Safe Haskell	Safe
Language	Haskell2010

Unique

Synopsis

Documentation

data Unique #

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
Instance details Defined in Data.Unique Methods (==) :: Unique -> Unique -> Bool # (/=) :: Unique -> Unique -> Bool #
Ord Unique
Instance details Defined in Data.Unique Methods compare :: Unique -> Unique -> Ordering # (<) :: Unique -> Unique -> Bool # (<=) :: Unique -> Unique -> Bool # (>) :: Unique -> Unique -> Bool # (>=) :: Unique -> Unique -> Bool # max :: Unique -> Unique -> Unique # min :: Unique -> Unique -> Unique #
Hashable Unique
Instance details Defined in Data.Hashable.Class Methods hashWithSalt :: Int -> Unique -> Int # hash :: Unique -> Int #
NFData Unique	Since: deepseq-1.4.0.0
Instance details Defined in Control.DeepSeq Methods rnf :: Unique -> () #

newUnique :: IO Unique #

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 #

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.