/usr/lib/hugs/packages/base/Data/STRef.hs is in libhugs-base-bundled 98.200609.21-5.3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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-- |
-- Module : Data.STRef
-- Copyright : (c) The University of Glasgow 2001
-- License : BSD-style (see the file libraries/base/LICENSE)
--
-- Maintainer : libraries@haskell.org
-- Stability : experimental
-- Portability : non-portable (uses Control.Monad.ST)
--
-- Mutable references in the (strict) ST monad.
--
-----------------------------------------------------------------------------
module Data.STRef (
-- * STRefs
STRef, -- abstract, instance Eq
newSTRef, -- :: a -> ST s (STRef s a)
readSTRef, -- :: STRef s a -> ST s a
writeSTRef, -- :: STRef s a -> a -> ST s ()
modifySTRef -- :: STRef s a -> (a -> a) -> ST s ()
) where
import Prelude
import Hugs.ST
import Data.Typeable
stRefTc = mkTyCon "STRef"; instance Typeable2 STRef where { typeOf2 _ = mkTyConApp stRefTc [] }; instance Typeable a => Typeable1 (STRef a) where { typeOf1 = typeOf1Default }; instance (Typeable a, Typeable b) => Typeable (STRef a b) where { typeOf = typeOfDefault }
-- |Mutate the contents of an 'STRef'
modifySTRef :: STRef s a -> (a -> a) -> ST s ()
modifySTRef ref f = writeSTRef ref . f =<< readSTRef ref
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