[Haskell-beginners] optimisation of code

[PICCA Frederic-Emmanuel]

Hello,

I would like to have your advice in order to optimize this code.
The purpose is to trigg an action 'a' if a list of files (thousands) exists.
A process copy files from one directory to another.

allFilesThere :: MonadIO m => [Path Abs File] -> m Bool
allFilesThere fs = liftIO $ allM (doesFileExist . fromAbsFile) fs

trigOnAllFiles :: MonadIO m => m r -> [Path Abs File] -> m r
trigOnAllFiles a fs = go
    where
      go = do
        r <- allFilesThere fs
        if r then a else
            ( do liftIO $ threadDelay 1000000
                 go)

It works, but it consums a lot's of resources when all the files does not exists yet.
So I would like your advice in order to optimize it :)

thanks for your help.

Frederic