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| Data.Array.MArray | | Portability | non-portable (uses Data.Array.Base) | | Stability | experimental | | Maintainer | libraries@haskell.org |
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| Description |
| An overloaded interface to mutable arrays. For array types which can be
used with this interface, see Data.Array.IO, Data.Array.ST,
and Data.Array.Storable.
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| Synopsis |
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| class Monad m => MArray a e m where | | | | module Data.Ix | | | newArray :: (MArray a e m, Ix i) => (i, i) -> e -> m (a i e) | | | newArray_ :: (MArray a e m, Ix i) => (i, i) -> m (a i e) | | | newListArray :: (MArray a e m, Ix i) => (i, i) -> [e] -> m (a i e) | | | readArray :: (MArray a e m, Ix i) => a i e -> i -> m e | | | writeArray :: (MArray a e m, Ix i) => a i e -> i -> e -> m () | | | mapArray :: (MArray a e' m, MArray a e m, Ix i) => (e' -> e) -> a i e' -> m (a i e) | | | mapIndices :: (MArray a e m, Ix i, Ix j) => (i, i) -> (i -> j) -> a j e -> m (a i e) | | | getBounds :: (MArray a e m, Ix i) => a i e -> m (i, i) | | | getElems :: (MArray a e m, Ix i) => a i e -> m [e] | | | getAssocs :: (MArray a e m, Ix i) => a i e -> m [(i, e)] | | | freeze :: (Ix i, MArray a e m, IArray b e) => a i e -> m (b i e) | | | unsafeFreeze :: (Ix i, MArray a e m, IArray b e) => a i e -> m (b i e) | | | thaw :: (Ix i, IArray a e, MArray b e m) => a i e -> m (b i e) | | | unsafeThaw :: (Ix i, IArray a e, MArray b e m) => a i e -> m (b i e) |
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| Class of mutable array types
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Class of mutable array types.
An array type has the form (a i e) where a is the array type
constructor (kind * -> * -> *), i is the index type (a member of
the class Ix), and e is the element type.
The MArray class is parameterised over both a and e (so that
instances specialised to certain element types can be defined, in the
same way as for IArray), and also over the type of the monad, m,
in which the mutable array will be manipulated.
| | | Methods | | getBounds :: Ix i => a i e -> m (i, i) | Source |
| | Returns the bounds of the array
| | | newArray :: Ix i => (i, i) -> e -> m (a i e) | Source |
| | Builds a new array, with every element initialised to the supplied
value.
| | | newArray_ :: Ix i => (i, i) -> m (a i e) | Source |
| | Builds a new array, with every element initialised to an
undefined value. In a monadic context in which operations must
be deterministic (e.g. the ST monad), the array elements are
initialised to a fixed but undefined value, such as zero.
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| |  Instances | |
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| The Ix class and operations
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| module Data.Ix |
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| Constructing mutable arrays
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| Builds a new array, with every element initialised to the supplied
value.
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| Builds a new array, with every element initialised to an
undefined value. In a monadic context in which operations must
be deterministic (e.g. the ST monad), the array elements are
initialised to a fixed but undefined value, such as zero.
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| newListArray :: (MArray a e m, Ix i) => (i, i) -> [e] -> m (a i e) | Source |
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| Constructs a mutable array from a list of initial elements.
The list gives the elements of the array in ascending order
beginning with the lowest index.
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| Reading and writing mutable arrays
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| Read an element from a mutable array
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| Write an element in a mutable array
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| Derived arrays
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| Constructs a new array derived from the original array by applying a
function to each of the elements.
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| mapIndices :: (MArray a e m, Ix i, Ix j) => (i, i) -> (i -> j) -> a j e -> m (a i e) | Source |
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| Constructs a new array derived from the original array by applying a
function to each of the indices.
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| Deconstructing mutable arrays
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| Returns the bounds of the array
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| Return a list of all the elements of a mutable array
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| Return a list of all the associations of a mutable array, in
index order.
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| Conversions between mutable and immutable arrays
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| Converts a mutable array (any instance of MArray) to an
immutable array (any instance of IArray) by taking a complete
copy of it.
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Converts an mutable array into an immutable array. The
implementation may either simply cast the array from
one type to the other without copying the array, or it
may take a full copy of the array.
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 mutable version is never modified after the freeze operation.
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
specialisations, you will need to compile with optimisation (-O) to
get them.
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| Converts an immutable array (any instance of IArray) into a
mutable array (any instance of MArray) by taking a complete copy
of it.
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Converts an immutable array into a mutable array. The
implementation may either simply cast the array from
one type to the other without copying the array, or it
may take a full copy of the array.
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 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 unsafeThawwriteunsafeFreeze
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
unsafeThaw. Because the optimised versions are enabled by
specialisations, you will need to compile with optimisation (-O) to
get them.
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| Produced by Haddock version 0.9 |
