array-0.5.2.0: Mutable and immutable arrays

Copyright (c) The University of Glasgow 2001 BSD-style (see the file libraries/base/LICENSE) libraries@haskell.org experimental non-portable (uses Data.Array.Base) None Haskell2010

Data.Array.MArray

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.

Synopsis

# Class of mutable array types

class Monad m => MArray a e m 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.

Minimal complete definition

getBounds, getNumElements, unsafeRead, unsafeWrite

Instances

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.

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.

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.

# 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

# 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

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.