Safe Haskell	Safe
Language	Haskell2010

Data.Ix

Contents

The Ix class
Deriving Instances of Ix

Synopsis

class Ord a => Ix a where
- range :: (a, a) -> [a]
- index :: (a, a) -> a -> Int
- inRange :: (a, a) -> a -> Bool
- rangeSize :: (a, a) -> Int

The `Ix` class

class Ord a => Ix a where #

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] #

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

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

The position of a subscript in the subrange.

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

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

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

The size of the subrange defined by a bounding pair.

Instances

Ix Bool	Since: base-2.1
Instance details Defined in GHC.Arr Methods range :: (Bool, Bool) -> [Bool] # index :: (Bool, Bool) -> Bool -> Int # unsafeIndex :: (Bool, Bool) -> Bool -> Int inRange :: (Bool, Bool) -> Bool -> Bool # rangeSize :: (Bool, Bool) -> Int # unsafeRangeSize :: (Bool, Bool) -> Int
Ix Char	Since: base-2.1
Instance details Defined in GHC.Arr Methods range :: (Char, Char) -> [Char] # index :: (Char, Char) -> Char -> Int # unsafeIndex :: (Char, Char) -> Char -> Int inRange :: (Char, Char) -> Char -> Bool # rangeSize :: (Char, Char) -> Int # unsafeRangeSize :: (Char, Char) -> Int
Ix Int	Since: base-2.1
Instance details Defined in GHC.Arr Methods range :: (Int, Int) -> [Int] # index :: (Int, Int) -> Int -> Int # unsafeIndex :: (Int, Int) -> Int -> Int inRange :: (Int, Int) -> Int -> Bool # rangeSize :: (Int, Int) -> Int # unsafeRangeSize :: (Int, Int) -> Int
Ix Int8	Since: base-2.1
Instance details Defined in GHC.Int Methods range :: (Int8, Int8) -> [Int8] # index :: (Int8, Int8) -> Int8 -> Int # unsafeIndex :: (Int8, Int8) -> Int8 -> Int inRange :: (Int8, Int8) -> Int8 -> Bool # rangeSize :: (Int8, Int8) -> Int # unsafeRangeSize :: (Int8, Int8) -> Int
Ix Int16	Since: base-2.1
Instance details Defined in GHC.Int Methods range :: (Int16, Int16) -> [Int16] # index :: (Int16, Int16) -> Int16 -> Int # unsafeIndex :: (Int16, Int16) -> Int16 -> Int inRange :: (Int16, Int16) -> Int16 -> Bool # rangeSize :: (Int16, Int16) -> Int # unsafeRangeSize :: (Int16, Int16) -> Int
Ix Int32	Since: base-2.1
Instance details Defined in GHC.Int Methods range :: (Int32, Int32) -> [Int32] # index :: (Int32, Int32) -> Int32 -> Int # unsafeIndex :: (Int32, Int32) -> Int32 -> Int inRange :: (Int32, Int32) -> Int32 -> Bool # rangeSize :: (Int32, Int32) -> Int # unsafeRangeSize :: (Int32, Int32) -> Int
Ix Int64	Since: base-2.1
Instance details Defined in GHC.Int Methods range :: (Int64, Int64) -> [Int64] # index :: (Int64, Int64) -> Int64 -> Int # unsafeIndex :: (Int64, Int64) -> Int64 -> Int inRange :: (Int64, Int64) -> Int64 -> Bool # rangeSize :: (Int64, Int64) -> Int # unsafeRangeSize :: (Int64, Int64) -> Int
Ix Integer	Since: base-2.1
Instance details Defined in GHC.Arr Methods range :: (Integer, Integer) -> [Integer] # index :: (Integer, Integer) -> Integer -> Int # unsafeIndex :: (Integer, Integer) -> Integer -> Int inRange :: (Integer, Integer) -> Integer -> Bool # rangeSize :: (Integer, Integer) -> Int # unsafeRangeSize :: (Integer, Integer) -> Int
Ix Natural	Since: base-4.8.0.0
Instance details Defined in GHC.Arr Methods range :: (Natural, Natural) -> [Natural] # index :: (Natural, Natural) -> Natural -> Int # unsafeIndex :: (Natural, Natural) -> Natural -> Int inRange :: (Natural, Natural) -> Natural -> Bool # rangeSize :: (Natural, Natural) -> Int # unsafeRangeSize :: (Natural, Natural) -> Int
Ix Ordering	Since: base-2.1
Instance details Defined in GHC.Arr Methods range :: (Ordering, Ordering) -> [Ordering] # index :: (Ordering, Ordering) -> Ordering -> Int # unsafeIndex :: (Ordering, Ordering) -> Ordering -> Int inRange :: (Ordering, Ordering) -> Ordering -> Bool # rangeSize :: (Ordering, Ordering) -> Int # unsafeRangeSize :: (Ordering, Ordering) -> Int
Ix Word	Since: base-4.6.0.0
Instance details Defined in GHC.Arr Methods range :: (Word, Word) -> [Word] # index :: (Word, Word) -> Word -> Int # unsafeIndex :: (Word, Word) -> Word -> Int inRange :: (Word, Word) -> Word -> Bool # rangeSize :: (Word, Word) -> Int # unsafeRangeSize :: (Word, Word) -> Int
Ix Word8	Since: base-2.1
Instance details Defined in GHC.Word Methods range :: (Word8, Word8) -> [Word8] # index :: (Word8, Word8) -> Word8 -> Int # unsafeIndex :: (Word8, Word8) -> Word8 -> Int inRange :: (Word8, Word8) -> Word8 -> Bool # rangeSize :: (Word8, Word8) -> Int # unsafeRangeSize :: (Word8, Word8) -> Int
Ix Word16	Since: base-2.1
Instance details Defined in GHC.Word Methods range :: (Word16, Word16) -> [Word16] # index :: (Word16, Word16) -> Word16 -> Int # unsafeIndex :: (Word16, Word16) -> Word16 -> Int inRange :: (Word16, Word16) -> Word16 -> Bool # rangeSize :: (Word16, Word16) -> Int # unsafeRangeSize :: (Word16, Word16) -> Int
Ix Word32	Since: base-2.1
Instance details Defined in GHC.Word Methods range :: (Word32, Word32) -> [Word32] # index :: (Word32, Word32) -> Word32 -> Int # unsafeIndex :: (Word32, Word32) -> Word32 -> Int inRange :: (Word32, Word32) -> Word32 -> Bool # rangeSize :: (Word32, Word32) -> Int # unsafeRangeSize :: (Word32, Word32) -> Int
Ix Word64	Since: base-2.1
Instance details Defined in GHC.Word Methods range :: (Word64, Word64) -> [Word64] # index :: (Word64, Word64) -> Word64 -> Int # unsafeIndex :: (Word64, Word64) -> Word64 -> Int inRange :: (Word64, Word64) -> Word64 -> Bool # rangeSize :: (Word64, Word64) -> Int # unsafeRangeSize :: (Word64, Word64) -> Int
Ix ()	Since: base-2.1
Instance details Defined in GHC.Arr Methods range :: ((), ()) -> [()] # index :: ((), ()) -> () -> Int # unsafeIndex :: ((), ()) -> () -> Int inRange :: ((), ()) -> () -> Bool # rangeSize :: ((), ()) -> Int # unsafeRangeSize :: ((), ()) -> Int
Ix SeekMode	Since: base-4.2.0.0
Instance details Defined in GHC.IO.Device Methods range :: (SeekMode, SeekMode) -> [SeekMode] # index :: (SeekMode, SeekMode) -> SeekMode -> Int # unsafeIndex :: (SeekMode, SeekMode) -> SeekMode -> Int inRange :: (SeekMode, SeekMode) -> SeekMode -> Bool # rangeSize :: (SeekMode, SeekMode) -> Int # unsafeRangeSize :: (SeekMode, SeekMode) -> Int
Ix Associativity	Since: base-4.9.0.0
Instance details Defined in GHC.Generics Methods range :: (Associativity, Associativity) -> [Associativity] # index :: (Associativity, Associativity) -> Associativity -> Int # unsafeIndex :: (Associativity, Associativity) -> Associativity -> Int inRange :: (Associativity, Associativity) -> Associativity -> Bool # rangeSize :: (Associativity, Associativity) -> Int # unsafeRangeSize :: (Associativity, Associativity) -> Int
Ix SourceUnpackedness	Since: base-4.9.0.0
Instance details Defined in GHC.Generics Methods range :: (SourceUnpackedness, SourceUnpackedness) -> [SourceUnpackedness] # index :: (SourceUnpackedness, SourceUnpackedness) -> SourceUnpackedness -> Int # unsafeIndex :: (SourceUnpackedness, SourceUnpackedness) -> SourceUnpackedness -> Int inRange :: (SourceUnpackedness, SourceUnpackedness) -> SourceUnpackedness -> Bool # rangeSize :: (SourceUnpackedness, SourceUnpackedness) -> Int # unsafeRangeSize :: (SourceUnpackedness, SourceUnpackedness) -> Int
Ix SourceStrictness	Since: base-4.9.0.0
Instance details Defined in GHC.Generics Methods range :: (SourceStrictness, SourceStrictness) -> [SourceStrictness] # index :: (SourceStrictness, SourceStrictness) -> SourceStrictness -> Int # unsafeIndex :: (SourceStrictness, SourceStrictness) -> SourceStrictness -> Int inRange :: (SourceStrictness, SourceStrictness) -> SourceStrictness -> Bool # rangeSize :: (SourceStrictness, SourceStrictness) -> Int # unsafeRangeSize :: (SourceStrictness, SourceStrictness) -> Int
Ix DecidedStrictness	Since: base-4.9.0.0
Instance details Defined in GHC.Generics Methods range :: (DecidedStrictness, DecidedStrictness) -> [DecidedStrictness] # index :: (DecidedStrictness, DecidedStrictness) -> DecidedStrictness -> Int # unsafeIndex :: (DecidedStrictness, DecidedStrictness) -> DecidedStrictness -> Int inRange :: (DecidedStrictness, DecidedStrictness) -> DecidedStrictness -> Bool # rangeSize :: (DecidedStrictness, DecidedStrictness) -> Int # unsafeRangeSize :: (DecidedStrictness, DecidedStrictness) -> Int
Ix IOMode	Since: base-4.2.0.0
Instance details Defined in GHC.IO.IOMode Methods range :: (IOMode, IOMode) -> [IOMode] # index :: (IOMode, IOMode) -> IOMode -> Int # unsafeIndex :: (IOMode, IOMode) -> IOMode -> Int inRange :: (IOMode, IOMode) -> IOMode -> Bool # rangeSize :: (IOMode, IOMode) -> Int # unsafeRangeSize :: (IOMode, IOMode) -> Int
Ix GeneralCategory	Since: base-2.1
Instance details Defined in GHC.Unicode Methods range :: (GeneralCategory, GeneralCategory) -> [GeneralCategory] # index :: (GeneralCategory, GeneralCategory) -> GeneralCategory -> Int # unsafeIndex :: (GeneralCategory, GeneralCategory) -> GeneralCategory -> Int inRange :: (GeneralCategory, GeneralCategory) -> GeneralCategory -> Bool # rangeSize :: (GeneralCategory, GeneralCategory) -> Int # unsafeRangeSize :: (GeneralCategory, GeneralCategory) -> Int
(Ix a, Ix b) => Ix (a, b)	Since: base-2.1
Instance details Defined in GHC.Arr Methods range :: ((a, b), (a, b)) -> [(a, b)] # index :: ((a, b), (a, b)) -> (a, b) -> Int # unsafeIndex :: ((a, b), (a, b)) -> (a, b) -> Int inRange :: ((a, b), (a, b)) -> (a, b) -> Bool # rangeSize :: ((a, b), (a, b)) -> Int # unsafeRangeSize :: ((a, b), (a, b)) -> Int
(Ix a1, Ix a2, Ix a3) => Ix (a1, a2, a3)	Since: base-2.1
Instance details Defined in GHC.Arr Methods range :: ((a1, a2, a3), (a1, a2, a3)) -> [(a1, a2, a3)] # index :: ((a1, a2, a3), (a1, a2, a3)) -> (a1, a2, a3) -> Int # unsafeIndex :: ((a1, a2, a3), (a1, a2, a3)) -> (a1, a2, a3) -> Int inRange :: ((a1, a2, a3), (a1, a2, a3)) -> (a1, a2, a3) -> Bool # rangeSize :: ((a1, a2, a3), (a1, a2, a3)) -> Int # unsafeRangeSize :: ((a1, a2, a3), (a1, a2, a3)) -> Int
Ix a => Ix (Const a b)	Since: base-4.9.0.0
Instance details Defined in Data.Functor.Const Methods range :: (Const a b, Const a b) -> [Const a b] # index :: (Const a b, Const a b) -> Const a b -> Int # unsafeIndex :: (Const a b, Const a b) -> Const a b -> Int inRange :: (Const a b, Const a b) -> Const a b -> Bool # rangeSize :: (Const a b, Const a b) -> Int # unsafeRangeSize :: (Const a b, Const a b) -> Int
(Ix a1, Ix a2, Ix a3, Ix a4) => Ix (a1, a2, a3, a4)	Since: base-2.1
Instance details Defined in GHC.Arr Methods range :: ((a1, a2, a3, a4), (a1, a2, a3, a4)) -> [(a1, a2, a3, a4)] # index :: ((a1, a2, a3, a4), (a1, a2, a3, a4)) -> (a1, a2, a3, a4) -> Int # unsafeIndex :: ((a1, a2, a3, a4), (a1, a2, a3, a4)) -> (a1, a2, a3, a4) -> Int inRange :: ((a1, a2, a3, a4), (a1, a2, a3, a4)) -> (a1, a2, a3, a4) -> Bool # rangeSize :: ((a1, a2, a3, a4), (a1, a2, a3, a4)) -> Int # unsafeRangeSize :: ((a1, a2, a3, a4), (a1, a2, a3, a4)) -> Int
(Ix a1, Ix a2, Ix a3, Ix a4, Ix a5) => Ix (a1, a2, a3, a4, a5)	Since: base-2.1
Instance details Defined in GHC.Arr Methods range :: ((a1, a2, a3, a4, a5), (a1, a2, a3, a4, a5)) -> [(a1, a2, a3, a4, a5)] # index :: ((a1, a2, a3, a4, a5), (a1, a2, a3, a4, a5)) -> (a1, a2, a3, a4, a5) -> Int # unsafeIndex :: ((a1, a2, a3, a4, a5), (a1, a2, a3, a4, a5)) -> (a1, a2, a3, a4, a5) -> Int inRange :: ((a1, a2, a3, a4, a5), (a1, a2, a3, a4, a5)) -> (a1, a2, a3, a4, a5) -> Bool # rangeSize :: ((a1, a2, a3, a4, a5), (a1, a2, a3, a4, a5)) -> Int # unsafeRangeSize :: ((a1, a2, a3, a4, a5), (a1, a2, a3, a4, a5)) -> Int

Deriving Instances of `Ix`

It is possible to derive an instance of Ix automatically, using a deriving clause on a data declaration. Such derived instance declarations for the class Ix are only possible for enumerations (i.e. datatypes having only nullary constructors) and single-constructor datatypes, whose constituent types are instances of Ix. A Haskell implementation must provide Ix instances for tuples up to at least size 15.

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:

instance  (Ix a, Ix b)  => Ix (a,b) where
        range ((l,l'),(u,u'))
                = [(i,i') | i <- range (l,u), i' <- range (l',u')]
        index ((l,l'),(u,u')) (i,i')
                =  index (l,u) i * rangeSize (l',u') + index (l',u') i'
        inRange ((l,l'),(u,u')) (i,i')
                = inRange (l,u) i && inRange (l',u') i'

-- Instances for other tuples are obtained from this scheme:
--
--  instance  (Ix a1, Ix a2, ... , Ix ak) => Ix (a1,a2,...,ak)  where
--      range ((l1,l2,...,lk),(u1,u2,...,uk)) =
--          [(i1,i2,...,ik) | i1 <- range (l1,u1),
--                            i2 <- range (l2,u2),
--                            ...
--                            ik <- range (lk,uk)]
--
--      index ((l1,l2,...,lk),(u1,u2,...,uk)) (i1,i2,...,ik) =
--        index (lk,uk) ik + rangeSize (lk,uk) * (
--         index (lk-1,uk-1) ik-1 + rangeSize (lk-1,uk-1) * (
--          ...
--           index (l1,u1)))
--
--      inRange ((l1,l2,...lk),(u1,u2,...,uk)) (i1,i2,...,ik) =
--          inRange (l1,u1) i1 && inRange (l2,u2) i2 &&
--              ... && inRange (lk,uk) ik

The Ix class

Deriving Instances of Ix

The `Ix` class

Deriving Instances of `Ix`