49 lines
1.3 KiB
Haskell
49 lines
1.3 KiB
Haskell
{- | Module : API
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Maintainer : emi@haskell.fyi
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Description: API for script exporter.
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API for script exporter.
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-}
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module Data.Cache.Cached (
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cached,
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cachedM,
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cachedForM,
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) where
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import Control.Monad.IO.Class (MonadIO (liftIO))
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import Data.Cache qualified as Cache
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import Data.Functor ((<&>))
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import Data.Hashable (Hashable)
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import System.Clock (TimeSpec)
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{- | 'cachedFor' but items last forever.
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Uses a HashMap under the hood.
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-}
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cached :: (Monad m, MonadIO m, Hashable k, Ord k) => (k -> v) -> IO (k -> m v)
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cached f = cachedForM Nothing (pure . f)
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{- | 'cachedFor' but items last forever.
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Uses a HashMap under the hood.
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-}
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cachedM :: (Monad m, MonadIO m, Hashable k, Ord k) => (k -> m v) -> IO (k -> m v)
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cachedM = cachedForM Nothing
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{- | Create a cached version of a function tainting result with MonadIO context.
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Results are cached dependent on the first argument, @'Maybe' 'TimeSpec'@.
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Uses a HashMap under the hood.
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-}
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cachedForM :: (Monad m, MonadIO m, Hashable k, Ord k) => Maybe TimeSpec -> (k -> m v) -> IO (k -> m v)
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cachedForM t f =
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Cache.newCache t <&> \cache k -> do
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res <- liftIO $ Cache.lookup cache k
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case res of
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Nothing -> do
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v <- f k
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liftIO $ Cache.insert cache k v
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pure v
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Just v -> do
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pure v
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