I'd like to iterate over an associative array and output it's key and value using parallel from std.parallelism.

But I get an error message: ParallelForeach!(int[string]) error instantiating.

My code:

auto example = ["apples": 100, "orange": 250, "banana": 175];
foreach(key, value; parallel(example)) { writeln(key, ": ", value); }

What am I doing wrong?

Thanks in advance.

On Saturday, 17 April 2021 at 01:57:34 UTC, Kirill wrote:

parallel requires a range [1], and an associative array is not a range. To get a range of an AA's keys and values, you can use the method .byKeyValue:

foreach (pair; parallel(example.byKeyValue)) {
    writeln(pair.key, ": ", pair.value);
}

If you're confused about what a "range" is, the short answer is that it's kind of like an iterator. For the long answer, check out Andrei Alexandrescu's article "On Iteration" [2], or the "Ranges" chapter of Ali Çehreli's "Programming in D" [3].

[1] https://phobos.dpldocs.info/std.parallelism.TaskPool.parallel.2.html
[2] https://www.informit.com/articles/printerfriendly/1407357
[3] http://ddili.org/ders/d.en/ranges.html

On Saturday, 17 April 2021 at 02:14:50 UTC, Paul Backus wrote:

foreach (pair; parallel(example.byKeyValue)) {
    writeln(pair.key, ": ", pair.value);
}

That worked! Thanks you!