base-4.8.0.0: Basic libraries

Copyright(c) The University of Glasgow 2001
LicenseBSD-style (see the file libraries/base/LICENSE)
Maintainerlibraries@haskell.org
Stabilitystable
Portabilityportable
Safe HaskellTrustworthy
LanguageHaskell2010

Data.Ix

Contents

Description

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.

Synopsis

The Ix class

class Ord a => Ix a where Source

The Ix class is used to map a contiguous subrange of values in a type onto integers. It is used primarily for array indexing (see the array package).

The first argument (l,u) of each of these operations is a pair specifying the lower and upper bounds of a contiguous subrange of values.

An implementation is entitled to assume the following laws about these operations:

Minimal complete definition

range, (index | unsafeIndex), inRange

Methods

range :: (a, a) -> [a] Source

The list of values in the subrange defined by a bounding pair.

index :: (a, a) -> a -> Int Source

The position of a subscript in the subrange.

inRange :: (a, a) -> a -> Bool Source

Returns True the given subscript lies in the range defined the bounding pair.

rangeSize :: (a, a) -> Int Source

The size of the subrange defined by a bounding pair.

Instances

Ix Bool Source 
Ix Char Source 
Ix Int Source 
Ix Int8 Source 
Ix Int16 Source 
Ix Int32 Source 
Ix Int64 Source 
Ix Integer Source 
Ix Ordering Source 
Ix Word Source 
Ix Word8 Source 
Ix Word16 Source 
Ix Word32 Source 
Ix Word64 Source 
Ix () Source 
Ix GeneralCategory Source 
Ix SeekMode Source 
Ix IOMode Source 
Ix Natural Source 
Ix Void Source 
(Ix a, Ix b) => Ix (a, b) Source 
Ix (Proxy k s) Source 
(Ix a1, Ix a2, Ix a3) => Ix (a1, a2, a3) Source 
(Ix a1, Ix a2, Ix a3, Ix a4) => Ix (a1, a2, a3, a4) Source 
(Ix a1, Ix a2, Ix a3, Ix a4, Ix a5) => Ix (a1, a2, a3, a4, a5) Source 

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