base-4.0.0.0: Basic librariesSource codeContentsIndex
Data.Ord
Portabilityportable
Stabilitystable
Maintainerlibraries@haskell.org
Description
Orderings
Synopsis
class Eq a => Ord a where
compare :: a -> a -> Ordering
(<) :: a -> a -> Bool
(>=) :: a -> a -> Bool
(>) :: a -> a -> Bool
(<=) :: a -> a -> Bool
max :: a -> a -> a
min :: a -> a -> a
comparing :: Ord a => (b -> a) -> b -> b -> Ordering
Documentation
class Eq a => Ord a whereSource

The Ord class is used for totally ordered datatypes.

Instances of Ord can be derived for any user-defined datatype whose constituent types are in Ord. The declared order of the constructors in the data declaration determines the ordering in derived Ord instances. The Ordering datatype allows a single comparison to determine the precise ordering of two objects.

Minimal complete definition: either compare or <=. Using compare can be more efficient for complex types.

Methods
compare :: a -> a -> OrderingSource
(<) :: a -> a -> BoolSource
(>=) :: a -> a -> BoolSource
(>) :: a -> a -> BoolSource
(<=) :: a -> a -> BoolSource
max :: a -> a -> aSource
min :: a -> a -> aSource
show/hide Instances
Ord Bool
Ord Char
Ord Double
Ord Float
Ord Int
Ord Int8
Ord Int16
Ord Int32
Ord Int64
Ord Integer
Ord Ordering
Ord Word
Ord Word8
Ord Word16
Ord Word32
Ord Word64
Ord ()
Ord ArithException
Ord CUIntPtr
Ord CIntMax
Ord CChar
Ord CSChar
Ord CUChar
Ord CShort
Ord CUShort
Ord CInt
Ord CUInt
Ord CLong
Ord CULong
Ord CLLong
Ord CULLong
Ord CFloat
Ord CDouble
Ord CLDouble
Ord CPtrdiff
Ord CSize
Ord CWchar
Ord CSigAtomic
Ord CClock
Ord CTime
Ord CIntPtr
Ord CUIntMax
Ord BufferMode
Ord ArrayException
Ord ExitCode
Ord IOMode
Ord AsyncException
Ord GeneralCategory
Ord WordPtr
Ord IntPtr
Ord CPid
Ord CSsize
Ord CDev
Ord CIno
Ord CMode
Ord COff
Ord Fd
Ord ThreadId
Ord BlockReason
Ord ThreadStatus
Ord ConsoleEvent
Ord SeekMode
Ord All
Ord Any
Ord Unique
Ord Version
Ord a => Ord ([] a)
Integral a => Ord (Ratio a)
Ord (Ptr a)
Ord (FunPtr a)
Ord a => Ord ([::] a)
Ord a => Ord (Maybe a)
Ord (ForeignPtr a)
Ord a => Ord (Down a)
Ord (Fixed a)
Ord a => Ord (Dual a)
Ord a => Ord (Sum a)
Ord a => Ord (Product a)
Ord a => Ord (First a)
Ord a => Ord (Last a)
(Ord a, Ord b) => Ord (Either a b)
(Ord a, Ord b) => Ord ((,) a b)
(Ix i, Ord e) => Ord (Array i e)
(Ord a, Ord b, Ord c) => Ord ((,,) a b c)
(Ord a, Ord b, Ord c, Ord d) => Ord ((,,,) a b c d)
(Ord a, Ord b, Ord c, Ord d, Ord e) => Ord ((,,,,) a b c d e)
(Ord a, Ord b, Ord c, Ord d, Ord e, Ord f) => Ord ((,,,,,) a b c d e f)
(Ord a, Ord b, Ord c, Ord d, Ord e, Ord f, Ord g) => Ord ((,,,,,,) a b c d e f g)
(Ord a, Ord b, Ord c, Ord d, Ord e, Ord f, Ord g, Ord h) => Ord ((,,,,,,,) a b c d e f g h)
(Ord a, Ord b, Ord c, Ord d, Ord e, Ord f, Ord g, Ord h, Ord i) => Ord ((,,,,,,,,) a b c d e f g h i)
(Ord a, Ord b, Ord c, Ord d, Ord e, Ord f, Ord g, Ord h, Ord i, Ord j) => Ord ((,,,,,,,,,) a b c d e f g h i j)
(Ord a, Ord b, Ord c, Ord d, Ord e, Ord f, Ord g, Ord h, Ord i, Ord j, Ord k) => Ord ((,,,,,,,,,,) a b c d e f g h i j k)
(Ord a, Ord b, Ord c, Ord d, Ord e, Ord f, Ord g, Ord h, Ord i, Ord j, Ord k, Ord l) => Ord ((,,,,,,,,,,,) a b c d e f g h i j k l)
(Ord a, Ord b, Ord c, Ord d, Ord e, Ord f, Ord g, Ord h, Ord i, Ord j, Ord k, Ord l, Ord m) => Ord ((,,,,,,,,,,,,) a b c d e f g h i j k l m)
(Ord a, Ord b, Ord c, Ord d, Ord e, Ord f, Ord g, Ord h, Ord i, Ord j, Ord k, Ord l, Ord m, Ord n) => Ord ((,,,,,,,,,,,,,) a b c d e f g h i j k l m n)
(Ord a, Ord b, Ord c, Ord d, Ord e, Ord f, Ord g, Ord h, Ord i, Ord j, Ord k, Ord l, Ord m, Ord n, Ord o) => Ord ((,,,,,,,,,,,,,,) a b c d e f g h i j k l m n o)
comparing :: Ord a => (b -> a) -> b -> b -> OrderingSource
 comparing p x y = compare (p x) (p y)

Useful combinator for use in conjunction with the xxxBy family of functions from Data.List, for example: 

   ... sortBy (comparing fst) ...
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