flatMap

[innermatrix]

Please explain the feature or improvement you would like:

Please add async flatMap

Please describe the use case where you would need that feature (the general situation or type of program where that would be helpful):

Currently the best counterpart to

arr.flatMap((elt) => f(elt))

is

(await asyncMap(arr, async (elt) => await f(elt))).flatMap(elt => elt)

Which is janky. I would prefer

await asyncFlatMap(arr, async (elt) => await f(elt))

Please explain why you think that feature would be helpful to other people:

Because flatMap is in stdlib Array