{-# 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). -- ----------------------------------------------------------------------------- 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 Prelude import GHC.Arr