base-4.12.0.0: Basic libraries

Copyright(c) The University of Glasgow 2001
LicenseBSD-style (see the file libraries/base/LICENSE)
Maintainerlibraries@haskell.org
Stabilityexperimental
Portabilitynon-portable
Safe HaskellTrustworthy
LanguageHaskell2010

Data.Unique

Contents

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
Eq Unique Source # 
Instance details

Defined in Data.Unique

Ord Unique Source # 
Instance details

Defined in Data.Unique

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 Uniques may hash to the same value, although in practice this is unlikely. The Int returned makes a good hash key.