waitAll

Constructs a new task that waits all given tasks resolve. The result of the new task is an array with the results of the input tasks, if they all succeed, or the first failure if they fail.

This feature is experimental!

This API is still experimental, so it may change or be removed in future versions. You should not rely on it for production applications.

Signature

waitAll(tasks)

Type(what is this?)

forall v, e: ([Task e v Any]) => Task e [v] Any

Documentation

Constructs a new task that waits all given tasks resolve. The result of the new task is an array with the results of the input tasks, if they all succeed, or the first failure if they fail.

While the tasks are started in the order they appear in the array, the function will not wait one task to finish before starting another. For asynchronous tasks this effectively gives you concurrent execution.

Note that cancelling one of the input tasks will cancel the combined task as well. Cancelling the combined task will cancel all of the input tasks. If any of the input tasks fails, all of the other input tasks will be cancelled as well.

Example:

const { of, waitAll } = require('folktale/concurrency/task');

const result = await waitAll([
  of(1),
  of(2),
  of(3)
]).run().promise();

$ASSERT(result == [1, 2, 3]);

Properties

Source Code

Defined in source/concurrency/task/wait-all.js at line 17, column 0

(tasks) => {
  return tasks.reduce(
    (a, b) => a.and(b).map(([xs, x]) => [...xs, x]),
    of([])
  );
}