Data.Optional

newtype Optional a

Optional is a newtype on the uncurried Church encoding of Maybe.

Constructors

• Optional (forall r. Fn2 r (a -> r) r)

Instances

• Functor Optional
• Apply Optional
• Applicative Optional
• Alt Optional
• Plus Optional
• Alternative Optional
• Bind Optional
• Monad Optional
• MonadZero Optional
• Extend Optional
• Invariant Optional
• (Semigroup a) => Semigroup (Optional a)
• (Semigroup a) => Monoid (Optional a)
• (Eq a) => Eq (Optional a)
• Eq1 Optional
• (Ord a) => Ord (Optional a)
• Ord1 Optional
• (Bounded a) => Bounded (Optional a)
• (Bounded a, Enum a) => Enum (Optional a)
• (Show a) => Show (Optional a)
• Generic (Optional a) (Sum (Constructor "Default" NoArguments) (Constructor "Use" (Argument a)))
• (Encode a) => Encode (Optional a)
• (Decode a) => Decode (Optional a)
• Foldable Optional
• Traversable Optional

default :: forall a. Optional a

Optional a default constructor. Analogous to Nothing.

use :: forall a. a -> Optional a

Optional a use constructor. Analogous to Just.

optional' :: forall r a. Optional a -> Fn2 r (a -> r) r

Optional a destructor.

optional :: forall r a. r -> (a -> r) -> Optional a -> r

A variant Optional a destructor analogous to maybe.

fromMaybe :: forall a. Maybe a -> Optional a

Convert Maybe a to Optional a.

toMaybe :: forall a. Optional a -> Maybe a

Convert Optional a to Maybe a.