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|
(.using
[library
[lux (.except)
[abstract
[functor (.only Functor)]
[apply (.only Apply)]
[monad (.only Monad do)]
[equivalence (.only Equivalence)]]
[control
["[0]" io]
[parser
["<[0]>" code]]
[concurrency
["[0]" atom]]]
[macro (.only with_symbols)
[syntax (.only syntax)]]
[type (.only sharing)
[primitive (.except)]]]])
(primitive .public (Lazy a)
(-> [] a)
(def: (lazy' generator)
(All (_ a) (-> (-> [] a) (Lazy a)))
(let [cache (atom.atom (sharing [a]
(-> [] a)
generator
(Maybe a)
{.#None}))]
(abstraction (function (_ _)
(case (io.run! (atom.read! cache))
{.#Some value}
value
_
(let [value (generator [])]
(exec
(io.run! (atom.compare_and_swap! _ {.#Some value} cache))
value)))))))
(def: .public (value lazy)
(All (_ a) (-> (Lazy a) a))
((representation lazy) [])))
(def: .public lazy
(syntax (_ [expression <code>.any])
(with_symbols [g!_]
(in (list (` ((~! ..lazy') (function ((~ g!_) (~ g!_)) (~ expression)))))))))
(def: .public (equivalence (open "_#[0]"))
(All (_ a) (-> (Equivalence a) (Equivalence (Lazy a))))
(implementation
(def: (= left right)
(_#= (..value left)
(..value right)))))
(def: .public functor
(Functor Lazy)
(implementation
(def: (each f fa)
(lazy (f (value fa))))))
(def: .public apply
(Apply Lazy)
(implementation
(def: functor ..functor)
(def: (on fa ff)
(lazy ((value ff) (value fa))))))
(def: .public monad
(Monad Lazy)
(implementation
(def: functor ..functor)
(def: in (|>> lazy))
(def: conjoint ..value)))
|
