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

Data.Unique

Contents

Unique objects

Description

An abstract interface to a unique symbol generator.

Synopsis

Unique objects

data Unique Source #

An abstract unique object. Objects of type Unique may be compared for equality and ordering and hashed into Int .

>>> :{
do x <- newUnique
 print (x == x)
 y <- newUnique
 print (x == y)
:}
True
False

Instances

Instances details

Eq Unique Source #

Instance details

Defined in GHC.Internal.Data.Unique

Methods

(==) :: Unique -> Unique -> Bool Source #

(/=) :: Unique -> Unique -> Bool Source #

Ord Unique Source #

Instance details

Defined in GHC.Internal.Data.Unique

Methods

compare :: Unique -> Unique -> Ordering Source #

(<) :: Unique -> Unique -> Bool Source #

(<=) :: Unique -> Unique -> Bool Source #

(>) :: Unique -> Unique -> Bool Source #

(>=) :: Unique -> Unique -> Bool Source #

max :: Unique -> Unique -> Unique Source #

min :: Unique -> Unique -> Unique Source #

newUnique :: IO Unique Source #

Creates a new object of type Unique . The value returned will not compare equal to any other value of type Unique returned by previous calls to newUnique . There is no limit on the number of times newUnique may be called.

hashUnique :: Unique -> Int Source #

Hashes a Unique into an Int . Two Unique s may hash to the same value, although in practice this is unlikely. The Int returned makes a good hash key.