Haskell Code by HsColour

-----------------------------------------------------------------------------
-- |
-- Module : Data.Ix
-- Copyright : (c) The University of Glasgow 2001
-- License : BSD-style (see the file libraries/base/LICENSE)
-- 
-- Maintainer : libraries@haskell.org
-- Stability : stable
-- Portability : portable
--
-- The 'Ix' class is used to map a contiguous subrange of values in
-- type onto integers. It is used primarily for array indexing
-- (see the array package).
-- 
-----------------------------------------------------------------------------
module Data.Ix
 (
 -- * The 'Ix' class
 Ix
 ( range -- :: (Ix a) => (a,a) -> [a]
 , index -- :: (Ix a) => (a,a) -> a -> Int
 , inRange -- :: (Ix a) => (a,a) -> a -> Bool
 , rangeSize -- :: (Ix a) => (a,a) -> Int
 )
 -- Ix instances:
 --
 -- Ix Char
 -- Ix Int
 -- Ix Integer
 -- Ix Bool
 -- Ix Ordering
 -- Ix ()
 -- (Ix a, Ix b) => Ix (a, b)
 -- ...

 -- Implementation checked wrt. Haskell 98 lib report, 1/99.

 -- * Deriving Instances of 'Ix'
 -- | Derived instance declarations for the class 'Ix' are only possible
 -- for enumerations (i.e. datatypes having only nullary constructors)
 -- and single-constructor datatypes, including arbitrarily large tuples,
 -- whose constituent types are instances of 'Ix'. 
 -- 
 -- * For an enumeration, the nullary constructors are assumed to be
 -- numbered left-to-right with the indices being 0 to n-1 inclusive. This
 -- is the same numbering defined by the 'Enum' class. For example, given
 -- the datatype: 
 -- 
 -- > data Colour = Red | Orange | Yellow | Green | Blue | Indigo | Violet
 -- 
 -- we would have: 
 -- 
 -- > range (Yellow,Blue) == [Yellow,Green,Blue]
 -- > index (Yellow,Blue) Green == 1
 -- > inRange (Yellow,Blue) Red == False
 -- 
 -- * For single-constructor datatypes, the derived instance declarations
 -- are as shown for tuples in Figure 1
 -- <http://www.haskell.org/onlinelibrary/ix.html#prelude-index>.

 ) where

import Prelude

#ifdef __GLASGOW_HASKELL__
import GHC.Arr
#endif

#ifdef __HUGS__
import Hugs.Prelude( Ix(..) )
#endif

#ifdef __NHC__
import Ix (Ix(..))
#endif