1 % -----------------------------------------------------------------------------
2 % $Id: Array.lhs,v 1.13 2000/06/30 13:39:35 simonmar Exp $
4 % (c) The University of Glasgow, 1994-2000
6 \section[Array]{Module @Array@}
9 {-# OPTIONS -fno-implicit-prelude #-}
14 module Ix -- export all of Ix
15 , Array -- Array type is abstract
17 , array -- :: (Ix a) => (a,a) -> [(a,b)] -> Array a b
18 , listArray -- :: (Ix a) => (a,a) -> [b] -> Array a b
19 , (!) -- :: (Ix a) => Array a b -> a -> b
20 , bounds -- :: (Ix a) => Array a b -> (a,a)
21 , indices -- :: (Ix a) => Array a b -> [a]
22 , elems -- :: (Ix a) => Array a b -> [b]
23 , assocs -- :: (Ix a) => Array a b -> [(a,b)]
24 , accumArray -- :: (Ix a) => (b -> c -> b) -> b -> (a,a) -> [(a,c)] -> Array a b
25 , (//) -- :: (Ix a) => Array a b -> [(a,b)] -> Array a b
26 , accum -- :: (Ix a) => (b -> c -> b) -> Array a b -> [(a,c)] -> Array a b
27 , ixmap -- :: (Ix a, Ix b) => (a,a) -> (a -> b) -> Array b c -> Array a b
31 -- Ix a => Functor (Array a)
32 -- (Ix a, Eq b) => Eq (Array a b)
33 -- (Ix a, Ord b) => Ord (Array a b)
34 -- (Ix a, Show a, Show b) => Show (Array a b)
35 -- (Ix a, Read a, Read b) => Read (Array a b)
38 -- Implementation checked wrt. Haskell 98 lib report, 1/99.
46 import PrelArr -- Most of the hard work is done here
49 import PrelPrim ( PrimArray
54 , primUnsafeFreezeArray
67 %*********************************************************
69 \subsection{Definitions of array, !, bounds}
71 %*********************************************************
76 {-# SPECIALISE listArray :: (Int,Int) -> [b] -> Array Int b #-}
77 listArray :: (Ix a) => (a,a) -> [b] -> Array a b
78 listArray b vs = array b (zip (range b) vs)
81 elems :: (Ix a) => Array a b -> [b]
82 elems a = [a!i | i <- indices a]
84 ixmap :: (Ix a, Ix b) => (a,a) -> (a -> b) -> Array b c -> Array a c
85 ixmap b f a = array b [(i, a ! f i) | i <- range b]
89 %*********************************************************
91 \subsection{Instance declarations for Array type}
93 %*********************************************************
98 data Array ix elt = Array (ix,ix) (PrimArray elt)
100 array :: Ix a => (a,a) -> [(a,b)] -> Array a b
101 array ixs@(ix_start, ix_end) ivs = runST (do
102 { mut_arr <- primNewArray (rangeSize ixs) arrEleBottom
103 ; mapM_ (\ (i,v) -> primWriteArray mut_arr (index ixs i) v) ivs
104 ; arr <- primUnsafeFreezeArray mut_arr
105 ; return (Array ixs arr)
109 arrEleBottom = error "(Array.!): undefined array element"
111 listArray :: Ix a => (a,a) -> [b] -> Array a b
112 listArray b vs = array b (zipWith (\ a b -> (a,b)) (range b) vs)
114 (!) :: Ix a => Array a b -> a -> b
115 (Array bounds arr) ! i = primIndexArray arr (index bounds i)
117 bounds :: Ix a => Array a b -> (a,a)
118 bounds (Array b _) = b
120 indices :: Ix a => Array a b -> [a]
121 indices = range . bounds
123 elems :: Ix a => Array a b -> [b]
124 elems a = [a!i | i <- indices a]
126 assocs :: Ix a => Array a b -> [(a,b)]
127 assocs a = [(i, a!i) | i <- indices a]
129 (//) :: Ix a => Array a b -> [(a,b)] -> Array a b
130 a // us = array (bounds a)
131 ([(i,a!i) | i <- indices a \\ [i | (i,_) <- us]]
134 accum :: Ix a => (b -> c -> b) -> Array a b -> [(a,c)] -> Array a b
135 accum f = foldl (\a (i,v) -> a // [(i,f (a!i) v)])
137 accumArray :: Ix a => (b -> c -> b) -> b -> (a,a) -> [(a,c)] -> Array a b
138 accumArray f z b = accum f (array b [(i,z) | i <- range b])
140 ixmap :: (Ix a, Ix b) => (a,a) -> (a -> b) -> Array b c -> Array a c
141 ixmap b f a = array b [(i, a ! f i) | i <- range b]
144 instance (Ix a) => Functor (Array a) where
145 fmap f a = array (bounds a) [(i, f(a!i)) | i <- indices a]
147 instance (Ix a, Eq b) => Eq (Array a b) where
148 a == a' = assocs a == assocs a'
150 instance (Ix a, Ord b) => Ord (Array a b) where
151 a <= a' = assocs a <= assocs a'
154 instance (Ix a, Show a, Show b) => Show (Array a b) where
155 showsPrec p a = showParen (p > 9) (
156 showString "array " .
157 shows (bounds a) . showChar ' ' .
160 instance (Ix a, Read a, Read b) => Read (Array a b) where
161 readsPrec p = readParen (p > 9)
162 (\r -> [(array b as, u) | ("array",s) <- lex r,