Swarm.Util.Erasable

Custom extension of Semigroup to Monoid that adds identity + annihilator elements.

Documentation

data Erasable e

Extend a semigroup to a monoid by adding an identity (ENothing) and an annihilator (EErase). That is,

• ENothing <> e = e <> ENothing = e

• EErase <> e = e <> EErase = EErase

This allows us to "erase" previous values by combining with EErase. The erasableToMaybe function turns an Erasable into a Maybe by collapsing ENothing and EErase both back into Nothing.

Constructors

ENothing

EErase

EJust e

Instances

Functor Erasable

Defined in Swarm.Util.Erasable

Methods

fmap :: (a -> b) -> Erasable a -> Erasable b

(<$) :: a -> Erasable b -> Erasable a

Semigroup e => Monoid (Erasable e)

Defined in Swarm.Util.Erasable

Methods

mempty :: Erasable e

mappend :: Erasable e -> Erasable e -> Erasable e

mconcat :: [Erasable e] -> Erasable e

Semigroup e => Semigroup (Erasable e)

Defined in Swarm.Util.Erasable

Methods

(<>) :: Erasable e -> Erasable e -> Erasable e

sconcat :: NonEmpty (Erasable e) -> Erasable e

stimes :: Integral b => b -> Erasable e -> Erasable e

Show e => Show (Erasable e)

Defined in Swarm.Util.Erasable

Methods

showsPrec :: Int -> Erasable e -> ShowS

show :: Erasable e -> String

showList :: [Erasable e] -> ShowS

Eq e => Eq (Erasable e)

Defined in Swarm.Util.Erasable

Methods

(==) :: Erasable e -> Erasable e -> Bool

(/=) :: Erasable e -> Erasable e -> Bool

Ord e => Ord (Erasable e)

Defined in Swarm.Util.Erasable

Methods

compare :: Erasable e -> Erasable e -> Ordering

(<) :: Erasable e -> Erasable e -> Bool

(<=) :: Erasable e -> Erasable e -> Bool

(>) :: Erasable e -> Erasable e -> Bool

(>=) :: Erasable e -> Erasable e -> Bool

max :: Erasable e -> Erasable e -> Erasable e

min :: Erasable e -> Erasable e -> Erasable e

erasable :: a -> a -> (e -> a) -> Erasable e -> a

Generic eliminator for Erasable values.

erasableToMaybe :: Erasable e -> Maybe e

Convert an Erasable value to Maybe, turning both ENothing and EErase into Nothing.

maybeToErasable :: Maybe e -> Erasable e

Inject a Maybe value into Erasable using ENothing and EJust.