--
-- Maintainer : libraries@haskell.org
-- Stability : experimental
--- Portability : non-portable
+-- Portability : non-portable (MPTCs, uses Control.Monad.ST)
--
-- Basis for IArray and MArray. Not intended for external consumption;
-- use IArray or MArray instead.
import Prelude
+import Control.Monad.ST.Lazy ( strictToLazyST )
+import qualified Control.Monad.ST.Lazy as Lazy (ST)
import Data.Ix ( Ix, range, index, rangeSize )
import Data.Int
import Data.Word
-- the type looks like constrained over 's', which runST doesn't
-- like. In fact all MArray (STUArray s) instances are polymorphic
-- wrt. 's', but runST can't know that.
-
--- I would like to write a rule for listUArrayST (or listArray or
+--
+-- More precisely, we'd like to write this:
+-- listUArray :: (forall s. MArray (STUArray s) e (ST s), Ix i)
+-- => (i,i) -> [e] -> UArray i e
+-- listUArray lu = runST (listUArrayST lu es >>= unsafeFreezeSTUArray)
+-- {-# RULES listArray = listUArray
+-- Then we could call listUArray at any type 'e' that had a suitable
+-- MArray instance. But sadly we can't, because we don't have quantified
+-- constraints. Hence the mass of rules below.
+
+-- I would like also to write a rule for listUArrayST (or listArray or
-- whatever) applied to unpackCString#. Unfortunately unpackCString#
-- calls seem to be floated out, then floated back into the middle
-- of listUArrayST, so I was not able to do this.
+#ifdef __GLASGOW_HASKELL__
+type ListUArray e = forall i . Ix i => (i,i) -> [e] -> UArray i e
+
{-# RULES
-"listArray/UArray/Bool" listArray = \lu (es :: [Bool]) ->
- runST (listUArrayST lu es >>= unsafeFreezeSTUArray)
-"listArray/UArray/Char" listArray = \lu (es :: [Char]) ->
- runST (listUArrayST lu es >>= unsafeFreezeSTUArray)
-"listArray/UArray/Int" listArray = \lu (es :: [Int]) ->
- runST (listUArrayST lu es >>= unsafeFreezeSTUArray)
-"listArray/UArray/Word" listArray = \lu (es :: [Word]) ->
- runST (listUArrayST lu es >>= unsafeFreezeSTUArray)
-"listArray/UArray/Ptr" listArray = \lu (es :: [Ptr a]) ->
- runST (listUArrayST lu es >>= unsafeFreezeSTUArray)
-"listArray/UArray/FunPtr" listArray = \lu (es :: [FunPtr a]) ->
- runST (listUArrayST lu es >>= unsafeFreezeSTUArray)
-"listArray/UArray/Float" listArray = \lu (es :: [Float]) ->
- runST (listUArrayST lu es >>= unsafeFreezeSTUArray)
-"listArray/UArray/Double" listArray = \lu (es :: [Double]) ->
- runST (listUArrayST lu es >>= unsafeFreezeSTUArray)
-"listArray/UArray/StablePtr" listArray = \lu (es :: [StablePtr a]) ->
- runST (listUArrayST lu es >>= unsafeFreezeSTUArray)
-"listArray/UArray/Int8" listArray = \lu (es :: [Int8]) ->
- runST (listUArrayST lu es >>= unsafeFreezeSTUArray)
-"listArray/UArray/Int16" listArray = \lu (es :: [Int16]) ->
- runST (listUArrayST lu es >>= unsafeFreezeSTUArray)
-"listArray/UArray/Int32" listArray = \lu (es :: [Int32]) ->
- runST (listUArrayST lu es >>= unsafeFreezeSTUArray)
-"listArray/UArray/Int64" listArray = \lu (es :: [Int64]) ->
- runST (listUArrayST lu es >>= unsafeFreezeSTUArray)
-"listArray/UArray/Word8" listArray = \lu (es :: [Word8]) ->
- runST (listUArrayST lu es >>= unsafeFreezeSTUArray)
-"listArray/UArray/Word16" listArray = \lu (es :: [Word16]) ->
- runST (listUArrayST lu es >>= unsafeFreezeSTUArray)
-"listArray/UArray/Word32" listArray = \lu (es :: [Word32]) ->
- runST (listUArrayST lu es >>= unsafeFreezeSTUArray)
-"listArray/UArray/Word64" listArray = \lu (es :: [Word64]) ->
- runST (listUArrayST lu es >>= unsafeFreezeSTUArray)
+"listArray/UArray/Bool" listArray
+ = (\lu es -> runST (listUArrayST lu es >>= unsafeFreezeSTUArray)) :: ListUArray Bool
+"listArray/UArray/Char" listArray
+ = (\lu es -> runST (listUArrayST lu es >>= unsafeFreezeSTUArray)) :: ListUArray Char
+"listArray/UArray/Int" listArray
+ = (\lu es -> runST (listUArrayST lu es >>= unsafeFreezeSTUArray)) :: ListUArray Int
+"listArray/UArray/Word" listArray
+ = (\lu es -> runST (listUArrayST lu es >>= unsafeFreezeSTUArray)) :: ListUArray Word
+"listArray/UArray/Ptr" listArray
+ = (\lu es -> runST (listUArrayST lu es >>= unsafeFreezeSTUArray)) :: ListUArray (Ptr a)
+"listArray/UArray/FunPtr" listArray
+ = (\lu es -> runST (listUArrayST lu es >>= unsafeFreezeSTUArray)) :: ListUArray (FunPtr a)
+"listArray/UArray/Float" listArray
+ = (\lu es -> runST (listUArrayST lu es >>= unsafeFreezeSTUArray)) :: ListUArray Float
+"listArray/UArray/Double" listArray
+ = (\lu es -> runST (listUArrayST lu es >>= unsafeFreezeSTUArray)) :: ListUArray Double
+"listArray/UArray/StablePtr" listArray
+ = (\lu es -> runST (listUArrayST lu es >>= unsafeFreezeSTUArray)) :: ListUArray (StablePtr a)
+"listArray/UArray/Int8" listArray
+ = (\lu es -> runST (listUArrayST lu es >>= unsafeFreezeSTUArray)) :: ListUArray Int8
+"listArray/UArray/Int16" listArray
+ = (\lu es -> runST (listUArrayST lu es >>= unsafeFreezeSTUArray)) :: ListUArray Int16
+"listArray/UArray/Int32" listArray
+ = (\lu es -> runST (listUArrayST lu es >>= unsafeFreezeSTUArray)) :: ListUArray Int32
+"listArray/UArray/Int64" listArray
+ = (\lu es -> runST (listUArrayST lu es >>= unsafeFreezeSTUArray)) :: ListUArray Int64
+"listArray/UArray/Word8" listArray
+ = (\lu es -> runST (listUArrayST lu es >>= unsafeFreezeSTUArray)) :: ListUArray Word8
+"listArray/UArray/Word16" listArray
+ = (\lu es -> runST (listUArrayST lu es >>= unsafeFreezeSTUArray)) :: ListUArray Word16
+"listArray/UArray/Word32" listArray
+ = (\lu es -> runST (listUArrayST lu es >>= unsafeFreezeSTUArray)) :: ListUArray Word32
+"listArray/UArray/Word64" listArray
+ = (\lu es -> runST (listUArrayST lu es >>= unsafeFreezeSTUArray)) :: ListUArray Word64
#-}
+#endif
{-# INLINE (!) #-}
-- | Returns the element of an immutable array at the specified index.
{-# INLINE unsafeWrite #-}
unsafeWrite = ArrST.unsafeWriteSTArray
+instance MArray (STArray s) e (Lazy.ST s) where
+ {-# INLINE newArray #-}
+ newArray (l,u) e = strictToLazyST (ArrST.newSTArray (l,u) e)
+ {-# INLINE unsafeRead #-}
+ unsafeRead arr i = strictToLazyST (ArrST.unsafeReadSTArray arr i)
+ {-# INLINE unsafeWrite #-}
+ unsafeWrite arr i e = strictToLazyST (ArrST.unsafeWriteSTArray arr i e)
+
#ifdef __HUGS__
INSTANCE_TYPEABLE3(STArray,sTArrayTc,"STArray")
#endif
Note that because the array is possibly not copied, any subsequent
modifications made to the mutable version of the array may be
- shared with the immutable version. It is safe to use, therefore, if
- the immutable version is never referenced again.
+ shared with the immutable version. It is only safe to use,
+ therefore, if the immutable array is never referenced again in this
+ thread, and there is no possibility that it can be also referenced
+ in another thread. If you use an unsafeThaw/write/unsafeFreeze
+ sequence in a multi-threaded setting, then you must ensure that
+ this sequence is atomic with respect to other threads, or a garbage
+ collector crash may result (because the write may be writing to a
+ frozen array).
The non-copying implementation is supported between certain pairs
of array types only; one constraint is that the array types must
have identical representations. In GHC, The following pairs of
array types have a non-copying O(1) implementation of
- 'unsafeFreeze'. Because the optimised versions are enabled by
+ 'unsafeThaw'. Because the optimised versions are enabled by
specialisations, you will need to compile with optimisation (-O) to
get them.
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