Create an Array of the given number of elements of type a from a read only pointer Ptr a. The pointer is not freed when the array is garbage collected. This API is unsafe for the following reasons:

1. The pointer must point to static pinned memory or foreign memory that does not require freeing..
2. The pointer must be legally accessible upto the given length.
3. To guarantee that the array is immutable, the contents of the address must be guaranteed to not change.

Unsafe

Pre-release

Create an Array Word8 of the given length from a static, read only machine address Addr#. See fromPtr for safety caveats.

A common use case for this API is to create an array from a static unboxed string literal. GHC string literals are of type Addr#, and must contain characters that can be encoded in a byte i.e. characters or literal bytes in the range from 0-255.

>>> import Data.Word (Word8)
>>> Array.fromAddr# 5 "hello world!"# :: Array Word8
[104,101,108,108,111]

>>> Array.fromAddr# 3 "\255\NUL\255"# :: Array Word8
[255,0,255]

See also: fromString#

Unsafe

Time complexity: O(1)

Pre-release

Generate a byte array from an Addr# that contains a sequence of NUL (0) terminated bytes. The array would not include the NUL byte. The address must be in static read-only memory and must be legally accessible up to and including the first NUL byte.

An unboxed string literal (e.g. "hello"#) is a common example of an Addr# in static read only memory. It represents the UTF8 encoded sequence of bytes terminated by a NUL byte (a CString) corresponding to the given unicode string.

>>> Array.fromCString# "hello world!"#
[104,101,108,108,111,32,119,111,114,108,100,33]

>>> Array.fromCString# "\255\NUL\255"#
[255]

See also: fromAddr#

Unsafe

Time complexity: O(n) (computes the length of the string)

Pre-release

Create an Array from the first N elements of a list. The array is allocated to size N, if the list terminates before N elements then the array may hold less than N elements.

Since 0.7.0 (Streamly.Memory.Array)

Since: 0.8.0

Create an Array from a list. The list must be of finite size.

Since 0.7.0 (Streamly.Memory.Array)

Since: 0.8.0

Create an Array from the first N elements of a stream. The array is allocated to size N, if the stream terminates before N elements then the array may hold less than N elements.

Pre-release

Create an Array from a stream. This is useful when we want to create a single array from a stream of unknown size. writeN is at least twice as efficient when the size is already known.

Note that if the input stream is too large memory allocation for the array may fail. When the stream size is not known, arraysOf followed by processing of indvidual arrays in the resulting stream should be preferred.

Pre-release

writeN n folds a maximum of n elements from the input stream to an Array.

Since 0.7.0 (Streamly.Memory.Array)

Since: 0.8.0

writeNAligned alignment n folds a maximum of n elements from the input stream to an Array aligned to the given size.

Pre-release

Fold the whole input to a single array.

Caution! Do not use this on infinite streams.

Since 0.7.0 (Streamly.Memory.Array)

Since: 0.8.0

writeLastN n folds a maximum of n elements from the end of the input stream to an Array.

Since: 0.8.0

Convert an Array into a list.

Since 0.7.0 (Streamly.Memory.Array)

Since: 0.8.0

Convert an Array into a stream.

Pre-release

Convert an Array into a stream in reverse order.

Pre-release

Unfold an array into a stream.

Since 0.7.0 (Streamly.Memory.Array)

Since: 0.8.0

Unfold an array into a stream, does not check the end of the array, the user is responsible for terminating the stream within the array bounds. For high performance application where the end condition can be determined by a terminating fold.

Written in the hope that it may be faster than "read", however, in the case for which this was written, "read" proves to be faster even though the core generated with unsafeRead looks simpler.

Pre-release

Unfold an array into a stream in reverse order.

Since: 0.8.0

O(1) Lookup the element at the given index. Index starts from 0.

Since: 0.8.0

Return element at the specified index without checking the bounds.

Like getIndex but indexes the array in reverse from the end.

Pre-release

>>> import qualified Streamly.Internal.Data.Array.Foreign as Array
>>> last arr = Array.getIndexRev arr 0

Pre-release

Given a stream of array indices, read the elements on those indices from the supplied Array. An exception is thrown if an index is out of bounds.

This is the most general operation. We can implement other operations in terms of this:

read =
     let u = lmap (arr -> (0, length arr - 1)) Unfold.enumerateFromTo
      in Unfold.lmap f (getIndices arr)

readRev =
     let i = length arr - 1
      in Unfold.lmap f (getIndicesFromThenTo i (i - 1) 0)

Unimplemented

Unfolds (from, then, to, array) generating a finite stream whose first element is the array value from the index from and the successive elements are from the indices in increments of then up to to. Index enumeration can occur downwards or upwards depending on whether then comes before or after from.

getIndicesFromThenTo =
    let f (from, next, to, arr) =
            (Stream.enumerateFromThenTo from next to, arr)
     in Unfold.lmap f getIndices

Unimplemented

O(1) Get the length of the array i.e. the number of elements in the array.

Since 0.7.0 (Streamly.Memory.Array)

Since: 0.8.0

>>> import qualified Streamly.Internal.Data.Array.Foreign.Type as Array
>>> null arr = Array.byteLength arr == 0

Pre-release

Given a sorted array, perform a binary search to find the given element. Returns the index of the element if found.

Unimplemented

Perform a linear search to find all the indices where a given element is present in an array.

Unimplemented

Cast an array having elements of type a into an array having elements of type b. The length of the array should be a multiple of the size of the target element otherwise Nothing is returned.

Since: 0.8.0

Cast an Array a into an Array Word8.

Since: 0.8.0

Cast an array having elements of type a into an array having elements of type b. The array size must be a multiple of the size of type b otherwise accessing the last element of the array may result into a crash or a random value.

Pre-release

Use an Array a as Ptr b.

Unsafe

Pre-release

Convert an array of any type into a null terminated CString Ptr.

Unsafe

O(n) Time: (creates a copy of the array)

Pre-release

Makes an immutable array using the underlying memory of the mutable array.

Please make sure that there are no other references to the mutable array lying around, so that it is never used after freezing it using unsafeFreeze. If the underlying array is mutated, the immutable promise is lost.

Pre-release

Makes a mutable array using the underlying memory of the immutable array.

Please make sure that there are no other references to the immutable array lying around, so that it is never used after thawing it using unsafeThaw. If the resulting array is mutated, any references to the older immutable array are mutated as well.

Pre-release

O(1) Slice an array in constant time.

Caution: The bounds of the slice are not checked.

Unsafe

Pre-release

Generate a stream of slices of specified length from an array, starting from the supplied array index. The last slice may be shorter than the requested length.

Pre-release/

Split the array into a stream of slices using a predicate. The element matching the predicate is dropped.

Pre-release

Transform an array into another array using a stream transformation operation.

Pre-release

Fold an array using a stream fold operation.

Pre-release

Fold an array using a Fold.

Pre-release