Set options temporarily - useful with Network.HTTP.Conduit.Browser

SaveRestore.hs

import qualified Control.Exception.Lifted as Lifted
import Control.Monad.Trans.Control

-- | Set an option, run an action, then restore the option to its
-- previous value.
--
-- @saveRestore get set value action@ is roughly equivalent to:
--
-- > do orig <- get
-- >    set value
-- >    action
-- >    set orig
--
-- except with proper exception handling.
saveRestore
    :: MonadBaseControl IO m
    => m a         -- ^ get value
    -> (a -> m ()) -- ^ set value
    -> a           -- ^ value to set
    -> m r         -- ^ action to run in between
    -> m r
saveRestore get set value action = Lifted.bracket open close between
  where
    open = do
        orig <- get
        set value
        return orig
    close = set
    between _ = action