes use of Raku's meta-programming support to abstract away the ordered asynchronous dispatch.

The OO::Actors module provides an actor declarator. Beyond that, it's very much like writing a normal class.

use OO::Actors;

enum Severity <Fatal Error Warning Notice>;

actor EventLog {
    has %!events-by-level{Severity};
    
    method log(Severity $level, Str $message) {
        push %!events-by-level{$level}, $message;
    }

    method latest-entries(Severity $level-limit) {
        my @found;
        for %!events-by-level.kv -> $level, @messages {
            next if $level > $level-limit;
            push @found, @messages;
        }
        return @found;
    }
}

Method calls to an actor are asynchronous. That is, making a method call puts the method name and arguments into a queue. Note that this means you'd better not pass things and then mutate them! Methods are run in the thread pool, one call at a time.

Since method calls on an actor are asynchronous, how do you cope with query methods? Each method call on an actor returns a Promise. This can be used to get the result;

say await $log.latest-entries(Error);