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{-# LANGUAGE Trustworthy #-}
{-# LANGUAGE BangPatterns, CPP, GeneralizedNewtypeDeriving, MagicHash,
NoImplicitPrelude, UnboxedTuples #-}
module GHC.Event.Unique
(
UniqueSource
, Unique(..)
, newSource
, newUnique
) where
import GHC.Base
import GHC.Num(Num)
import GHC.Show(Show(..))
#include "MachDeps.h"
data UniqueSource = US (MutableByteArray# RealWorld)
newtype Unique = Unique { asInt :: Int }
deriving ( Eq -- ^ @since 4.4.0.0
, Ord -- ^ @since 4.4.0.0
, Num -- ^ @since 4.4.0.0
)
-- | @since 4.3.1.0
instance Show Unique where
show = show . asInt
newSource :: IO UniqueSource
newSource = IO $ \s ->
case newByteArray# size s of
(# s', mba #) -> (# s', US mba #)
where
!(I# size) = SIZEOF_HSINT
newUnique :: UniqueSource -> IO Unique
newUnique (US mba) = IO $ \s ->
case fetchAddIntArray# mba 0# 1# s of
(# s', a #) -> (# s', Unique (I# a) #)
{-# INLINE newUnique #-}
|
