{-# LANGUAGE Safe #-}

-- |
--
-- 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),
     -- *  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 chapter 19, section 2 of the Haskell 2010 report:
     -- <https://www.haskell.org/onlinereport/haskell2010/haskellch19.html>.
     ) where

import GHC.Internal.Data.Ix
