1 % -----------------------------------------------------------------------------
2 % $Id: Array.lhs,v 1.16 2001/04/14 22:27:00 qrczak 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 ------------ GHC --------------------
48 import PrelArr -- Most of the hard work is done here
49 ------------ End of GHC --------------------
55 ------------ HUGS (rest of file) --------------------
56 import PrelPrim ( PrimArray
61 , primUnsafeFreezeArray
71 %*********************************************************
73 \subsection{The Array type}
75 %*********************************************************
79 data Array ix elt = Array (ix,ix) (PrimArray elt)
81 array :: Ix a => (a,a) -> [(a,b)] -> Array a b
82 array ixs@(ix_start, ix_end) ivs = runST (do
83 { mut_arr <- primNewArray (rangeSize ixs) arrEleBottom
84 ; mapM_ (\ (i,v) -> primWriteArray mut_arr (index ixs i) v) ivs
85 ; arr <- primUnsafeFreezeArray mut_arr
86 ; return (Array ixs arr)
90 arrEleBottom = error "(Array.!): undefined array element"
92 listArray :: Ix a => (a,a) -> [b] -> Array a b
93 listArray b vs = array b (zipWith (\ a b -> (a,b)) (range b) vs)
95 (!) :: Ix a => Array a b -> a -> b
96 (Array bounds arr) ! i = primIndexArray arr (index bounds i)
98 bounds :: Ix a => Array a b -> (a,a)
99 bounds (Array b _) = b
101 indices :: Ix a => Array a b -> [a]
102 indices = range . bounds
104 elems :: Ix a => Array a b -> [b]
105 elems a = [a!i | i <- indices a]
107 assocs :: Ix a => Array a b -> [(a,b)]
108 assocs a = [(i, a!i) | i <- indices a]
110 (//) :: Ix a => Array a b -> [(a,b)] -> Array a b
111 (//) a us = array (bounds a)
112 ([(i,a!i) | i <- indices a \\ [i | (i,_) <- us]]
115 accum :: Ix a => (b -> c -> b) -> Array a b -> [(a,c)] -> Array a b
116 accum f = foldl (\a (i,v) -> a // [(i,f (a!i) v)])
118 accumArray :: Ix a => (b -> c -> b) -> b -> (a,a) -> [(a,c)] -> Array a b
119 accumArray f z b = accum f (array b [(i,z) | i <- range b])
121 ixmap :: (Ix a, Ix b) => (a,a) -> (a -> b) -> Array b c -> Array a c
122 ixmap b f a = array b [(i, a ! f i) | i <- range b]
125 instance (Ix a) => Functor (Array a) where
126 fmap f a = array (bounds a) [(i, f(a!i)) | i <- indices a]
128 instance (Ix a, Eq b) => Eq (Array a b) where
129 a == a' = assocs a == assocs a'
131 instance (Ix a, Ord b) => Ord (Array a b) where
132 a <= a' = assocs a <= assocs a'
135 instance (Ix a, Show a, Show b) => Show (Array a b) where
136 showsPrec p a = showParen (p > 9) (
137 showString "array " .
138 shows (bounds a) . showChar ' ' .
141 instance (Ix a, Read a, Read b) => Read (Array a b) where
142 readsPrec p = readParen (p > 9)
143 (\r -> [(array b as, u) | ("array",s) <- lex r,