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Add MaybeK wrapper for RxJava Maybe #862
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ad2b3a1
add MaybeK
JorgeCastilloPrz ad2a368
add MaybeK instances
JorgeCastilloPrz 5073d43
add MaybeK tests including law tests
JorgeCastilloPrz 7106999
add foldable instance
JorgeCastilloPrz d319d8d
redefine foldLeft and foldRight in terms of fold
JorgeCastilloPrz ed92f6f
add docs
JorgeCastilloPrz 524bb57
refactor fold to expression
JorgeCastilloPrz e1b3544
Merge branch 'master' into add-wrapper-for-rxjava-maybe
pakoito cf96dc4
fix fold when empty and add tests
JorgeCastilloPrz 5ebf7ea
Merge branch 'add-wrapper-for-rxjava-maybe' of github.com:arrow-kt/ar…
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83 changes: 83 additions & 0 deletions
83
modules/effects/arrow-effects-rx2/src/main/kotlin/arrow/effects/MaybeK.kt
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,83 @@ | ||
| package arrow.effects | ||
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| import arrow.core.* | ||
| import arrow.effects.typeclasses.Proc | ||
| import arrow.higherkind | ||
| import io.reactivex.Maybe | ||
| import io.reactivex.MaybeEmitter | ||
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| fun <A> Maybe<A>.k(): MaybeK<A> = MaybeK(this) | ||
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| fun <A> MaybeKOf<A>.value(): Maybe<A> = this.fix().maybe | ||
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| @higherkind | ||
| data class MaybeK<A>(val maybe: Maybe<A>) : MaybeKOf<A>, MaybeKKindedJ<A> { | ||
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| fun <B> map(f: (A) -> B): MaybeK<B> = | ||
| maybe.map(f).k() | ||
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| fun <B> ap(fa: MaybeKOf<(A) -> B>): MaybeK<B> = | ||
| flatMap { a -> fa.fix().map { ff -> ff(a) } } | ||
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| fun <B> flatMap(f: (A) -> MaybeKOf<B>): MaybeK<B> = | ||
| maybe.flatMap { f(it).fix().maybe }.k() | ||
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| fun <B> fold(ifEmpty: () -> B, ifSome: (A) -> B): B = when { | ||
| maybe.isEmpty.blockingGet() -> ifEmpty() | ||
| else -> ifSome(this.maybe.blockingGet()) | ||
| } | ||
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| fun <B> foldLeft(b: B, f: (B, A) -> B): B = | ||
| fold({ b }, { a -> f(b, a) }) | ||
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| fun <B> foldRight(lb: Eval<B>, f: (A, Eval<B>) -> Eval<B>): Eval<B> = | ||
| Eval.defer { fold({ lb }, { a -> f(a, lb) }) } | ||
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| fun isEmpty(): Boolean = maybe.isEmpty.blockingGet() | ||
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| fun nonEmpty(): Boolean = !isEmpty() | ||
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| fun exists(predicate: Predicate<A>): Boolean = fold({ false }, { a -> predicate(a) }) | ||
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| fun forall(p: Predicate<A>): Boolean = fold({ true }, p) | ||
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| fun handleErrorWith(function: (Throwable) -> MaybeK<A>): MaybeK<A> = | ||
| maybe.onErrorResumeNext { t: Throwable -> function(t).maybe }.k() | ||
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| fun runAsync(cb: (Either<Throwable, A>) -> MaybeKOf<Unit>): MaybeK<Unit> = | ||
| maybe.flatMap { cb(Right(it)).value() }.onErrorResumeNext(io.reactivex.functions.Function { cb(Left(it)).value() }).k() | ||
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| companion object { | ||
| fun <A> just(a: A): MaybeK<A> = | ||
| Maybe.just(a).k() | ||
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| fun <A> raiseError(t: Throwable): MaybeK<A> = | ||
| Maybe.error<A>(t).k() | ||
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| operator fun <A> invoke(fa: () -> A): MaybeK<A> = | ||
| defer { just(fa()) } | ||
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| fun <A> defer(fa: () -> MaybeKOf<A>): MaybeK<A> = | ||
| Maybe.defer { fa().value() }.k() | ||
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| fun <A> async(fa: Proc<A>): MaybeK<A> = | ||
| Maybe.create({ emitter: MaybeEmitter<A> -> | ||
| fa { either: Either<Throwable, A> -> | ||
| either.fold({ | ||
| emitter.onError(it) | ||
| }, { | ||
| emitter.onSuccess(it) | ||
| }) | ||
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| } | ||
| }).k() | ||
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| tailrec fun <A, B> tailRecM(a: A, f: (A) -> MaybeKOf<Either<A, B>>): MaybeK<B> { | ||
| val either = f(a).fix().value().blockingGet() | ||
| return when (either) { | ||
| is Either.Left -> tailRecM(either.a, f) | ||
| is Either.Right -> Maybe.just(either.b).k() | ||
| } | ||
| } | ||
| } | ||
| } | ||
115 changes: 115 additions & 0 deletions
115
modules/effects/arrow-effects-rx2/src/main/kotlin/arrow/effects/MaybeKInstances.kt
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,115 @@ | ||
| package arrow.effects | ||
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| import arrow.Kind | ||
| import arrow.core.Either | ||
| import arrow.core.Eval | ||
| import arrow.effects.typeclasses.Async | ||
| import arrow.effects.typeclasses.Effect | ||
| import arrow.effects.typeclasses.MonadDefer | ||
| import arrow.effects.typeclasses.Proc | ||
| import arrow.instance | ||
| import arrow.typeclasses.* | ||
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| @instance(MaybeK::class) | ||
| interface MaybeKFunctorInstance : Functor<ForMaybeK> { | ||
| override fun <A, B> Kind<ForMaybeK, A>.map(f: (A) -> B): MaybeK<B> = | ||
| fix().map(f) | ||
| } | ||
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| @instance(MaybeK::class) | ||
| interface MaybeKApplicativeInstance : Applicative<ForMaybeK> { | ||
| override fun <A, B> MaybeKOf<A>.ap(ff: MaybeKOf<(A) -> B>): MaybeK<B> = | ||
| fix().ap(ff) | ||
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| override fun <A, B> Kind<ForMaybeK, A>.map(f: (A) -> B): MaybeK<B> = | ||
| fix().map(f) | ||
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| override fun <A> just(a: A): MaybeK<A> = | ||
| MaybeK.just(a) | ||
| } | ||
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| @instance(MaybeK::class) | ||
| interface MaybeKMonadInstance : Monad<ForMaybeK> { | ||
| override fun <A, B> MaybeKOf<A>.ap(ff: MaybeKOf<(A) -> B>): MaybeK<B> = | ||
| fix().ap(ff) | ||
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| override fun <A, B> MaybeKOf<A>.flatMap(f: (A) -> Kind<ForMaybeK, B>): MaybeK<B> = | ||
| fix().flatMap(f) | ||
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| override fun <A, B> MaybeKOf<A>.map(f: (A) -> B): MaybeK<B> = | ||
| fix().map(f) | ||
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| override fun <A, B> tailRecM(a: A, f: kotlin.Function1<A, MaybeKOf<arrow.core.Either<A, B>>>): MaybeK<B> = | ||
| MaybeK.tailRecM(a, f) | ||
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| override fun <A> just(a: A): MaybeK<A> = | ||
| MaybeK.just(a) | ||
| } | ||
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| @instance(MaybeK::class) | ||
| interface MaybeKFoldableInstance : Foldable<ForMaybeK> { | ||
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| override fun <A, B> Kind<ForMaybeK, A>.foldLeft(b: B, f: (B, A) -> B): B = | ||
| fix().foldLeft(b, f) | ||
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| override fun <A, B> Kind<ForMaybeK, A>.foldRight(lb: Eval<B>, f: (A, Eval<B>) -> Eval<B>): Eval<B> = | ||
| fix().foldRight(lb, f) | ||
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| override fun <A> Kind<ForMaybeK, A>.isEmpty(): Boolean = | ||
| fix().isEmpty() | ||
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| override fun <A> Kind<ForMaybeK, A>.exists(p: (A) -> Boolean): Boolean = | ||
| fix().exists(p) | ||
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| override fun <A> MaybeKOf<A>.forAll(p: (A) -> Boolean): Boolean = | ||
| fix().forall(p) | ||
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| override fun <A> Kind<ForMaybeK, A>.nonEmpty(): Boolean = | ||
| fix().nonEmpty() | ||
| } | ||
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| @instance(MaybeK::class) | ||
| interface MaybeKApplicativeErrorInstance : | ||
| MaybeKApplicativeInstance, | ||
| ApplicativeError<ForMaybeK, Throwable> { | ||
| override fun <A> raiseError(e: Throwable): MaybeK<A> = | ||
| MaybeK.raiseError(e) | ||
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| override fun <A> MaybeKOf<A>.handleErrorWith(f: (Throwable) -> MaybeKOf<A>): MaybeK<A> = | ||
| fix().handleErrorWith { f(it).fix() } | ||
| } | ||
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| @instance(MaybeK::class) | ||
| interface MaybeKMonadErrorInstance : | ||
| MaybeKMonadInstance, | ||
| MonadError<ForMaybeK, Throwable> { | ||
| override fun <A> raiseError(e: Throwable): MaybeK<A> = | ||
| MaybeK.raiseError(e) | ||
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| override fun <A> MaybeKOf<A>.handleErrorWith(f: (Throwable) -> MaybeKOf<A>): MaybeK<A> = | ||
| fix().handleErrorWith { f(it).fix() } | ||
| } | ||
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| @instance(MaybeK::class) | ||
| interface MaybeKMonadDeferInstance : | ||
| MaybeKMonadErrorInstance, | ||
| MonadDefer<ForMaybeK> { | ||
| override fun <A> defer(fa: () -> MaybeKOf<A>): MaybeK<A> = | ||
| MaybeK.defer(fa) | ||
| } | ||
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| @instance(MaybeK::class) | ||
| interface MaybeKAsyncInstance : | ||
| MaybeKMonadDeferInstance, | ||
| Async<ForMaybeK> { | ||
| override fun <A> async(fa: Proc<A>): MaybeK<A> = | ||
| MaybeK.async(fa) | ||
| } | ||
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| @instance(MaybeK::class) | ||
| interface MaybeKEffectInstance : | ||
| MaybeKAsyncInstance, | ||
| Effect<ForMaybeK> { | ||
| override fun <A> MaybeKOf<A>.runAsync(cb: (Either<Throwable, A>) -> MaybeKOf<Unit>): MaybeK<Unit> = | ||
| fix().runAsync(cb) | ||
| } |
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According to RxJava's docs,
this.maybe.blockingGet()returnsnullfor no value andAfor a value. Given that RxJava2 doesn't allow nulls inMaybe, you can rewrite this to be simpler:There was a problem hiding this comment.
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I would suggest adding a new test for it too.
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I'll address both comments tomorrow. Out of home today, Champions League finals tonight 💥
If you're hurry for a release, feel free to push those changes. Otherwise I'll do.