[Arrow 2.0] Effect without suspending shift #2797
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,104 @@ | ||
| @file:JvmMultifileClass | ||
| @file:JvmName("Effect") | ||
| @file:OptIn(ExperimentalTypeInference::class, ExperimentalContracts::class) | ||
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| package arrow.core.continuations | ||
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| import arrow.core.Either | ||
| import arrow.core.EmptyValue | ||
| import arrow.core.Ior | ||
| import arrow.core.None | ||
| import arrow.core.Option | ||
| import arrow.core.Some | ||
| import arrow.core.identity | ||
| import arrow.typeclasses.Semigroup | ||
| import kotlin.contracts.ExperimentalContracts | ||
| import kotlin.contracts.contract | ||
| import kotlin.experimental.ExperimentalTypeInference | ||
| import kotlin.jvm.JvmInline | ||
| import kotlin.jvm.JvmMultifileClass | ||
| import kotlin.jvm.JvmName | ||
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| public inline fun <E, A> either(@BuilderInference block: Shift<E>.() -> A): Either<E, A> = | ||
| fold({ block.invoke(this) }, { Either.Left(it) }, { Either.Right(it) }) | ||
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| public inline fun <A> nullable(block: NullableShift.() -> A): A? = | ||
| fold({ block(NullableShift(this)) }, { null }, ::identity) | ||
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| public inline fun <A> result(action: ResultShift.() -> A): Result<A> = | ||
| fold({ action(ResultShift(this)) }, Result.Companion::failure, Result.Companion::success) | ||
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| public inline fun <A> option(action: OptionShift.() -> A): Option<A> = | ||
| fold({ action(OptionShift(this)) }, ::identity, ::Some) | ||
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| public inline fun <E, A> ior(semigroup: Semigroup<E>, @BuilderInference action: IorShift<E>.() -> A): Ior<E, A> = | ||
| fold({ IorShift(semigroup, this).invoke(action) }, { Ior.Left(it) }, ::identity) | ||
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| @JvmInline | ||
| public value class NullableShift(private val cont: Shift<Nothing?>) : Shift<Nothing?> { | ||
| @EffectDSL | ||
| public fun ensure(value: Boolean): Unit = ensure(value) { null } | ||
| override fun <B> shift(r: Nothing?): B = cont.shift(r) | ||
| public fun <B> Option<B>.bind(): B = bind { shift(null) } | ||
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| public fun <B> B?.bind(): B { | ||
| contract { returns() implies (this@bind != null) } | ||
| return this ?: shift(null) | ||
| } | ||
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| public fun <B> ensureNotNull(value: B?): B { | ||
| contract { returns() implies (value != null) } | ||
| return ensureNotNull(value) { null } | ||
| } | ||
| } | ||
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| @JvmInline | ||
| public value class ResultShift(private val cont: Shift<Throwable>) : Shift<Throwable> { | ||
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| override fun <B> shift(r: Throwable): B = cont.shift(r) | ||
| public fun <B> Result<B>.bind(): B = fold(::identity) { shift(it) } | ||
| } | ||
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| @JvmInline | ||
| public value class OptionShift(private val cont: Shift<None>) : Shift<None> { | ||
| override fun <B> shift(r: None): B = cont.shift(r) | ||
| public fun <B> Option<B>.bind(): B = bind { shift(None) } | ||
| public fun ensure(value: Boolean): Unit = ensure(value) { None } | ||
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| public fun <B> ensureNotNull(value: B?): B { | ||
| contract { returns() implies (value != null) } | ||
| return ensureNotNull(value) { None } | ||
| } | ||
| } | ||
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| public class IorShift<E> @PublishedApi internal constructor(semigroup: Semigroup<E>, private val effect: Shift<E>) : | ||
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There was a problem hiding this comment. These may be an exception to what I said above, but it's also not a value class since it takes more than one arg. There was a problem hiding this comment. Sam issue, it can be implemented for There was a problem hiding this comment. Can you send in a gist link, please? 😄 |
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| Shift<E>, Semigroup<E> by semigroup { | ||
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| // TODO this is a mess... | ||
| @PublishedApi | ||
| internal var leftState: AtomicRef<Any?> = AtomicRef(EmptyValue) | ||
| override fun <B> shift(r: E): B = effect.shift(combine(r)) | ||
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| public fun <B> Ior<E, B>.bind(): B = | ||
| when (this) { | ||
| is Ior.Left -> shift(value) | ||
| is Ior.Right -> value | ||
| is Ior.Both -> { | ||
| combine(leftValue) | ||
| rightValue | ||
| } | ||
| } | ||
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| @PublishedApi | ||
| internal inline operator fun <A> invoke(action: IorShift<E>.() -> A): Ior<E, A> { | ||
| val res = action(this) | ||
| val leftState = leftState.get() | ||
| return if (leftState === EmptyValue) Ior.Right(res) | ||
| else Ior.Both(EmptyValue.unbox(leftState), res) | ||
| } | ||
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| @Suppress("UNCHECKED_CAST") | ||
| private fun combine(other: E): E = | ||
| leftState.updateAndGet { state -> | ||
| if (state === EmptyValue) other else EmptyValue.unbox<E>(state).combine(other) | ||
| } as E | ||
| } | ||
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These impls are so much nicer and simpler now 👏