63 lines
1.6 KiB
Haskell
63 lines
1.6 KiB
Haskell
{--
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HSFM, a filemanager written in Haskell.
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Copyright (C) 2016 Julian Ospald
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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version 2 as published by the Free Software Foundation.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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--}
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{-# OPTIONS_HADDOCK ignore-exports #-}
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-- |Random and general IO utilities.
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module HSFM.Utils.IO where
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import Control.Concurrent.STM
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(
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atomically
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)
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import Control.Concurrent.STM.TVar
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(
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writeTVar
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, modifyTVar
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, TVar
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)
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import Control.Monad
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(
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when
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, unless
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)
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-- |Atomically write a TVar.
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writeTVarIO :: TVar a -> a -> IO ()
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writeTVarIO tvar val = atomically $ writeTVar tvar val
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-- |Atomically modify a TVar.
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modifyTVarIO :: TVar a -> (a -> a) -> IO ()
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modifyTVarIO tvar f = atomically $ modifyTVar tvar f
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-- |If the value of the first argument is True, then execute the action
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-- provided in the second argument, otherwise do nothing.
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whenM :: Monad m => m Bool -> m () -> m ()
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whenM mb a = mb >>= (`when` a)
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-- |If the value of the first argument is False, then execute the action
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-- provided in the second argument, otherwise do nothing.
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unlessM :: Monad m => m Bool -> m () -> m ()
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unlessM mb a = mb >>= (`unless` a)
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