Safe Haskell	None
Language	Haskell2010

Mikan.Utils.Empty

Description

An empty type with some useful instances.

Synopsis

Documentation

data Empty Source #

A type with no inhabitants.

Note that Empty and Void are NOT interchangable, as they have different NFData instances. In particular, the NFData instance for Void forces the value. This is typically not desirable, as we often want to use Empty as a proxy for an __IMPOSSIBLE__.

Instances

Instances details

NFData Empty Source #	Values of type `Empty` are not forced.
Instance details Defined in Mikan.Utils.Empty Methods rnf :: Empty -> () #
Show Empty Source #
Instance details Defined in Mikan.Utils.Empty Methods showsPrec :: Int -> Empty -> ShowS # show :: Empty -> String # showList :: [Empty] -> ShowS #
Eq Empty Source #
Instance details Defined in Mikan.Utils.Empty Methods (==) :: Empty -> Empty -> Bool # (/=) :: Empty -> Empty -> Bool #
Ord Empty Source #
Instance details Defined in Mikan.Utils.Empty Methods compare :: Empty -> Empty -> Ordering # (<) :: Empty -> Empty -> Bool # (<=) :: Empty -> Empty -> Bool # (>) :: Empty -> Empty -> Bool # (>=) :: Empty -> Empty -> Bool # max :: Empty -> Empty -> Empty # min :: Empty -> Empty -> Empty #

absurd :: Empty -> a Source #

Force an Empty.

toImpossible :: Empty -> IO Impossible Source #

toImpossible e extracts the Impossible value raised via __IMPOSSIBLE__ to create the element e of type Empty.

It proceeds by evaluating e to weak head normal form and catching the exception. We are forced to wrap things in a Maybe because of catchImpossible's type.