Data.Array.MArray

Copyright	(c) The University of Glasgow 2001
License	BSD-style (see the file libraries/base/LICENSE)
Maintainer	libraries@haskell.org
Stability	experimental
Portability	non-portable (uses Data.Array.Base)
Safe Haskell	Trustworthy
Language	Haskell2010

Class of mutable array types

class Monad m => MArray (a :: Type -> Type -> Type) e (m :: Type -> Type) Source

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.

The Ix class and operations

module Data.Ix

Constructing mutable arrays

newArray :: (MArray a e m, Ix i) => (i, i) -> e -> m (a i e) Source

Builds a new array, with every element initialised to the supplied value. The first and second element of the tuple specifies the lowest and highest index, respectively.

newArray_ :: (MArray a e m, 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. The first and second element of the tuple specifies the lowest and highest index, respectively.

newListArray :: (MArray a e m, Ix i) => (i, i) -> [e] -> m (a i e) Source

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. The first and second element of the tuple specifies the lowest and highest index, respectively.

newGenArray :: (MArray a e m, Ix i) => (i, i) -> (i -> m e) -> m (a i e) Source

Constructs a mutable array using a generator function. It invokes the generator function in ascending order of the indices.

Since: array-0.5.6.0

Reading and writing mutable arrays

readArray :: (MArray a e m, Ix i) => a i e -> i -> m e Source

Read an element from a mutable array

writeArray :: (MArray a e m, Ix i) => a i e -> i -> e -> m () Source

Write an element in a mutable array

modifyArray :: (MArray a e m, Ix i) => a i e -> i -> (e -> e) -> m () Source

Modify an element in a mutable array

Since: array-0.5.6.0

modifyArray' :: (MArray a e m, Ix i) => a i e -> i -> (e -> e) -> m () Source

Modify an element in a mutable array. Strict in the written element.

Since: array-0.5.6.0

Array folds

foldlMArray' :: (MArray a e m, Ix i) => (b -> e -> b) -> b -> a i e -> m b Source

Strict accumulating left-associative fold.

Since: array-0.5.8.0

foldrMArray' :: (MArray a e m, Ix i) => (e -> b -> b) -> b -> a i e -> m b Source

Strict accumulating right-associative fold.

Since: array-0.5.8.0

mapMArrayM_ :: (MArray a e m, Ix i) => (e -> m b) -> a i e -> m () Source

Map elements to monadic actions, sequence them left-to-right, and discard the results.

Since: array-0.5.8.0

forMArrayM_ :: (MArray a e m, Ix i) => a i e -> (e -> m b) -> m () Source

forMArrayM_ is mapMArrayM_ with its arguments flipped.

Since: array-0.5.8.0

foldlMArrayM' :: (MArray a e m, Ix i) => (b -> e -> m b) -> b -> a i e -> m b Source

Strict accumulating left-associative monadic fold.

Since: array-0.5.8.0

foldrMArrayM' :: (MArray a e m, Ix i) => (e -> b -> m b) -> b -> a i e -> m b Source

Strict accumulating right-associative monadic fold.

Since: array-0.5.8.0

Derived arrays

mapArray :: (MArray a e' m, MArray a e m, Ix i) => (e' -> e) -> a i e' -> m (a i e) Source

Constructs a new array derived from the original array by applying a function to each of the elements.

mapIndices :: (MArray a e m, Ix i, Ix j) => (i, i) -> (i -> j) -> a j e -> m (a i e) Source

Constructs a new array derived from the original array by applying a function to each of the indices.

Deconstructing mutable arrays

getBounds :: (MArray a e m, Ix i) => a i e -> m (i, i) Source

Returns the bounds of the array (lowest,highest).

getElems :: (MArray a e m, Ix i) => a i e -> m [e] Source

Return a list of all the elements of a mutable array

getAssocs :: (MArray a e m, Ix i) => a i e -> m [(i, e)] Source

Return a list of all the associations of a mutable array, in index order.

Conversions between mutable and immutable arrays

freeze :: (Ix i, MArray a e m, IArray b e) => a i e -> m (b i e) Source

Converts a mutable array (any instance of MArray) to an immutable array (any instance of IArray) by taking a complete copy of it.

thaw :: (Ix i, IArray a e, MArray b e m) => a i e -> m (b i e) Source

Converts an immutable array (any instance of IArray) into a mutable array (any instance of MArray) by taking a complete copy of it.