base-4.18.0.0: Basic libraries

Data.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

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

Instances details
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
       range   (Yellow,Blue)        ==  [Yellow,Green,Blue]
inRange (Yellow,Blue) Red    ==  False