Use promise_all to wait for multiple promise objects to all be successfully fulfilled. Use promise_race to wait for the first of multiple promise objects to be either fulfilled or rejected.

promise_all(..., .list = NULL)

promise_race(..., .list = NULL)



Promise objects. Either all arguments must be named, or all arguments must be unnamed. If .list is provided, then these arguments are ignored.


A list of promise objects--an alternative to ....


A promise.

For promise_all, if all of the promises were successful, the returned promise will resolve to a list of the promises' values; if any promise fails, the first error to be encountered will be used to reject the returned promise.

For promise_race, the first of the promises to either fulfill or reject will be passed through to the returned promise.


p1 <- promise(~later::later(~resolve(1), delay = 1)) p2 <- promise(~later::later(~resolve(2), delay = 2)) # Resolves after 1 second, to the value: 1 promise_race(p1, p2) %...>% { cat("promise_race:\n") str(.) } # Resolves after 2 seconds, to the value: list(1, 2) promise_all(p1, p2) %...>% { cat("promise_all:\n") str(.) }