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{-# LANGUAGE ScopedTypeVariables #-}
-- | Debounce an action, ensuring it doesn't occur more than once for a given
-- period of time.
--
-- This is useful as an optimization, for example to ensure that logs are only
-- flushed to disk at most once per second.
--
-- Example usage:
--
-- @
-- printString <- 'mkDebounce' 'defaultDebounceSettings'
-- { 'debounceAction' = putStrLn "Running action"
-- , 'debounceFreq' = 5000000 -- 5 seconds
-- , 'debounceEdge' = 'DI.trailingEdge' -- Trigger on the trailing edge
-- }
-- @
--
-- >>> printString
-- Running action
-- >>> printString
-- <Wait five seconds>
-- Running action
--
-- See the fast-logger package ("System.Log.FastLogger") for real-world usage.
--
-- @since 0.1.2
module Control.Debounce
( -- * Type
DI.DebounceSettings
, defaultDebounceSettings
-- * Accessors
, DI.debounceFreq
, DI.debounceAction
, DI.debounceEdge
, DI.leadingEdge
, DI.trailingEdge
-- * Creation
, mkDebounce
) where
import Control.Concurrent (newEmptyMVar, threadDelay)
import qualified Control.Debounce.Internal as DI
-- | Default value for creating a 'DebounceSettings'.
--
-- @since 0.1.2
defaultDebounceSettings :: DI.DebounceSettings
defaultDebounceSettings = DI.DebounceSettings
{ DI.debounceFreq = 1000000
, DI.debounceAction = return ()
, DI.debounceEdge = DI.leadingEdge
}
-- | Generate an action which will trigger the debounced action to be performed.
--
-- @since 0.1.2
mkDebounce :: DI.DebounceSettings -> IO (IO ())
mkDebounce settings = do
baton <- newEmptyMVar
DI.mkDebounceInternal baton threadDelay settings
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