Is there something that does the same thing as sequenceA
does to [IO a]
, but that runs them concurrently? I don’t need any fancy concurrency stuff like locking since all IO actions are independent.
CodePudding user response:
The async
package works well for this. As mentioned in a comment, mapConcurrently
from that package will run a list of IO actions in parallel. In particular, specialized to a list, the expression mapConcurrently id
has the type you want:
mapConcurrently id :: [IO a] -> IO [a]
so:
import Control.Concurrent.Async
main = mapConcurrently id [putStrLn "foo", putStrLn "bar"]
If you don't care about the return values, use mapConcurrently_ id
instead.
If you don't actually need IO and are really tring to run a bunch of pure computations in parallel, then the parallel
package would be more appropriate.