async-refresh: Package implementing core logic for refreshing of expiring data.

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This package can be used for refreshing of expiring data according to a user-provided action. Using callbacks, the user can decide how she or he would like to be informed about data refreshing.

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Versions0.1.7, 0.2.0,,,
Change logNone available
Dependenciesbase (>=4.7 && <5), formatting, lifted-async, microlens, microlens-th, monad-control, monad-logger, safe-exceptions, stm, text [details]
Copyright(c) 2017 Moritz Schulte
AuthorMoritz Schulte
Home page
Source repositoryhead: git clone
UploadedThu Jun 29 17:36:52 UTC 2017 by mtesseract




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Readme for async-refresh-

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async-refresh Hackage version Stackage version Build Status


This is Haskell library implementing the logic for refreshing of expiring data according to user-provided actions.



The following IO action produces a TVar which is updated every ten seconds to contain the current time (wrapped in an Either SomeException, because refreshing may fail).

periodicTimeUpdater :: IO (TVar (Either SomeException UTCTime))
periodicTimeUpdater = runStderrLoggingT $ do
  timeStore <- liftIO $ newTVarIO (Left (toException NotFound))
  let conf = newAsyncRefreshConf (RefreshResult <$> liftIO getCurrentTime <*> pure Nothing)
        & asyncRefreshConfSetLabel "CurrentTime updated every 10 seconds"
        & asyncRefreshConfSetDefaultInterval (10 * 10^3)
        & asyncRefreshConfSetCallback (liftIO . atomically . writeTVar timeStore . fmap refreshResult)
  _ <- newAsyncRefresh conf
  return timeStore