Data.Primitive.PrimArray

Arrays of unboxed primitive types. The function provided by this module match the behavior of those provided by Data.Primitive.ByteArray, and the underlying types and primops that back them are the same. However, the type constructors PrimArray and MutablePrimArray take one additional argument than their respective counterparts ByteArray and MutableByteArray. This argument is used to designate the type of element in the array. Consequently, all function this modules accepts length and incides in terms of elements, not bytes.

Since: 0.6.4.0

Types

data PrimArray a

Arrays of unboxed elements. This accepts types like Double, Char, Int, and Word, as well as their fixed-length variants (Word8, Word16, etc.). Since the elements are unboxed, a PrimArray is strict in its elements. This differs from the behavior of Array, which is lazy in its elements.

Constructors

PrimArray ByteArray#

Instances

Prim a => IsList (PrimArray a)

Since: 0.6.4.0

Defined in Data.Primitive.PrimArray

Associated Types

type Item (PrimArray a) :: Type

Methods

fromList :: [Item (PrimArray a)] -> PrimArray a

fromListN :: Int -> [Item (PrimArray a)] -> PrimArray a

toList :: PrimArray a -> [Item (PrimArray a)]

(Eq a, Prim a) => Eq (PrimArray a)

Since: 0.6.4.0

Defined in Data.Primitive.PrimArray

Methods

(==) :: PrimArray a -> PrimArray a -> Bool

(/=) :: PrimArray a -> PrimArray a -> Bool

(Ord a, Prim a) => Ord (PrimArray a)

Lexicographic ordering. Subject to change between major versions.

Since: 0.6.4.0

Defined in Data.Primitive.PrimArray

Methods

compare :: PrimArray a -> PrimArray a -> Ordering

(<) :: PrimArray a -> PrimArray a -> Bool

(<=) :: PrimArray a -> PrimArray a -> Bool

(>) :: PrimArray a -> PrimArray a -> Bool

(>=) :: PrimArray a -> PrimArray a -> Bool

max :: PrimArray a -> PrimArray a -> PrimArray a

min :: PrimArray a -> PrimArray a -> PrimArray a

(Show a, Prim a) => Show (PrimArray a)

Since: 0.6.4.0

Defined in Data.Primitive.PrimArray

Methods

showsPrec :: Int -> PrimArray a -> ShowS

show :: PrimArray a -> String

showList :: [PrimArray a] -> ShowS

Semigroup (PrimArray a)

Since: 0.6.4.0

Defined in Data.Primitive.PrimArray

Methods

(<>) :: PrimArray a -> PrimArray a -> PrimArray a

sconcat :: NonEmpty (PrimArray a) -> PrimArray a

stimes :: Integral b => b -> PrimArray a -> PrimArray a

Monoid (PrimArray a)

Since: 0.6.4.0

Defined in Data.Primitive.PrimArray

Methods

mempty :: PrimArray a

mappend :: PrimArray a -> PrimArray a -> PrimArray a

mconcat :: [PrimArray a] -> PrimArray a

type Item (PrimArray a)

Defined in Data.Primitive.PrimArray

type Item (PrimArray a) = a

data MutablePrimArray s a

Mutable primitive arrays associated with a primitive state token. These can be written to and read from in a monadic context that supports sequencing such as IO or ST. Typically, a mutable primitive array will be built and then convert to an immutable primitive array using unsafeFreezePrimArray. However, it is also acceptable to simply discard a mutable primitive array since it lives in managed memory and will be garbage collected when no longer referenced.

Constructors

MutablePrimArray (MutableByteArray# s)

Allocation

newPrimArray :: forall m a. (PrimMonad m, Prim a) => Int -> m (MutablePrimArray (PrimState m) a)

Create a new mutable primitive array of the given length. The underlying memory is left uninitialized.

resizeMutablePrimArray

Arguments

:: (PrimMonad m, Prim a)

=> MutablePrimArray (PrimState m) a

-> Int

new size

-> m (MutablePrimArray (PrimState m) a)

Resize a mutable primitive array. The new size is given in elements.

This will either resize the array in-place or, if not possible, allocate the contents into a new, unpinned array and copy the original array's contents.

To avoid undefined behaviour, the original MutablePrimArray shall not be accessed anymore after a resizeMutablePrimArray has been performed. Moreover, no reference to the old one should be kept in order to allow garbage collection of the original MutablePrimArray in case a new MutablePrimArray had to be allocated.

shrinkMutablePrimArray

Arguments

:: (PrimMonad m, Prim a)

=> MutablePrimArray (PrimState m) a

-> Int

new size

-> m ()

Shrink a mutable primitive array. The new size is given in elements. It must be smaller than the old size. The array will be resized in place. This function is only available when compiling with GHC 7.10 or newer.

Element Access

readPrimArray :: (Prim a, PrimMonad m) => MutablePrimArray (PrimState m) a -> Int -> m a

writePrimArray

Arguments

:: (Prim a, PrimMonad m)

=> MutablePrimArray (PrimState m) a

array

-> Int

index

-> a

element

-> m ()

Write an element to the given index.

indexPrimArray :: forall a. Prim a => PrimArray a -> Int -> a

Read a primitive value from the primitive array.

Freezing and Thawing

unsafeFreezePrimArray :: PrimMonad m => MutablePrimArray (PrimState m) a -> m (PrimArray a)

Convert a mutable byte array to an immutable one without copying. The array should not be modified after the conversion.

unsafeThawPrimArray :: PrimMonad m => PrimArray a -> m (MutablePrimArray (PrimState m) a)

Convert an immutable array to a mutable one without copying. The original array should not be used after the conversion.

Block Operations

copyPrimArray

Arguments

:: (PrimMonad m, Prim a)

=> MutablePrimArray (PrimState m) a

destination array

-> Int

offset into destination array

-> PrimArray a

source array

-> Int

offset into source array

-> Int

number of elements to copy

-> m ()

Copy part of an array into another mutable array.

copyMutablePrimArray

Arguments

:: (PrimMonad m, Prim a)

=> MutablePrimArray (PrimState m) a

destination array

-> Int

offset into destination array

-> MutablePrimArray (PrimState m) a

source array

-> Int

offset into source array

-> Int

number of elements to copy

-> m ()

Copy part of a mutable array into another mutable array. In the case that the destination and source arrays are the same, the regions may overlap.

copyPrimArrayToPtr

Arguments

:: (PrimMonad m, Prim a)

=> Ptr a

destination pointer

-> PrimArray a

source array

-> Int

offset into source array

-> Int

number of prims to copy

-> m ()

Copy a slice of an immutable primitive array to an address. The offset and length are given in elements of type a. This function assumes that the Prim instance of a agrees with the Storable instance. This function is only available when building with GHC 7.8 or newer.

copyMutablePrimArrayToPtr

Arguments

:: (PrimMonad m, Prim a)

=> Ptr a

destination pointer

-> MutablePrimArray (PrimState m) a

source array

-> Int

offset into source array

-> Int

number of prims to copy

-> m ()

Copy a slice of an immutable primitive array to an address. The offset and length are given in elements of type a. This function assumes that the Prim instance of a agrees with the Storable instance. This function is only available when building with GHC 7.8 or newer.

setPrimArray

Arguments

:: (Prim a, PrimMonad m)

=> MutablePrimArray (PrimState m) a

array to fill

-> Int

offset into array

-> Int

number of values to fill

-> a

value to fill with

-> m ()

Fill a slice of a mutable primitive array with a value.

Information

sameMutablePrimArray :: MutablePrimArray s a -> MutablePrimArray s a -> Bool

Check if the two arrays refer to the same memory block.

getSizeofMutablePrimArray

Arguments

:: (PrimMonad m, Prim a)

=> MutablePrimArray (PrimState m) a

array

-> m Int

Get the size of a mutable primitive array in elements. Unlike sizeofMutablePrimArray, this function ensures sequencing in the presence of resizing.

sizeofMutablePrimArray :: forall s a. Prim a => MutablePrimArray s a -> Int

Size of the mutable primitive array in elements. This function shall not be used on primitive arrays that are an argument to or a result of resizeMutablePrimArray or shrinkMutablePrimArray.

sizeofPrimArray :: forall a. Prim a => PrimArray a -> Int

Get the size, in elements, of the primitive array.

List Conversion

primArrayToList :: forall a. Prim a => PrimArray a -> [a]

Convert the primitive array to a list.

primArrayFromList :: Prim a => [a] -> PrimArray a

primArrayFromListN :: forall a. Prim a => Int -> [a] -> PrimArray a

Folding

foldrPrimArray :: forall a b. Prim a => (a -> b -> b) -> b -> PrimArray a -> b

Lazy right-associated fold over the elements of a PrimArray.

foldrPrimArray' :: forall a b. Prim a => (a -> b -> b) -> b -> PrimArray a -> b

Strict right-associated fold over the elements of a PrimArray.

foldlPrimArray :: forall a b. Prim a => (b -> a -> b) -> b -> PrimArray a -> b

Lazy left-associated fold over the elements of a PrimArray.

foldlPrimArray' :: forall a b. Prim a => (b -> a -> b) -> b -> PrimArray a -> b

Strict left-associated fold over the elements of a PrimArray.

foldlPrimArrayM' :: (Prim a, Monad m) => (b -> a -> m b) -> b -> PrimArray a -> m b

Strict left-associated fold over the elements of a PrimArray.

Effectful Folding

traversePrimArray_ :: (Applicative f, Prim a) => (a -> f b) -> PrimArray a -> f ()

Traverse the primitive array, discarding the results. There is no PrimMonad variant of this function since it would not provide any performance benefit.

itraversePrimArray_ :: (Applicative f, Prim a) => (Int -> a -> f b) -> PrimArray a -> f ()

Traverse the primitive array with the indices, discarding the results. There is no PrimMonad variant of this function since it would not provide any performance benefit.

Map/Create

mapPrimArray :: (Prim a, Prim b) => (a -> b) -> PrimArray a -> PrimArray b

Map over the elements of a primitive array.

imapPrimArray :: (Prim a, Prim b) => (Int -> a -> b) -> PrimArray a -> PrimArray b

Indexed map over the elements of a primitive array.

generatePrimArray

Arguments

:: Prim a

=> Int

length

-> (Int -> a)

element from index

-> PrimArray a

Generate a primitive array.

replicatePrimArray

Arguments

:: Prim a

=> Int

length

-> a

element

-> PrimArray a

Create a primitive array by copying the element the given number of times.

filterPrimArray :: Prim a => (a -> Bool) -> PrimArray a -> PrimArray a

Filter elements of a primitive array according to a predicate.

mapMaybePrimArray :: (Prim a, Prim b) => (a -> Maybe b) -> PrimArray a -> PrimArray b

Map over a primitive array, optionally discarding some elements. This has the same behavior as Data.Maybe.mapMaybe.

Effectful Map/Create

The naming conventions adopted in this section are explained in the documentation of the Data.Primitive module.

traversePrimArray

Arguments

:: (Applicative f, Prim a, Prim b)

=> (a -> f b)

mapping function

-> PrimArray a

primitive array

-> f (PrimArray b)

Traverse a primitive array. The traversal performs all of the applicative effects before forcing the resulting values and writing them to the new primitive array. Consequently:

>>> traversePrimArray (\x -> print x $> bool x undefined (x == 2)) (fromList [1, 2, 3 :: Int])
1
2
3
*** Exception: Prelude.undefined

The function traversePrimArrayP always outperforms this function, but it requires a PrimMonad constraint, and it forces the values as it performs the effects.

itraversePrimArray :: (Applicative f, Prim a, Prim b) => (Int -> a -> f b) -> PrimArray a -> f (PrimArray b)

Traverse a primitive array with the index of each element.

generatePrimArrayA

Arguments

:: (Applicative f, Prim a)

=> Int

length

-> (Int -> f a)

element from index

-> f (PrimArray a)

Generate a primitive array by evaluating the applicative generator function at each index.

replicatePrimArrayA

Arguments

:: (Applicative f, Prim a)

=> Int

length

-> f a

applicative element producer

-> f (PrimArray a)

Execute the applicative action the given number of times and store the results in a vector.

filterPrimArrayA

Arguments

:: (Applicative f, Prim a)

=> (a -> f Bool)

mapping function

-> PrimArray a

primitive array

-> f (PrimArray a)

Filter the primitive array, keeping the elements for which the monadic predicate evaluates true.

mapMaybePrimArrayA

Arguments

:: (Applicative f, Prim a, Prim b)

=> (a -> f (Maybe b))

mapping function

-> PrimArray a

primitive array

-> f (PrimArray b)

Map over the primitive array, keeping the elements for which the applicative predicate provides a Just.

Strict Primitive Monadic

traversePrimArrayP :: (PrimMonad m, Prim a, Prim b) => (a -> m b) -> PrimArray a -> m (PrimArray b)

Traverse a primitive array. The traversal forces the resulting values and writes them to the new primitive array as it performs the monadic effects. Consequently:

>>> traversePrimArrayP (\x -> print x $> bool x undefined (x == 2)) (fromList [1, 2, 3 :: Int])
1
2
*** Exception: Prelude.undefined

In many situations, traversePrimArrayP can replace traversePrimArray, changing the strictness characteristics of the traversal but typically improving the performance. Consider the following short-circuiting traversal:

incrPositiveA :: PrimArray Int -> Maybe (PrimArray Int)
incrPositiveA xs = traversePrimArray (\x -> bool Nothing (Just (x + 1)) (x > 0)) xs

This can be rewritten using traversePrimArrayP. To do this, we must change the traversal context to MaybeT (ST s), which has a PrimMonad instance:

incrPositiveB :: PrimArray Int -> Maybe (PrimArray Int)
incrPositiveB xs = runST $ runMaybeT $ traversePrimArrayP
  (\x -> bool (MaybeT (return Nothing)) (MaybeT (return (Just (x + 1)))) (x > 0))
  xs

Benchmarks demonstrate that the second implementation runs 150 times faster than the first. It also results in fewer allocations.

itraversePrimArrayP :: (Prim a, Prim b, PrimMonad m) => (Int -> a -> m b) -> PrimArray a -> m (PrimArray b)

Traverse a primitive array with the indices. The traversal forces the resulting values and writes them to the new primitive array as it performs the monadic effects.

generatePrimArrayP

Arguments

:: (PrimMonad m, Prim a)

=> Int

length

-> (Int -> m a)

generator

-> m (PrimArray a)

Generate a primitive array by evaluating the monadic generator function at each index.

replicatePrimArrayP :: (PrimMonad m, Prim a) => Int -> m a -> m (PrimArray a)

Execute the monadic action the given number of times and store the results in a primitive array.

filterPrimArrayP :: (PrimMonad m, Prim a) => (a -> m Bool) -> PrimArray a -> m (PrimArray a)

Filter the primitive array, keeping the elements for which the monadic predicate evaluates true.

mapMaybePrimArrayP :: (PrimMonad m, Prim a, Prim b) => (a -> m (Maybe b)) -> PrimArray a -> m (PrimArray b)

Map over the primitive array, keeping the elements for which the monadic predicate provides a Just.