Course of Raku / Functional, concurrent, reactive, and web programming / Reactive programming / react and whenever / Exercises / Upper-case with react

Solution: Upper-case with react

Here is a possible solution to the task.

Code

my @collected;

react {
    whenever Supply.from-list('a', 'b', 'c') {
        @collected.push($_.uc);
    }
}

say @collected;

🦋 You can find the source code in the file react-upcase.raku.

Output

[A B C]

Comments

1. The whenever body runs once per value, upper-casing it and pushing it onto @collected.

2. react waits for the single supply to finish, so by the time say runs the array holds all three values in order: [A B C].

3. A supply has list-like methods of its own, so you could upper-case in the stream instead of in the body — whenever Supply.from-list('a', 'b', 'c').map(*.uc) { @collected.push($_) } — and the effect is the same. .map on a supply transforms each value as it flows past; the choice is simply whether the transformation belongs to the stream or to the reaction.

Course navigation

← Upper-case with react   |   Sort into two arrays →