
GHC.Arr  Portability  nonportable (GHC extensions)  Stability  internal  Maintainer  cvsghc@haskell.org 



Description 
GHC's array implementation.


Synopsis 

class Ord a => Ix a where    indexError :: Show a => (a, a) > a > String > b   type IPr = (Int, Int)   data Ix i => Array i e = Array !i !i !Int (Array# e)   data STArray s i e = STArray !i !i !Int (MutableArray# s e)   arrEleBottom :: a   array :: Ix i => (i, i) > [(i, e)] > Array i e   unsafeArray :: Ix i => (i, i) > [(Int, e)] > Array i e   unsafeArray' :: Ix i => (i, i) > Int > [(Int, e)] > Array i e   fill :: MutableArray# s e > (Int, e) > STRep s a > STRep s a   done :: Ix i => i > i > Int > MutableArray# s e > STRep s (Array i e)   listArray :: Ix i => (i, i) > [e] > Array i e   (!) :: Ix i => Array i e > i > e   safeRangeSize :: Ix i => (i, i) > Int   safeIndex :: Ix i => (i, i) > Int > i > Int   unsafeAt :: Ix i => Array i e > Int > e   bounds :: Ix i => Array i e > (i, i)   numElements :: Ix i => Array i e > Int   indices :: Ix i => Array i e > [i]   elems :: Ix i => Array i e > [e]   assocs :: Ix i => Array i e > [(i, e)]   accumArray :: Ix i => (e > a > e) > e > (i, i) > [(i, a)] > Array i e   unsafeAccumArray :: Ix i => (e > a > e) > e > (i, i) > [(Int, a)] > Array i e   unsafeAccumArray' :: Ix i => (e > a > e) > e > (i, i) > Int > [(Int, a)] > Array i e   adjust :: (e > a > e) > MutableArray# s e > (Int, a) > STRep s b > STRep s b   (//) :: Ix i => Array i e > [(i, e)] > Array i e   unsafeReplace :: Ix i => Array i e > [(Int, e)] > Array i e   accum :: Ix i => (e > a > e) > Array i e > [(i, a)] > Array i e   unsafeAccum :: Ix i => (e > a > e) > Array i e > [(Int, a)] > Array i e   amap :: Ix i => (a > b) > Array i a > Array i b   ixmap :: (Ix i, Ix j) => (i, i) > (i > j) > Array j e > Array i e   eqArray :: (Ix i, Eq e) => Array i e > Array i e > Bool   cmpArray :: (Ix i, Ord e) => Array i e > Array i e > Ordering   cmpIntArray :: Ord e => Array Int e > Array Int e > Ordering   newSTArray :: Ix i => (i, i) > e > ST s (STArray s i e)   boundsSTArray :: STArray s i e > (i, i)   numElementsSTArray :: STArray s i e > Int   readSTArray :: Ix i => STArray s i e > i > ST s e   unsafeReadSTArray :: Ix i => STArray s i e > Int > ST s e   writeSTArray :: Ix i => STArray s i e > i > e > ST s ()   unsafeWriteSTArray :: Ix i => STArray s i e > Int > e > ST s ()   freezeSTArray :: Ix i => STArray s i e > ST s (Array i e)   unsafeFreezeSTArray :: Ix i => STArray s i e > ST s (Array i e)   thawSTArray :: Ix i => Array i e > ST s (STArray s i e)   unsafeThawSTArray :: Ix i => Array i e > ST s (STArray s i e) 


Documentation 


The Ix class is used to map a contiguous subrange of values in
a type onto integers. It is used primarily for array indexing
(see the array package).
The first argument (l,u) of each of these operations is a pair
specifying the lower and upper bounds of a contiguous subrange of values.
An implementation is entitled to assume the following laws about these
operations:
inRange (l,u) i == elem i (range (l,u))  range (l,u) !! index (l,u) i == i, when inRange (l,u) i
map (index (l,u)) (range (l,u))) == [0..rangeSize (l,u)1] rangeSize (l,u) == length (range (l,u))
Minimal complete instance: range, index and inRange.
  Methods   The list of values in the subrange defined by a bounding pair.
   The position of a subscript in the subrange.
   Like index, but without checking that the value is in range.
   Returns True the given subscript lies in the range defined
the bounding pair.
   The size of the subrange defined by a bounding pair.
   like rangeSize, but without checking that the upper bound is
in range.

  Instances  Ix Bool  Ix Char  Ix Int  Ix Int8  Ix Int16  Ix Int32  Ix Int64  Ix Integer  Ix Ordering  Ix Word  Ix Word8  Ix Word16  Ix Word32  Ix Word64  Ix ()  Ix IOMode  Ix GeneralCategory  Ix SeekMode  (Ix a, Ix b) => Ix ((,) a b)  (Ix a1, Ix a2, Ix a3) => Ix ((,,) a1 a2 a3)  (Ix a1, Ix a2, Ix a3, Ix a4) => Ix ((,,,) a1 a2 a3 a4)  (Ix a1, Ix a2, Ix a3, Ix a4, Ix a5) => Ix ((,,,,) a1 a2 a3 a4 a5) 








The type of immutable nonstrict (boxed) arrays
with indices in i and elements in e.
The Int is the number of elements in the Array.
 Constructors   Instances  



Mutable, boxed, nonstrict arrays in the ST monad. The type
arguments are as follows:
 s: the state variable argument for the ST type
 i: the index type of the array (should be an instance of Ix)
 e: the element type of the array.
 Constructors   Instances  





:: Ix i   => (i, i)  a pair of bounds, each of the index type
of the array. These bounds are the lowest and
highest indices in the array, in that order.
For example, a oneorigin vector of length
'10' has bounds '(1,10)', and a oneorigin '10'
by '10' matrix has bounds '((1,1),(10,10))'.
 > [(i, e)]  a list of associations of the form
(index, value). Typically, this list will
be expressed as a comprehension. An
association '(i, x)' defines the value of
the array at index i to be x.
 > Array i e   Construct an array with the specified bounds and containing values
for given indices within these bounds.
The array is undefined (i.e. bottom) if any index in the list is
out of bounds. The Haskell 98 Report further specifies that if any
two associations in the list have the same index, the value at that
index is undefined (i.e. bottom). However in GHC's implementation,
the value at such an index is the value part of the last association
with that index in the list.
Because the indices must be checked for these errors, array is
strict in the bounds argument and in the indices of the association
list, but nonstrict in the values. Thus, recurrences such as the
following are possible:
a = array (1,100) ((1,1) : [(i, i * a!(i1))  i < [2..100]])
Not every index within the bounds of the array need appear in the
association list, but the values associated with indices that do not
appear will be undefined (i.e. bottom).
If, in any dimension, the lower bound is greater than the upper bound,
then the array is legal, but empty. Indexing an empty array always
gives an arraybounds error, but bounds still yields the bounds
with which the array was constructed.












Construct an array from a pair of bounds and a list of values in
index order.



The value at the given index in an array.









The bounds with which an array was constructed.



The number of elements in the array.



The list of indices of an array in ascending order.



The list of elements of an array in index order.



The list of associations of an array in index order.



:: Ix i   => e > a > e  accumulating function
 > e  initial value
 > (i, i)  bounds of the array
 > [(i, a)]  association list
 > Array i e   The accumArray deals with repeated indices in the association
list using an accumulating function which combines the values of
associations with the same index.
For example, given a list of values of some index type, hist
produces a histogram of the number of occurrences of each index within
a specified range:
hist :: (Ix a, Num b) => (a,a) > [a] > Array a b
hist bnds is = accumArray (+) 0 bnds [(i, 1)  i<is, inRange bnds i]
If the accumulating function is strict, then accumArray is strict in
the values, as well as the indices, in the association list. Thus,
unlike ordinary arrays built with array, accumulated arrays should
not in general be recursive.



unsafeAccumArray :: Ix i => (e > a > e) > e > (i, i) > [(Int, a)] > Array i e  Source 


unsafeAccumArray' :: Ix i => (e > a > e) > e > (i, i) > Int > [(Int, a)] > Array i e  Source 





Constructs an array identical to the first argument except that it has
been updated by the associations in the right argument.
For example, if m is a 1origin, n by n matrix, then
m//[((i,i), 0)  i < [1..n]]
is the same matrix, except with the diagonal zeroed.
Repeated indices in the association list are handled as for array:
Haskell 98 specifies that the resulting array is undefined (i.e. bottom),
but GHC's implementation uses the last association for each index.





accum f takes an array and an association list and accumulates
pairs from the list into the array with the accumulating function f.
Thus accumArray can be defined using accum:
accumArray f z b = accum f (array b [(i, z)  i < range b])







ixmap allows for transformations on array indices.
It may be thought of as providing function composition on the right
with the mapping that the original array embodies.
A similar transformation of array values may be achieved using fmap
from the Array instance of the Functor class.






























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