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|
{-# LANGUAGE Trustworthy #-}
-----------------------------------------------------------------------------
-- |
-- 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). 'Ix' uses row-major order.
--
-----------------------------------------------------------------------------
module Data.Ix
(
-- * The 'Ix' class
Ix
( range
, index
, inRange
, rangeSize
)
-- Ix instances:
--
-- Ix Char
-- Ix Int
-- Ix Integer
-- Ix Bool
-- Ix Ordering
-- Ix ()
-- (Ix a, Ix b) => Ix (a, b)
-- ...
-- * 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 GHC.Arr
|
