Safe Haskell | None |
---|---|
Language | Haskell2010 |
RIO.Vector.Unboxed.Unsafe
Description
Unoxed Vector
unsafe functions. These perform no bounds
checking, and may cause segmentation faults etc.! Import as:
import qualified RIO.Vector.Unoxed.Unsafe as VU'
Synopsis
- unsafeIndex :: Unbox a => Vector a -> Int -> a
- unsafeHead :: Unbox a => Vector a -> a
- unsafeLast :: Unbox a => Vector a -> a
- unsafeIndexM :: (Unbox a, Monad m) => Vector a -> Int -> m a
- unsafeHeadM :: (Unbox a, Monad m) => Vector a -> m a
- unsafeLastM :: (Unbox a, Monad m) => Vector a -> m a
- unsafeSlice :: Unbox a => Int -> Int -> Vector a -> Vector a
- unsafeInit :: Unbox a => Vector a -> Vector a
- unsafeTail :: Unbox a => Vector a -> Vector a
- unsafeTake :: Unbox a => Int -> Vector a -> Vector a
- unsafeDrop :: Unbox a => Int -> Vector a -> Vector a
- unsafeUpd :: Unbox a => Vector a -> [(Int, a)] -> Vector a
- unsafeUpdate :: Unbox a => Vector a -> Vector (Int, a) -> Vector a
- unsafeUpdate_ :: Unbox a => Vector a -> Vector Int -> Vector a -> Vector a
- unsafeAccum :: Unbox a => (a -> b -> a) -> Vector a -> [(Int, b)] -> Vector a
- unsafeAccumulate :: (Unbox a, Unbox b) => (a -> b -> a) -> Vector a -> Vector (Int, b) -> Vector a
- unsafeAccumulate_ :: (Unbox a, Unbox b) => (a -> b -> a) -> Vector a -> Vector Int -> Vector b -> Vector a
- unsafeBackpermute :: Unbox a => Vector a -> Vector Int -> Vector a
- unsafeFreeze :: (Unbox a, PrimMonad m) => MVector (PrimState m) a -> m (Vector a)
- unsafeThaw :: (Unbox a, PrimMonad m) => Vector a -> m (MVector (PrimState m) a)
- unsafeCopy :: (Unbox a, PrimMonad m) => MVector (PrimState m) a -> Vector a -> m ()
Accessors
Indexing
unsafeIndex :: Unbox a => Vector a -> Int -> a #
O(1) Unsafe indexing without bounds checking.
unsafeHead :: Unbox a => Vector a -> a #
O(1) First element, without checking if the vector is empty.
unsafeLast :: Unbox a => Vector a -> a #
O(1) Last element, without checking if the vector is empty.
Monadic indexing
unsafeIndexM :: (Unbox a, Monad m) => Vector a -> Int -> m a #
O(1) Indexing in a monad, without bounds checks. See indexM
for an
explanation of why this is useful.
unsafeHeadM :: (Unbox a, Monad m) => Vector a -> m a #
O(1) First element in a monad, without checking for empty vectors.
See indexM
for an explanation of why this is useful.
unsafeLastM :: (Unbox a, Monad m) => Vector a -> m a #
O(1) Last element in a monad, without checking for empty vectors.
See indexM
for an explanation of why this is useful.
Extracting subvectors
O(1) Yield a slice of the vector without copying. The vector must
contain at least i+n
elements, but this is not checked.
unsafeInit :: Unbox a => Vector a -> Vector a #
O(1) Yield all but the last element without copying. The vector may not be empty, but this is not checked.
unsafeTail :: Unbox a => Vector a -> Vector a #
O(1) Yield all but the first element without copying. The vector may not be empty, but this is not checked.
unsafeTake :: Unbox a => Int -> Vector a -> Vector a #
O(1) Yield the first n
elements without copying. The vector must
contain at least n
elements, but this is not checked.
unsafeDrop :: Unbox a => Int -> Vector a -> Vector a #
O(1) Yield all but the first n
elements without copying. The vector
must contain at least n
elements, but this is not checked.
Modifying vectors
Bulk updates
unsafeUpd :: Unbox a => Vector a -> [(Int, a)] -> Vector a #
Same as (//
), but without bounds checking.
unsafeUpdate :: Unbox a => Vector a -> Vector (Int, a) -> Vector a #
Same as update
, but without bounds checking.
unsafeUpdate_ :: Unbox a => Vector a -> Vector Int -> Vector a -> Vector a #
Same as update_
, but without bounds checking.
Accumulations
unsafeAccum :: Unbox a => (a -> b -> a) -> Vector a -> [(Int, b)] -> Vector a #
Same as accum
, but without bounds checking.
unsafeAccumulate :: (Unbox a, Unbox b) => (a -> b -> a) -> Vector a -> Vector (Int, b) -> Vector a #
Same as accumulate
, but without bounds checking.
unsafeAccumulate_ :: (Unbox a, Unbox b) => (a -> b -> a) -> Vector a -> Vector Int -> Vector b -> Vector a #
Same as accumulate_
, but without bounds checking.
Permutations
unsafeBackpermute :: Unbox a => Vector a -> Vector Int -> Vector a #
Same as backpermute
, but without bounds checking.
Conversions
Mutable vectors
unsafeFreeze :: (Unbox a, PrimMonad m) => MVector (PrimState m) a -> m (Vector a) #
O(1) Unsafely convert a mutable vector to an immutable one without copying. The mutable vector may not be used after this operation.
unsafeThaw :: (Unbox a, PrimMonad m) => Vector a -> m (MVector (PrimState m) a) #
O(1) Unsafely convert an immutable vector to a mutable one without copying. Note that this is a very dangerous function and generally it's only safe to read from the resulting vector. In this case, the immutable vector could be used safely as well.
Problems with mutation happen because GHC has a lot of freedom to
introduce sharing. As a result mutable vectors produced by
unsafeThaw
may or may not share the same underlying buffer. For
example:
foo = do let vec = V.generate 10 id mvec <- V.unsafeThaw vec do_something mvec
Here GHC could lift vec
outside of foo which means that all calls to
do_something
will use same buffer with possibly disastrous
results. Whether such aliasing happens or not depends on the program in
question, optimization levels, and GHC flags.
All in all, attempts to modify a vector produced by unsafeThaw
fall out of
domain of software engineering and into realm of black magic, dark
rituals, and unspeakable horrors. The only advice that could be given
is: "Don't attempt to mutate a vector produced by unsafeThaw
unless you
know how to prevent GHC from aliasing buffers accidentally. We don't."