Data.Lazy

data Lazy :: Type -> Type

Lazy a represents lazily-computed values of type a.

A lazy value is computed at most once - the result is saved after the first computation, and subsequent attempts to read the value simply return the saved value.

Lazy values can be created with defer, or by using the provided type class instances.

Lazy values can be evaluated by using the force function.

purerl note: Due to the nature of the BEAM platform Lazy values are not in fact lazy with the Erlang backend, but simple thunks, i.e. will be recomputed each time they are required.

Instances

• (Semiring a) => Semiring (Lazy a)
• (Ring a) => Ring (Lazy a)
• (CommutativeRing a) => CommutativeRing (Lazy a)
• (EuclideanRing a) => EuclideanRing (Lazy a)
• (Eq a) => Eq (Lazy a)
• Eq1 Lazy
• (Ord a) => Ord (Lazy a)
• Ord1 Lazy
• (Bounded a) => Bounded (Lazy a)
• (Semigroup a) => Semigroup (Lazy a)
• (Monoid a) => Monoid (Lazy a)
• (HeytingAlgebra a) => HeytingAlgebra (Lazy a)
• (BooleanAlgebra a) => BooleanAlgebra (Lazy a)
• Functor Lazy
• FunctorWithIndex Unit Lazy
• Foldable Lazy
• FoldableWithIndex Unit Lazy
• Foldable1 Lazy
• Traversable Lazy
• TraversableWithIndex Unit Lazy
• Traversable1 Lazy
• Invariant Lazy
• Apply Lazy
• Applicative Lazy
• Bind Lazy
• Monad Lazy
• Extend Lazy
• Comonad Lazy
• (Show a) => Show (Lazy a)
• Lazy (Lazy a)

defer :: forall a. (Unit -> a) -> Lazy a

Defer a computation, creating a Lazy value.

force :: forall a. Lazy a -> a

Force evaluation of a Lazy value.