base-4.7.0.0: Basic libraries

Copyright | (c) The University of Glasgow 2005
License | BSD-style (see the file libraries/base/LICENSE)
Maintainer | libraries@haskell.org
Stability | stable
Portability | portable
Safe Haskell | Trustworthy
Language | Haskell2010

Data.Ord

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
- data Ordering :: *
  - = LT
  - | EQ
  - | GT
- newtype Down a = Down a
- comparing :: Ord a => (b -> a) -> b -> b -> Ordering

# Documentation

class Eq a => Ord a where Source

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.

Minimal complete definition

compare | (<=)

Methods

compare :: a -> a -> Ordering Source

(<) :: a -> a -> Bool infix 4 Source

(>=) :: a -> a -> Bool infix 4 Source

(>) :: a -> a -> Bool infix 4 Source

(<=) :: a -> a -> Bool infix 4 Source

max :: a -> a -> a Source

min :: a -> a -> a Source

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 Fingerprint |
Ord TyCon |
Ord TypeRep |
Ord Associativity |
Ord Fixity |
Ord Arity |
Ord Any |
Ord All |
Ord ArithException |
Ord ErrorCall |
Ord CUIntMax |
Ord CIntMax |
Ord CUIntPtr |
Ord CIntPtr |
Ord CSUSeconds |
Ord CUSeconds |
Ord CTime |
Ord CClock |
Ord CSigAtomic |
Ord CWchar |
Ord CSize |
Ord CPtrdiff |
Ord CDouble |
Ord CFloat |
Ord CULLong |
Ord CLLong |
Ord CULong |
Ord CLong |
Ord CUInt |
Ord CInt |
Ord CUShort |
Ord CShort |
Ord CUChar |
Ord CSChar |
Ord CChar |
Ord GeneralCategory |
Ord IntPtr |
Ord WordPtr |
Ord SeekMode |
Ord NewlineMode |
Ord Newline |
Ord BufferMode |
Ord ExitCode |
Ord ArrayException |
Ord AsyncException |
Ord Fd |
Ord CRLim |
Ord CTcflag |
Ord CSpeed |
Ord CCc |
Ord CUid |
Ord CNlink |
Ord CGid |
Ord CSsize |
Ord CPid |
Ord COff |
Ord CMode |
Ord CIno |
Ord CDev |
Ord ThreadStatus |
Ord BlockReason |
Ord ThreadId |
Ord IOMode |
Ord TyCon |
Ord TypeRep |
Ord TypeRepKey |
Ord SomeSymbol |
Ord SomeNat |
Ord Version |
Ord Unique |
Ord a => Ord [a] |
Integral a => Ord (Ratio a) |
Ord (Ptr a) |
Ord (FunPtr a) |
Ord (U1 p) |
Ord p => Ord (Par1 p) |
Ord a => Ord (Maybe a) |
Ord a => Ord (Down a) |
Ord a => Ord (Last a) |
Ord a => Ord (First a) |
Ord a => Ord (Product a) |
Ord a => Ord (Sum a) |
Ord a => Ord (Dual a) |
Ord (ForeignPtr a) |
Ord a => Ord (ZipList a) |
Ord (Fixed a) |
(Ord a, Ord b) => Ord (Either a b) |
Ord (f p) => Ord (Rec1 f p) |
(Ord a, Ord b) => Ord (a, b) |
Ord (Proxy k s) |
Ord c => Ord (K1 i c p) |
(Ord (f p), Ord (g p)) => Ord ((:+:) f g p) |
(Ord (f p), Ord (g p)) => Ord ((:*:) f g p) |
Ord (f (g p)) => Ord ((:.:) f g p) |
(Ord a, Ord b, Ord c) => Ord (a, b, c) |
Ord ((:~:) k a b) |
Ord (Coercion k a b) |
Ord (f p) => Ord (M1 i c f p) |
(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) |

data Ordering :: * Source

Constructors

LT |
EQ |
GT |

Instances

Bounded Ordering |
Enum Ordering |
Eq Ordering |
Data Ordering |
Ord Ordering |
Read Ordering |
Show Ordering |
Ix Ordering |
Generic Ordering |
Typeable Ordering |
Monoid Ordering |
Typeable * Ordering |
type Rep Ordering |
type (==) Ordering a b |

newtype Down a

The `Down` type allows you to reverse sort order conveniently. A value of type ``Down` a` contains a value of type `a` (represented as ``Down` a`). If `a` has an ``Ord`` instance associated with it then comparing two values thus wrapped will give you the opposite of their normal sort order. This is particularly useful when sorting in generalised list comprehensions, as in: `then sortWith by `Down` x`

Provides `Show` and `Read` instances (since: 4.7.0.0).

Since: 4.6.0.0

Constructors

Down a |

Instances

Eq a => Eq (Down a) |
Ord a => Ord (Down a) |
Read a => Read (Down a) |
Show a => Show (Down a) |

comparing :: Ord a => (b -> a) -> b -> b -> Ordering

    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) ...