Copyright	(c) The University of Glasgow 2001
License	BSD-style (see the file libraries/base/LICENSE)
Maintainer	libraries@haskell.org
Stability	stable
Portability	portable
Safe Haskell	Trustworthy
Language	Haskell2010

Data.Ix

Contents

The Ix class
Deriving Instances of Ix

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:

inRange (l,u) i == elem i (range (l,u))
range (l,u) !! index (l,u) i == i, when inRange (l,u) i
map (index (l,u)) (range (l,u))) == [0..rangeSize (l,u)-1]
rangeSize (l,u) == length (range (l,u))

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

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.

The Ix class

Deriving Instances of Ix

The `Ix` class

Deriving Instances of `Ix`