effect/src/Micro.ts

The missing standard library for TypeScript, for writing production-grade software.

/**
 * A lightweight alternative to the `Effect` data type, with a subset of the functionality.
 *
 * @since 3.4.0
 * @experimental
 */
import * as Arr from "./Array.js"
import type { Channel } from "./Channel.js"
import * as Context from "./Context.js"
import type { Effect, EffectUnify, EffectUnifyIgnore } from "./Effect.js"
import * as Effectable from "./Effectable.js"
import * as Either from "./Either.js"
import * as Equal from "./Equal.js"
import type { LazyArg } from "./Function.js"
import { constTrue, constVoid, dual, identity } from "./Function.js"
import { globalValue } from "./GlobalValue.js"
import * as Hash from "./Hash.js"
import type { TypeLambda } from "./HKT.js"
import type { Inspectable } from "./Inspectable.js"
import { format, NodeInspectSymbol, toStringUnknown } from "./Inspectable.js"
import * as InternalContext from "./internal/context.js"
import * as doNotation from "./internal/doNotation.js"
import { StructuralPrototype } from "./internal/effectable.js"
import * as Option from "./Option.js"
import type { Pipeable } from "./Pipeable.js"
import { pipeArguments } from "./Pipeable.js"
import type { Predicate, Refinement } from "./Predicate.js"
import { hasProperty, isIterable, isTagged } from "./Predicate.js"
import type { Sink } from "./Sink.js"
import type { Stream } from "./Stream.js"
import type { Concurrency, Covariant, Equals, NotFunction, Simplify } from "./Types.js"
import type * as Unify from "./Unify.js"
import { SingleShotGen, YieldWrap, yieldWrapGet } from "./Utils.js"

/**
 * @since 3.4.0
 * @experimental
 * @category type ids
 */
export const TypeId: unique symbol = Symbol.for("effect/Micro")

/**
 * @since 3.4.0
 * @experimental
 * @category type ids
 */
export type TypeId = typeof TypeId

/**
 * @since 3.4.0
 * @experimental
 * @category MicroExit
 */
export const MicroExitTypeId: unique symbol = Symbol.for(
  "effect/Micro/MicroExit"
)

/**
 * @since 3.4.0
 * @experimental
 * @category MicroExit
 */
export type MicroExitTypeId = typeof TypeId

/**
 * A lightweight alternative to the `Effect` data type, with a subset of the functionality.
 *
 * @since 3.4.0
 * @experimental
 * @category models
 */
export interface Micro<out A, out E = never, out R = never> extends Effect<A, E, R> {
  readonly [TypeId]: Micro.Variance<A, E, R>
  [Symbol.iterator](): MicroIterator<Micro<A, E, R>>
  [Unify.typeSymbol]?: unknown
  [Unify.unifySymbol]?: MicroUnify<this>
  [Unify.ignoreSymbol]?: MicroUnifyIgnore
}

/**
 * @category models
 * @since 3.4.3
 */
export interface MicroUnify<A extends { [Unify.typeSymbol]?: any }> extends EffectUnify<A> {
  Micro?: () => A[Unify.typeSymbol] extends Micro<infer A0, infer E0, infer R0> | infer _ ? Micro<A0, E0, R0> : never
}

/**
 * @category models
 * @since 3.4.3
 */
export interface MicroUnifyIgnore extends EffectUnifyIgnore {
  Effect?: true
}
/**
 * @category type lambdas
 * @since 3.4.1
 */
export interface MicroTypeLambda extends TypeLambda {
  readonly type: Micro<this["Target"], this["Out1"], this["Out2"]>
}

/**
 * @since 3.4.0
 * @experimental
 */
export declare namespace Micro {
  /**
   * @since 3.4.0
   * @experimental
   */
  export interface Variance<A, E, R> {
    _A: Covariant<A>
    _E: Covariant<E>
    _R: Covariant<R>
  }

  /**
   * @since 3.4.0
   * @experimental
   */
  export type Success<T> = T extends Micro<infer _A, infer _E, infer _R> ? _A : never

  /**
   * @since 3.4.0
   * @experimental
   */
  export type Error<T> = T extends Micro<infer _A, infer _E, infer _R> ? _E : never

  /**
   * @since 3.4.0
   * @experimental
   */
  export type Context<T> = T extends Micro<infer _A, infer _E, infer _R> ? _R : never
}

/**
 * @since 3.4.0
 * @experimental
 * @category guards
 */
export const isMicro = (u: unknown): u is Micro<any, any, any> => typeof u === "object" && u !== null && TypeId in u

/**
 * @since 3.4.0
 * @experimental
 * @category models
 */
export interface MicroIterator<T extends Micro<any, any, any>> {
  next(...args: ReadonlyArray<any>): IteratorResult<YieldWrap<T>, Micro.Success<T>>
}

// ----------------------------------------------------------------------------
// MicroCause
// ----------------------------------------------------------------------------

/**
 * @since 3.4.6
 * @experimental
 * @category MicroCause
 */
export const MicroCauseTypeId = Symbol.for("effect/Micro/MicroCause")

/**
 * @since 3.4.6
 * @experimental
 * @category MicroCause
 */
export type MicroCauseTypeId = typeof MicroCauseTypeId

/**
 * A `MicroCause` is a data type that represents the different ways a `Micro` can fail.
 *
 * **Details**
 *
 * `MicroCause` comes in three forms:
 *
 * - `Die`: Indicates an unforeseen defect that wasn't planned for in the system's logic.
 * - `Fail`: Covers anticipated errors that are recognized and typically handled within the application.
 * - `Interrupt`: Signifies an operation that has been purposefully stopped.
 *
 * @since 3.4.6
 * @experimental
 * @category MicroCause
 */
export type MicroCause<E> =
  | MicroCause.Die
  | MicroCause.Fail<E>
  | MicroCause.Interrupt

/**
 * @since 3.6.6
 * @experimental
 * @category guards
 */
export const isMicroCause = (self: unknown): self is MicroCause<unknown> => hasProperty(self, MicroCauseTypeId)

/**
 * @since 3.4.6
 * @experimental
 * @category MicroCause
 */
export declare namespace MicroCause {
  /**
   * @since 3.4.6
   * @experimental
   */
  export type Error<T> = T extends MicroCause.Fail<infer E> ? E : never

  /**
   * @since 3.4.0
   * @experimental
   */
  export interface Proto<Tag extends string, E> extends Pipeable, globalThis.Error {
    readonly [MicroCauseTypeId]: {
      _E: Covariant<E>
    }
    readonly _tag: Tag
    readonly traces: ReadonlyArray<string>
  }

  /**
   * @since 3.4.6
   * @experimental
   * @category MicroCause
   */
  export interface Die extends Proto<"Die", never> {
    readonly defect: unknown
  }

  /**
   * @since 3.4.6
   * @experimental
   * @category MicroCause
   */
  export interface Fail<E> extends Proto<"Fail", E> {
    readonly error: E
  }

  /**
   * @since 3.4.6
   * @experimental
   * @category MicroCause
   */
  export interface Interrupt extends Proto<"Interrupt", never> {}
}

const microCauseVariance = {
  _E: identity
}

abstract class MicroCauseImpl<Tag extends string, E> extends globalThis.Error implements MicroCause.Proto<Tag, E> {
  readonly [MicroCauseTypeId]: {
    _E: Covariant<E>
  }
  constructor(
    readonly _tag: Tag,
    originalError: unknown,
    readonly traces: ReadonlyArray<string>
  ) {
    const causeName = `MicroCause.${_tag}`
    let name: string
    let message: string
    let stack: string
    if (originalError instanceof globalThis.Error) {
      name = `(${causeName}) ${originalError.name}`
      message = originalError.message as string
      const messageLines = message.split("\n").length
      stack = originalError.stack
        ? `(${causeName}) ${
          originalError.stack
            .split("\n")
            .slice(0, messageLines + 3)
            .join("\n")
        }`
        : `${name}: ${message}`
    } else {
      name = causeName
      message = toStringUnknown(originalError, 0)
      stack = `${name}: ${message}`
    }
    if (traces.length > 0) {
      stack += `\n    ${traces.join("\n    ")}`
    }
    super(message)
    this[MicroCauseTypeId] = microCauseVariance
    this.name = name
    this.stack = stack
  }
  pipe() {
    return pipeArguments(this, arguments)
  }
  toString() {
    return this.stack
  }
  [NodeInspectSymbol]() {
    return this.stack
  }
}

class Fail<E> extends MicroCauseImpl<"Fail", E> implements MicroCause.Fail<E> {
  constructor(
    readonly error: E,
    traces: ReadonlyArray<string> = []
  ) {
    super("Fail", error, traces)
  }
}

/**
 * @since 3.4.6
 * @experimental
 * @category MicroCause
 */
export const causeFail = <E>(
  error: E,
  traces: ReadonlyArray<string> = []
): MicroCause<E> => new Fail(error, traces)

class Die extends MicroCauseImpl<"Die", never> implements MicroCause.Die {
  constructor(
    readonly defect: unknown,
    traces: ReadonlyArray<string> = []
  ) {
    super("Die", defect, traces)
  }
}

/**
 * @since 3.4.6
 * @experimental
 * @category MicroCause
 */
export const causeDie = (
  defect: unknown,
  traces: ReadonlyArray<string> = []
): MicroCause<never> => new Die(defect, traces)

class Interrupt extends MicroCauseImpl<"Interrupt", never> implements MicroCause.Interrupt {
  constructor(traces: ReadonlyArray<string> = []) {
    super("Interrupt", "interrupted", traces)
  }
}

/**
 * @since 3.4.6
 * @experimental
 * @category MicroCause
 */
export const causeInterrupt = (
  traces: ReadonlyArray<string> = []
): MicroCause<never> => new Interrupt(traces)

/**
 * @since 3.4.6
 * @experimental
 * @category MicroCause
 */
export const causeIsFail = <E>(
  self: MicroCause<E>
): self is MicroCause.Fail<E> => self._tag === "Fail"

/**
 * @since 3.4.6
 * @experimental
 * @category MicroCause
 */
export const causeIsDie = <E>(self: MicroCause<E>): self is MicroCause.Die => self._tag === "Die"

/**
 * @since 3.4.6
 * @experimental
 * @category MicroCause
 */
export const causeIsInterrupt = <E>(
  self: MicroCause<E>
): self is MicroCause.Interrupt => self._tag === "Interrupt"

/**
 * @since 3.4.6
 * @experimental
 * @category MicroCause
 */
export const causeSquash = <E>(self: MicroCause<E>): unknown =>
  self._tag === "Fail" ? self.error : self._tag === "Die" ? self.defect : self

/**
 * @since 3.4.6
 * @experimental
 * @category MicroCause
 */
export const causeWithTrace: {
  /**
   * @since 3.4.6
   * @experimental
   * @category MicroCause
   */
  (trace: string): <E>(self: MicroCause<E>) => MicroCause<E>
  /**
   * @since 3.4.6
   * @experimental
   * @category MicroCause
   */
  <E>(self: MicroCause<E>, trace: string): MicroCause<E>
} = dual(2, <E>(self: MicroCause<E>, trace: string): MicroCause<E> => {
  const traces = [...self.traces, trace]
  switch (self._tag) {
    case "Die":
      return causeDie(self.defect, traces)
    case "Interrupt":
      return causeInterrupt(traces)
    case "Fail":
      return causeFail(self.error, traces)
  }
})

// ----------------------------------------------------------------------------
// MicroFiber
// ----------------------------------------------------------------------------

/**
 * @since 3.11.0
 * @experimental
 * @category MicroFiber
 */
export const MicroFiberTypeId = Symbol.for("effect/Micro/MicroFiber")

/**
 * @since 3.11.0
 * @experimental
 * @category MicroFiber
 */
export type MicroFiberTypeId = typeof MicroFiberTypeId

/**
 * @since 3.11.0
 * @experimental
 * @category MicroFiber
 */
export interface MicroFiber<out A, out E = never> {
  readonly [MicroFiberTypeId]: MicroFiber.Variance<A, E>

  readonly currentOpCount: number
  readonly getRef: <I, A>(ref: Context.Reference<I, A>) => A
  readonly context: Context.Context<never>
  readonly addObserver: (cb: (exit: MicroExit<A, E>) => void) => () => void
  readonly unsafeInterrupt: () => void
  readonly unsafePoll: () => MicroExit<A, E> | undefined
}

/**
 * @since 3.11.0
 * @experimental
 * @category MicroFiber
 */
export declare namespace MicroFiber {
  /**
   * @since 3.11.0
   * @experimental
   * @category MicroFiber
   */
  export interface Variance<out A, out E = never> {
    readonly _A: Covariant<A>
    readonly _E: Covariant<E>
  }
}

const fiberVariance = {
  _A: identity,
  _E: identity
}

class MicroFiberImpl<in out A = any, in out E = any> implements MicroFiber<A, E> {
  readonly [MicroFiberTypeId]: MicroFiber.Variance<A, E>

  readonly _stack: Array<Primitive> = []
  readonly _observers: Array<(exit: MicroExit<A, E>) => void> = []
  _exit: MicroExit<A, E> | undefined
  public _children: Set<MicroFiberImpl<any, any>> | undefined

  public currentOpCount = 0

  constructor(
    public context: Context.Context<never>,
    public interruptible = true
  ) {
    this[MicroFiberTypeId] = fiberVariance
  }

  getRef<I, A>(ref: Context.Reference<I, A>): A {
    return InternalContext.unsafeGetReference(this.context, ref)
  }

  addObserver(cb: (exit: MicroExit<A, E>) => void): () => void {
    if (this._exit) {
      cb(this._exit)
      return constVoid
    }
    this._observers.push(cb)
    return () => {
      const index = this._observers.indexOf(cb)
      if (index >= 0) {
        this._observers.splice(index, 1)
      }
    }
  }

  _interrupted = false
  unsafeInterrupt(): void {
    if (this._exit) {
      return
    }
    this._interrupted = true
    if (this.interruptible) {
      this.evaluate(exitInterrupt as any)
    }
  }

  unsafePoll(): MicroExit<A, E> | undefined {
    return this._exit
  }

  evaluate(effect: Primitive): void {
    if (this._exit) {
      return
    } else if (this._yielded !== undefined) {
      const yielded = this._yielded as () => void
      this._yielded = undefined
      yielded()
    }
    const exit = this.runLoop(effect)
    if (exit === Yield) {
      return
    }

    // the interruptChildren middlware is added in Micro.fork, so it can be
    // tree-shaken if not used
    const interruptChildren = fiberMiddleware.interruptChildren && fiberMiddleware.interruptChildren(this)
    if (interruptChildren !== undefined) {
      return this.evaluate(flatMap(interruptChildren, () => exit) as any)
    }

    this._exit = exit
    for (let i = 0; i < this._observers.length; i++) {
      this._observers[i](exit)
    }
    this._observers.length = 0
  }

  runLoop(effect: Primitive): MicroExit<A, E> | Yield {
    let yielding = false
    let current: Primitive | Yield = effect
    this.currentOpCount = 0
    try {
      while (true) {
        this.currentOpCount++
        if (!yielding && this.getRef(CurrentScheduler).shouldYield(this as any)) {
          yielding = true
          const prev = current
          current = flatMap(yieldNow, () => prev as any) as any
        }
        current = (current as any)[evaluate](this)
        if (current === Yield) {
          const yielded = this._yielded!
          if (MicroExitTypeId in yielded) {
            this._yielded = undefined
            return yielded
          }
          return Yield
        }
      }
    } catch (error) {
      if (!hasProperty(current, evaluate)) {
        return exitDie(`MicroFiber.runLoop: Not a valid effect: ${String(current)}`)
      }
      return exitDie(error)
    }
  }

  getCont<S extends successCont | failureCont>(
    symbol: S
  ): Primitive & Record<S, (value: any, fiber: MicroFiberImpl) => Primitive> | undefined {
    while (true) {
      const op = this._stack.pop()
      if (!op) return undefined
      const cont = op[ensureCont] && op[ensureCont](this)
      if (cont) return { [symbol]: cont } as any
      if (op[symbol]) return op as any
    }
  }

  // cancel the yielded operation, or for the yielded exit value
  _yielded: MicroExit<any, any> | (() => void) | undefined = undefined
  yieldWith(value: MicroExit<any, any> | (() => void)): Yield {
    this._yielded = value
    return Yield
  }

  children(): Set<MicroFiber<any, any>> {
    return this._children ??= new Set()
  }
}

const fiberMiddleware = globalValue("effect/Micro/fiberMiddleware", () => ({
  interruptChildren: undefined as ((fiber: MicroFiberImpl) => Micro<void> | undefined) | undefined
}))

const fiberInterruptChildren = (fiber: MicroFiberImpl) => {
  if (fiber._children === undefined || fiber._children.size === 0) {
    return undefined
  }
  return fiberInterruptAll(fiber._children)
}

/**
 * @since 3.11.0
 * @experimental
 * @category MicroFiber
 */
export const fiberAwait = <A, E>(self: MicroFiber<A, E>): Micro<MicroExit<A, E>> =>
  async((resume) => sync(self.addObserver((exit) => resume(succeed(exit)))))

/**
 * @since 3.11.2
 * @experimental
 * @category MicroFiber
 */
export const fiberJoin = <A, E>(self: MicroFiber<A, E>): Micro<A, E> => flatten(fiberAwait(self))

/**
 * @since 3.11.0
 * @experimental
 * @category MicroFiber
 */
export const fiberInterrupt = <A, E>(self: MicroFiber<A, E>): Micro<void> =>
  suspend(() => {
    self.unsafeInterrupt()
    return asVoid(fiberAwait(self))
  })

/**
 * @since 3.11.0
 * @experimental
 * @category MicroFiber
 */
export const fiberInterruptAll = <A extends Iterable<MicroFiber<any, any>>>(fibers: A): Micro<void> =>
  suspend(() => {
    for (const fiber of fibers) fiber.unsafeInterrupt()
    const iter = fibers[Symbol.iterator]()
    const wait: Micro<void> = suspend(() => {
      let result = iter.next()
      while (!result.done) {
        if (result.value.unsafePoll()) {
          result = iter.next()
          continue
        }
        const fiber = result.value
        return async((resume) => {
          fiber.addObserver((_) => {
            resume(wait)
          })
        })
      }
      return exitVoid
    })
    return wait
  })

const identifier = Symbol.for("effect/Micro/identifier")
type identifier = typeof identifier

const args = Symbol.for("effect/Micro/args")
type args = typeof args

const evaluate = Symbol.for("effect/Micro/evaluate")
type evaluate = typeof evaluate

const successCont = Symbol.for("effect/Micro/successCont")
type successCont = typeof successCont

const failureCont = Symbol.for("effect/Micro/failureCont")
type failureCont = typeof failureCont

const ensureCont = Symbol.for("effect/Micro/ensureCont")
type ensureCont = typeof ensureCont

const Yield = Symbol.for("effect/Micro/Yield")
type Yield = typeof Yield

interface Primitive {
  readonly [identifier]: string
  readonly [successCont]: ((value: unknown, fiber: MicroFiberImpl) => Primitive | Yield) | undefined
  readonly [failureCont]:
    | ((cause: MicroCause<unknown>, fiber: MicroFiberImpl) => Primitive | Yield)
    | undefined
  readonly [ensureCont]:
    | ((fiber: MicroFiberImpl) =>
      | ((value: unknown, fiber: MicroFiberImpl) => Primitive | Yield)
      | undefined)
    | undefined
  [evaluate](fiber: MicroFiberImpl): Primitive | Yield
}

const microVariance = {
  _A: identity,
  _E: identity,
  _R: identity
}

const MicroProto = {
  ...Effectable.EffectPrototype,
  _op: "Micro",
  [TypeId]: microVariance,
  pipe() {
    return pipeArguments(this, arguments)
  },
  [Symbol.iterator]() {
    return new SingleShotGen(new YieldWrap(this)) as any
  },
  toJSON(this: Primitive) {
    return {
      _id: "Micro",
      op: this[identifier],
      ...(args in this ? { args: this[args] } : undefined)
    }
  },
  toString() {
    return format(this)
  },
  [NodeInspectSymbol]() {
    return format(this)
  }
}

function defaultEvaluate(_fiber: MicroFiberImpl): Primitive | Yield {
  return exitDie(`Micro.evaluate: Not implemented`) as any
}

const makePrimitiveProto = <Op extends string>(options: {
  readonly op: Op
  readonly eval?: (fiber: MicroFiberImpl) => Primitive | Micro<any, any, any> | Yield
  readonly contA?: (this: Primitive, value: any, fiber: MicroFiberImpl) => Primitive | Micro<any, any, any> | Yield
  readonly contE?: (
    this: Primitive,
    cause: MicroCause<any>,
    fiber: MicroFiberImpl
  ) => Primitive | Micro<any, any, any> | Yield
  readonly ensure?: (this: Primitive, fiber: MicroFiberImpl) => void | ((value: any, fiber: MicroFiberImpl) => void)
}): Primitive => ({
  ...MicroProto,
  [identifier]: options.op,
  [evaluate]: options.eval ?? defaultEvaluate,
  [successCont]: options.contA,
  [failureCont]: options.contE,
  [ensureCont]: options.ensure
} as any)

const makePrimitive = <Fn extends (...args: Array<any>) => any, Single extends boolean = true>(options: {
  readonly op: string
  readonly single?: Single
  readonly eval?: (
    this: Primitive & { readonly [args]: Single extends true ? Parameters<Fn>[0] : Parameters<Fn> },
    fiber: MicroFiberImpl
  ) => Primitive | Micro<any, any, any> | Yield
  readonly contA?: (
    this: Primitive & { readonly [args]: Single extends true ? Parameters<Fn>[0] : Parameters<Fn> },
    value: any,
    fiber: MicroFiberImpl
  ) => Primitive | Micro<any, any, any> | Yield
  readonly contE?: (
    this: Primitive & { readonly [args]: Single extends true ? Parameters<Fn>[0] : Parameters<Fn> },
    cause: MicroCause<any>,
    fiber: MicroFiberImpl
  ) => Primitive | Micro<any, any, any> | Yield
  readonly ensure?: (
    this: Primitive & { readonly [args]: Single extends true ? Parameters<Fn>[0] : Parameters<Fn> },
    fiber: MicroFiberImpl
  ) => void | ((value: any, fiber: MicroFiberImpl) => void)
}): Fn => {
  const Proto = makePrimitiveProto(options as any)
  return function() {
    const self = Object.create(Proto)
    self[args] = options.single === false ? arguments : arguments[0]
    return self
  } as Fn
}

const makeExit = <Fn extends (...args: Array<any>) => any, Prop extends string>(options: {
  readonly op: "Success" | "Failure"
  readonly prop: Prop
  readonly eval: (
    this:
      & MicroExit<unknown, unknown>
      & { [args]: Parameters<Fn>[0] },
    fiber: MicroFiberImpl<unknown, unknown>
  ) => Primitive | Yield
}): Fn => {
  const Proto = {
    ...makePrimitiveProto(options),
    [MicroExitTypeId]: MicroExitTypeId,
    _tag: options.op,
    get [options.prop](): any {
      return (this as any)[args]
    },
    toJSON(this: any) {
      return {
        _id: "MicroExit",
        _tag: options.op,
        [options.prop]: this[args]
      }
    },
    [Equal.symbol](this: any, that: any): boolean {
      return isMicroExit(that) && that._tag === options.op &&
        Equal.equals(this[args], (that as any)[args])
    },
    [Hash.symbol](this: any): number {
      return Hash.cached(this, Hash.combine(Hash.string(options.op))(Hash.hash(this[args])))
    }
  }
  return function(value: unknown) {
    const self = Object.create(Proto)
    self[args] = value
    self[successCont] = undefined
    self[failureCont] = undefined
    self[ensureCont] = undefined
    return self
  } as Fn
}

/**
 * Creates a `Micro` effect that will succeed with the specified constant value.
 *
 * @since 3.4.0
 * @experimental
 * @category constructors
 */
export const succeed: <A>(value: A) => Micro<A> = makeExit({
  op: "Success",
  prop: "value",
  eval(fiber) {
    const cont = fiber.getCont(successCont)
    return cont ? cont[successCont](this[args], fiber) : fiber.yieldWith(this)
  }
})

/**
 * Creates a `Micro` effect that will fail with the specified `MicroCause`.
 *
 * @since 3.4.6
 * @experimental
 * @category constructors
 */
export const failCause: <E>(cause: MicroCause<E>) => Micro<never, E> = makeExit({
  op: "Failure",
  prop: "cause",
  eval(fiber) {
    let cont = fiber.getCont(failureCont)
    while (causeIsInterrupt(this[args]) && cont && fiber.interruptible) {
      cont = fiber.getCont(failureCont)
    }
    return cont ? cont[failureCont](this[args], fiber) : fiber.yieldWith(this)
  }
})

/**
 * Creates a `Micro` effect that fails with the given error.
 *
 * This results in a `Fail` variant of the `MicroCause` type, where the error is
 * tracked at the type level.
 *
 * @since 3.4.0
 * @experimental
 * @category constructors
 */
export const fail = <E>(error: E): Micro<never, E> => failCause(causeFail(error))

/**
 * Creates a `Micro` effect that succeeds with a lazily evaluated value.
 *
 * If the evaluation of the value throws an error, the effect will fail with a
 * `Die` variant of the `MicroCause` type.
 *
 * @since 3.4.0
 * @experimental
 * @category constructors
 */
export const sync: <A>(evaluate: LazyArg<A>) => Micro<A> = makePrimitive({
  op: "Sync",
  eval(fiber): Primitive | Yield {
    const value = this[args]()
    const cont = fiber.getCont(successCont)
    return cont ? cont[successCont](value, fiber) : fiber.yieldWith(exitSucceed(value))
  }
})

/**
 * Lazily creates a `Micro` effect from the given side-effect.
 *
 * @since 3.4.0
 * @experimental
 * @category constructors
 */
export const suspend: <A, E, R>(evaluate: LazyArg<Micro<A, E, R>>) => Micro<A, E, R> = makePrimitive({
  op: "Suspend",
  eval(_fiber) {
    return this[args]()
  }
})

/**
 * Pause the execution of the current `Micro` effect, and resume it on the next
 * scheduler tick.
 *
 * @since 3.4.0
 * @experimental
 * @category constructors
 */
export const yieldNowWith: (priority?: number) => Micro<void> = makePrimitive({
  op: "Yield",
  eval(fiber) {
    let resumed = false
    fiber.getRef(CurrentScheduler).scheduleTask(() => {
      if (resumed) return
      fiber.evaluate(exitVoid as any)
    }, this[args] ?? 0)
    return fiber.yieldWith(() => {
      resumed = true
    })
  }
})

/**
 * Pause the execution of the current `Micro` effect, and resume it on the next
 * scheduler tick.
 *
 * @since 3.4.0
 * @experimental
 * @category constructors
 */
export const yieldNow: Micro<void> = yieldNowWith(0)

/**
 * Creates a `Micro` effect that will succeed with the value wrapped in `Some`.
 *
 * @since 3.4.0
 * @experimental
 * @category constructors
 */
export const succeedSome = <A>(a: A): Micro<Option.Option<A>> => succeed(Option.some(a))

/**
 * Creates a `Micro` effect that succeeds with `None`.
 *
 * @since 3.4.0
 * @experimental
 * @category constructors
 */
export const succeedNone: Micro<Option.Option<never>> = succeed(Option.none())

/**
 * Creates a `Micro` effect that will fail with the lazily evaluated `MicroCause`.
 *
 * @since 3.4.0
 * @experimental
 * @category constructors
 */
export const failCauseSync = <E>(evaluate: LazyArg<MicroCause<E>>): Micro<never, E> =>
  suspend(() => failCause(evaluate()))

/**
 * Creates a `Micro` effect that will die with the specified error.
 *
 * This results in a `Die` variant of the `MicroCause` type, where the error is
 * not tracked at the type level.
 *
 * @since 3.4.0
 * @experimental
 * @category constructors
 */
export const die = (defect: unknown): Micro<never> => exitDie(defect)

/**
 * Creates a `Micro` effect that will fail with the lazily evaluated error.
 *
 * This results in a `Fail` variant of the `MicroCause` type, where the error is
 * tracked at the type level.
 *
 * @since 3.4.6
 * @experimental
 * @category constructors
 */
export const failSync = <E>(error: LazyArg<E>): Micro<never, E> => suspend(() => fail(error()))

/**
 * Converts an `Option` into a `Micro` effect, that will fail with
 * `NoSuchElementException` if the option is `None`. Otherwise, it will succeed with the
 * value of the option.
 *
 * @since 3.4.0
 * @experimental
 * @category constructors
 */
export const fromOption = <A>(option: Option.Option<A>): Micro<A, NoSuchElementException> =>
  option._tag === "Some" ? succeed(option.value) : fail(new NoSuchElementException({}))

/**
 * Converts an `Either` into a `Micro` effect, that will fail with the left side
 * of the either if it is a `Left`. Otherwise, it will succeed with the right
 * side of the either.
 *
 * @since 3.4.0
 * @experimental
 * @category constructors
 */
export const fromEither = <R, L>(either: Either.Either<R, L>): Micro<R, L> =>
  either._tag === "Right" ? succeed(either.right) : fail(either.left)

const void_: Micro<void> = succeed(void 0)
export {
  /**
   * A `Micro` effect that will succeed with `void` (`undefined`).
   *
   * @since 3.4.0
   * @experimental
   * @category constructors
   */
  void_ as void
}

const try_ = <A, E>(options: {
  try: LazyArg<A>
  catch: (error: unknown) => E
}): Micro<A, E> =>
  suspend(() => {
    try {
      return succeed(options.try())
    } catch (err) {
      return fail(options.catch(err))
    }
  })
export {
  /**
   * The `Micro` equivalent of a try / catch block, which allows you to map
   * thrown errors to a specific error type.
   *
   * @example
   * ```ts
   * import { Micro } from "effect"
   *
   * Micro.try({
   *   try: () => throw new Error("boom"),
   *   catch: (cause) => new Error("caught", { cause })
   * })
   * ```
   *
   * @since 3.4.0
   * @experimental
   * @category constructors
   */
  try_ as try
}

/**
 * Wrap a `Promise` into a `Micro` effect.
 *
 * Any errors will result in a `Die` variant of the `MicroCause` type, where the
 * error is not tracked at the type level.
 *
 * @since 3.4.0
 * @experimental
 * @category constructors
 */
export const promise = <A>(evaluate: (signal: AbortSignal) => PromiseLike<A>): Micro<A> =>
  asyncOptions<A>(function(resume, signal) {
    evaluate(signal!).then(
      (a) => resume(succeed(a)),
      (e) => resume(die(e))
    )
  }, evaluate.length !== 0)

/**
 * Wrap a `Promise` into a `Micro` effect. Any errors will be caught and
 * converted into a specific error type.
 *
 * @example
 * ```ts
 * import { Micro } from "effect"
 *
 * Micro.tryPromise({
 *   try: () => Promise.resolve("success"),
 *   catch: (cause) => new Error("caught", { cause })
 * })
 * ```
 *
 * @since 3.4.0
 * @experimental
 * @category constructors
 */
export const tryPromise = <A, E>(options: {
  readonly try: (signal: AbortSignal) => PromiseLike<A>
  readonly catch: (error: unknown) => E
}): Micro<A, E> =>
  asyncOptions<A, E>(function(resume, signal) {
    try {
      options.try(signal!).then(
        (a) => resume(succeed(a)),
        (e) => resume(fail(options.catch(e)))
      )
    } catch (err) {
      resume(fail(options.catch(err)))
    }
  }, options.try.length !== 0)

/**
 * Create a `Micro` effect using the current `MicroFiber`.
 *
 * @since 3.4.0
 * @experimental
 * @category constructors
 */
export const withMicroFiber: <A, E = never, R = never>(
  evaluate: (fiber: MicroFiberImpl<A, E>) => Micro<A, E, R>
) => Micro<A, E, R> = makePrimitive({
  op: "WithMicroFiber",
  eval(fiber) {
    return this[args](fiber)
  }
})

/**
 * Flush any yielded effects that are waiting to be executed.
 *
 * @since 3.4.0
 * @experimental
 * @category constructors
 */
export const yieldFlush: Micro<void> = withMicroFiber((fiber) => {
  fiber.getRef(CurrentScheduler).flush()
  return exitVoid
})

const asyncOptions: <A, E = never, R = never>(
  register: (
    resume: (effect: Micro<A, E, R>) => void,
    signal?: AbortSignal
  ) => void | Micro<void, never, R>,
  withSignal: boolean
) => Micro<A, E, R> = makePrimitive({
  op: "Async",
  single: false,
  eval(fiber) {
    const register = this[args][0]
    let resumed = false
    let yielded: boolean | Primitive = false
    const controller = this[args][1] ? new AbortController() : undefined
    const onCancel = register((effect) => {
      if (resumed) return
      resumed = true
      if (yielded) {
        fiber.evaluate(effect as any)
      } else {
        yielded = effect as any
      }
    }, controller?.signal)
    if (yielded !== false) return yielded
    yielded = true
    fiber._yielded = () => {
      resumed = true
    }
    if (controller === undefined && onCancel === undefined) {
      return Yield
    }
    fiber._stack.push(asyncFinalizer(() => {
      resumed = true
      controller?.abort()
      return onCancel ?? exitVoid
    }))
    return Yield
  }
})
const asyncFinalizer: (onInterrupt: () => Micro<void, any, any>) => Primitive = makePrimitive({
  op: "AsyncFinalizer",
  ensure(fiber) {
    if (fiber.interruptible) {
      fiber.interruptible = false
      fiber._stack.push(setInterruptible(true))
    }
  },
  contE(cause, _fiber) {
    return causeIsInterrupt(cause)
      ? flatMap(this[args](), () => failCause(cause))
      : failCause(cause)
  }
})

/**
 * Create a `Micro` effect from an asynchronous computation.
 *
 * You can return a cleanup effect that will be run when the effect is aborted.
 * It is also passed an `AbortSignal` that is triggered when the effect is
 * aborted.
 *
 * @since 3.4.0
 * @experimental
 * @category constructors
 */
export const async = <A, E = never, R = never>(
  register: (
    resume: (effect: Micro<A, E, R>) => void,
    signal: AbortSignal
  ) => void | Micro<void, never, R>
): Micro<A, E, R> => asyncOptions(register as any, register.length >= 2)

/**
 * A `Micro` that will never succeed or fail. It wraps `setInterval` to prevent
 * the Javascript runtime from exiting.
 *
 * @since 3.4.0
 * @experimental
 * @category constructors
 */
export const never: Micro<never> = async<never>(function() {
  const interval = setInterval(constVoid, 2147483646)
  return sync(() => clearInterval(interval))
})

/**
 * @since 3.4.0
 * @experimental
 * @category constructors
 */
export const gen = <Self, Eff extends YieldWrap<Micro<any, any, any>>, AEff>(
  ...args:
    | [self: Self, body: (this: Self) => Generator<Eff, AEff, never>]
    | [body: () => Generator<Eff, AEff, never>]
): Micro<
  AEff,
  [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Micro<infer _A, infer E, infer _R>>] ? E : never,
  [Eff] extends [never] ? never : [Eff] extends [YieldWrap<Micro<infer _A, infer _E, infer R>>] ? R : never
> => suspend(() => fromIterator(args.length === 1 ? args[0]() : args[1].call(args[0]) as any))

const fromIterator: (
  iterator: Iterator<any, YieldWrap<Micro<any, any, any>>>
) => Micro<any, any, any> = makePrimitive({
  op: "Iterator",
  contA(value, fiber) {
    const state = this[args].next(value)
    if (state.done) return succeed(state.value)
    fiber._stack.push(this)
    return yieldWrapGet(state.value)
  },
  eval(this: any, fiber: MicroFiberImpl) {
    return this[successCont](undefined, fiber)
  }
})

// ----------------------------------------------------------------------------
// mapping & sequencing
// ----------------------------------------------------------------------------

/**
 * Create a `Micro` effect that will replace the success value of the given
 * effect.
 *
 * @since 3.4.0
 * @experimental
 * @category mapping & sequencing
 */
export const as: {
  // ----------------------------------------------------------------------------
  // mapping & sequencing
  // ----------------------------------------------------------------------------

  /**
   * Create a `Micro` effect that will replace the success value of the given
   * effect.
   *
   * @since 3.4.0
   * @experimental
   * @category mapping & sequencing
   */
  <A, B>(value: B): <E, R>(self: Micro<A, E, R>) => Micro<B, E, R>
  // ----------------------------------------------------------------------------
  // mapping & sequencing
  // ----------------------------------------------------------------------------

  /**
   * Create a `Micro` effect that will replace the success value of the given
   * effect.
   *
   * @since 3.4.0
   * @experimental
   * @category mapping & sequencing
   */
  <A, E, R, B>(self: Micro<A, E, R>, value: B): Micro<B, E, R>
} = dual(2, <A, E, R, B>(self: Micro<A, E, R>, value: B): Micro<B, E, R> => map(self, (_) => value))

/**
 * Wrap the success value of this `Micro` effect in a `Some`.
 *
 * @since 3.4.0
 * @experimental
 * @category mapping & sequencing
 */
export const asSome = <A, E, R>(self: Micro<A, E, R>): Micro<Option.Option<A>, E, R> => map(self, Option.some)

/**
 * Swap the error and success types of the `Micro` effect.
 *
 * @since 3.4.0
 * @experimental
 * @category mapping & sequencing
 */
export const flip = <A, E, R>(self: Micro<A, E, R>): Micro<E, A, R> =>
  matchEffect(self, {
    onFailure: succeed,
    onSuccess: fail
  })

/**
 * A more flexible version of `flatMap` that combines `map` and `flatMap` into a
 * single API.
 *
 * It also lets you directly pass a `Micro` effect, which will be executed after
 * the current effect.
 *
 * @since 3.4.0
 * @experimental
 * @category mapping & sequencing
 */
export const andThen: {
  /**
   * A more flexible version of `flatMap` that combines `map` and `flatMap` into a
   * single API.
   *
   * It also lets you directly pass a `Micro` effect, which will be executed after
   * the current effect.
   *
   * @since 3.4.0
   * @experimental
   * @category mapping & sequencing
   */
  <A, X>(f: (a: A) => X): <E, R>(
    self: Micro<A, E, R>
  ) => [X] extends [Micro<infer A1, infer E1, infer R1>] ? Micro<A1, E | E1, R | R1>
    : Micro<X, E, R>
  /**
   * A more flexible version of `flatMap` that combines `map` and `flatMap` into a
   * single API.
   *
   * It also lets you directly pass a `Micro` effect, which will be executed after
   * the current effect.
   *
   * @since 3.4.0
   * @experimental
   * @category mapping & sequencing
   */
  <X>(f: NotFunction<X>): <A, E, R>(
    self: Micro<A, E, R>
  ) => [X] extends [Micro<infer A1, infer E1, infer R1>] ? Micro<A1, E | E1, R | R1>
    : Micro<X, E, R>
  /**
   * A more flexible version of `flatMap` that combines `map` and `flatMap` into a
   * single API.
   *
   * It also lets you directly pass a `Micro` effect, which will be executed after
   * the current effect.
   *
   * @since 3.4.0
   * @experimental
   * @category mapping & sequencing
   */
  <A, E, R, X>(self: Micro<A, E, R>, f: (a: A) => X): [X] extends [Micro<infer A1, infer E1, infer R1>] ? Micro<A1, E | E1, R | R1>
    : Micro<X, E, R>
  /**
   * A more flexible version of `flatMap` that combines `map` and `flatMap` into a
   * single API.
   *
   * It also lets you directly pass a `Micro` effect, which will be executed after
   * the current effect.
   *
   * @since 3.4.0
   * @experimental
   * @category mapping & sequencing
   */
  <A, E, R, X>(self: Micro<A, E, R>, f: NotFunction<X>): [X] extends [Micro<infer A1, infer E1, infer R1>] ? Micro<A1, E | E1, R | R1>
    : Micro<X, E, R>
} = dual(
  2,
  <A, E, R, B, E2, R2>(self: Micro<A, E, R>, f: any): Micro<B, E | E2, R | R2> =>
    flatMap(self, (a) => {
      const value = isMicro(f) ? f : typeof f === "function" ? f(a) : f
      return isMicro(value) ? value : succeed(value)
    })
)

/**
 * Execute a side effect from the success value of the `Micro` effect.
 *
 * It is similar to the `andThen` api, but the success value is ignored.
 *
 * @since 3.4.0
 * @experimental
 * @category mapping & sequencing
 */
export const tap: {
  /**
   * Execute a side effect from the success value of the `Micro` effect.
   *
   * It is similar to the `andThen` api, but the success value is ignored.
   *
   * @since 3.4.0
   * @experimental
   * @category mapping & sequencing
   */
  <A, X>(f: (a: NoInfer<A>) => X): <E, R>(
    self: Micro<A, E, R>
  ) => [X] extends [Micro<infer _A1, infer E1, infer R1>] ? Micro<A, E | E1, R | R1>
    : Micro<A, E, R>
  /**
   * Execute a side effect from the success value of the `Micro` effect.
   *
   * It is similar to the `andThen` api, but the success value is ignored.
   *
   * @since 3.4.0
   * @experimental
   * @category mapping & sequencing
   */
  <X>(f: NotFunction<X>): <A, E, R>(
    self: Micro<A, E, R>
  ) => [X] extends [Micro<infer _A1, infer E1, infer R1>] ? Micro<A, E | E1, R | R1>
    : Micro<A, E, R>
  /**
   * Execute a side effect from the success value of the `Micro` effect.
   *
   * It is similar to the `andThen` api, but the success value is ignored.
   *
   * @since 3.4.0
   * @experimental
   * @category mapping & sequencing
   */
  <A, E, R, X>(self: Micro<A, E, R>, f: (a: NoInfer<A>) => X): [X] extends [Micro<infer _A1, infer E1, infer R1>] ? Micro<A, E | E1, R | R1>
    : Micro<A, E, R>
  /**
   * Execute a side effect from the success value of the `Micro` effect.
   *
   * It is similar to the `andThen` api, but the success value is ignored.
   *
   * @since 3.4.0
   * @experimental
   * @category mapping & sequencing
   */
  <A, E, R, X>(self: Micro<A, E, R>, f: NotFunction<X>): [X] extends [Micro<infer _A1, infer E1, infer R1>] ? Micro<A, E | E1, R | R1>
    : Micro<A, E, R>
} = dual(
  2,
  <A, E, R, B, E2, R2>(self: Micro<A, E, R>, f: (a: A) => Micro<B, E2, R2>): Micro<A, E | E2, R | R2> =>
    flatMap(self, (a) => {
      const value = isMicro(f) ? f : typeof f === "function" ? f(a) : f
      return isMicro(value) ? as(value, a) : succeed(a)
    })
)

/**
 * Replace the success value of the `Micro` effect with `void`.
 *
 * @since 3.4.0
 * @experimental
 * @category mapping & sequencing
 */
export const asVoid = <A, E, R>(self: Micro<A, E, R>): Micro<void, E, R> => flatMap(self, (_) => exitVoid)

/**
 * Access the `MicroExit` of the given `Micro` effect.
 *
 * @since 3.4.6
 * @experimental
 * @category mapping & sequencing
 */
export const exit = <A, E, R>(self: Micro<A, E, R>): Micro<MicroExit<A, E>, never, R> =>
  matchCause(self, {
    onFailure: exitFailCause,
    onSuccess: exitSucceed
  })

/**
 * Replace the error type of the given `Micro` with the full `MicroCause` object.
 *
 * @since 3.4.0
 * @experimental
 * @category mapping & sequencing
 */
export const sandbox = <A, E, R>(self: Micro<A, E, R>): Micro<A, MicroCause<E>, R> => catchAllCause(self, fail)

/**
 * Returns an effect that races all the specified effects,
 * yielding the value of the first effect to succeed with a value. Losers of
 * the race will be interrupted immediately
 *
 * @since 3.4.0
 * @experimental
 * @category sequencing
 */
export const raceAll = <Eff extends Micro<any, any, any>>(
  all: Iterable<Eff>
): Micro<Micro.Success<Eff>, Micro.Error<Eff>, Micro.Context<Eff>> =>
  withMicroFiber((parent) =>
    async((resume) => {
      const effects = Arr.fromIterable(all)
      const len = effects.length
      let doneCount = 0
      let done = false
      const fibers = new Set<MicroFiber<any, any>>()
      const causes: Array<MicroCause<any>> = []
      const onExit = (exit: MicroExit<any, any>) => {
        doneCount++
        if (exit._tag === "Failure") {
          causes.push(exit.cause)
          if (doneCount >= len) {
            resume(failCause(causes[0]))
          }
          return
        }
        done = true
        resume(fibers.size === 0 ? exit : flatMap(uninterruptible(fiberInterruptAll(fibers)), () => exit))
      }

      for (let i = 0; i < len; i++) {
        if (done) break
        const fiber = unsafeFork(parent, interruptible(effects[i]), true, true)
        fibers.add(fiber)
        fiber.addObserver((exit) => {
          fibers.delete(fiber)
          onExit(exit)
        })
      }

      return fiberInterruptAll(fibers)
    })
  )

/**
 * Returns an effect that races all the specified effects,
 * yielding the value of the first effect to succeed or fail. Losers of
 * the race will be interrupted immediately.
 *
 * @since 3.4.0
 * @experimental
 * @category sequencing
 */
export const raceAllFirst = <Eff extends Micro<any, any, any>>(
  all: Iterable<Eff>
): Micro<Micro.Success<Eff>, Micro.Error<Eff>, Micro.Context<Eff>> =>
  withMicroFiber((parent) =>
    async((resume) => {
      let done = false
      const fibers = new Set<MicroFiber<any, any>>()
      const onExit = (exit: MicroExit<any, any>) => {
        done = true
        resume(fibers.size === 0 ? exit : flatMap(fiberInterruptAll(fibers), () => exit))
      }

      for (const effect of all) {
        if (done) break
        const fiber = unsafeFork(parent, interruptible(effect), true, true)
        fibers.add(fiber)
        fiber.addObserver((exit) => {
          fibers.delete(fiber)
          onExit(exit)
        })
      }

      return fiberInterruptAll(fibers)
    })
  )

/**
 * Returns an effect that races two effects, yielding the value of the first
 * effect to succeed. Losers of the race will be interrupted immediately.
 *
 * @since 3.4.0
 * @experimental
 * @category sequencing
 */
export const race: {
  /**
   * Returns an effect that races two effects, yielding the value of the first
   * effect to succeed. Losers of the race will be interrupted immediately.
   *
   * @since 3.4.0
   * @experimental
   * @category sequencing
   */
  <A2, E2, R2>(that: Micro<A2, E2, R2>): <A, E, R>(self: Micro<A, E, R>) => Micro<A | A2, E | E2, R | R2>
  /**
   * Returns an effect that races two effects, yielding the value of the first
   * effect to succeed. Losers of the race will be interrupted immediately.
   *
   * @since 3.4.0
   * @experimental
   * @category sequencing
   */
  <A, E, R, A2, E2, R2>(self: Micro<A, E, R>, that: Micro<A2, E2, R2>): Micro<A | A2, E | E2, R | R2>
} = dual(
  2,
  <A, E, R, A2, E2, R2>(self: Micro<A, E, R>, that: Micro<A2, E2, R2>): Micro<A | A2, E | E2, R | R2> =>
    raceAll([self, that])
)

/**
 * Returns an effect that races two effects, yielding the value of the first
 * effect to succeed *or* fail. Losers of the race will be interrupted immediately.
 *
 * @since 3.4.0
 * @experimental
 * @category sequencing
 */
export const raceFirst: {
  /**
   * Returns an effect that races two effects, yielding the value of the first
   * effect to succeed *or* fail. Losers of the race will be interrupted immediately.
   *
   * @since 3.4.0
   * @experimental
   * @category sequencing
   */
  <A2, E2, R2>(that: Micro<A2, E2, R2>): <A, E, R>(self: Micro<A, E, R>) => Micro<A | A2, E | E2, R | R2>
  /**
   * Returns an effect that races two effects, yielding the value of the first
   * effect to succeed *or* fail. Losers of the race will be interrupted immediately.
   *
   * @since 3.4.0
   * @experimental
   * @category sequencing
   */
  <A, E, R, A2, E2, R2>(self: Micro<A, E, R>, that: Micro<A2, E2, R2>): Micro<A | A2, E | E2, R | R2>
} = dual(
  2,
  <A, E, R, A2, E2, R2>(self: Micro<A, E, R>, that: Micro<A2, E2, R2>): Micro<A | A2, E | E2, R | R2> =>
    raceAllFirst([self, that])
)

/**
 * Map the success value of this `Micro` effect to another `Micro` effect, then
 * flatten the result.
 *
 * @since 3.4.0
 * @experimental
 * @category mapping & sequencing
 */
export const flatMap: {
  /**
   * Map the success value of this `Micro` effect to another `Micro` effect, then
   * flatten the result.
   *
   * @since 3.4.0
   * @experimental
   * @category mapping & sequencing
   */
  <A, B, E2, R2>(f: (a: A) => Micro<B, E2, R2>): <E, R>(self: Micro<A, E, R>) => Micro<B, E | E2, R | R2>
  /**
   * Map the success value of this `Micro` effect to another `Micro` effect, then
   * flatten the result.
   *
   * @since 3.4.0
   * @experimental
   * @category mapping & sequencing
   */
  <A, E, R, B, E2, R2>(self: Micro<A, E, R>, f: (a: A) => Micro<B, E2, R2>): Micro<B, E | E2, R | R2>
} = dual(
  2,
  <A, E, R, B, E2, R2>(
    self: Micro<A, E, R>,
    f: (a: A) => Micro<B, E2, R2>
  ): Micro<B, E | E2, R | R2> => {
    const onSuccess = Object.create(OnSuccessProto)
    onSuccess[args] = self
    onSuccess[successCont] = f
    return onSuccess
  }
)
const OnSuccessProto = makePrimitiveProto({
  op: "OnSuccess",
  eval(this: any, fiber: MicroFiberImpl): Primitive {
    fiber._stack.push(this)
    return this[args]
  }
})

// ----------------------------------------------------------------------------
// mapping & sequencing
// ----------------------------------------------------------------------------

/**
 * Flattens any nested `Micro` effects, merging the error and requirement types.
 *
 * @since 3.4.0
 * @experimental
 * @category mapping & sequencing
 */
export const flatten = <A, E, R, E2, R2>(
  self: Micro<Micro<A, E, R>, E2, R2>
): Micro<A, E | E2, R | R2> => flatMap(self, identity)

/**
 * Transforms the success value of the `Micro` effect with the specified
 * function.
 *
 * @since 3.4.0
 * @experimental
 * @category mapping & sequencing
 */
export const map: {
  /**
   * Transforms the success value of the `Micro` effect with the specified
   * function.
   *
   * @since 3.4.0
   * @experimental
   * @category mapping & sequencing
   */
  <A, B>(f: (a: A) => B): <E, R>(self: Micro<A, E, R>) => Micro<B, E, R>
  /**
   * Transforms the success value of the `Micro` effect with the specified
   * function.
   *
   * @since 3.4.0
   * @experimental
   * @category mapping & sequencing
   */
  <A, E, R, B>(self: Micro<A, E, R>, f: (a: A) => B): Micro<B, E, R>
} = dual(
  2,
  <A, E, R, B>(self: Micro<A, E, R>, f: (a: A) => B): Micro<B, E, R> => flatMap(self, (a) => succeed(f(a)))
)

// ----------------------------------------------------------------------------
// MicroExit
// ----------------------------------------------------------------------------

/**
 * The `MicroExit` type is used to represent the result of a `Micro` computation. It
 * can either be successful, containing a value of type `A`, or it can fail,
 * containing an error of type `E` wrapped in a `MicroCause`.
 *
 * @since 3.4.6
 * @experimental
 * @category MicroExit
 */
export type MicroExit<A, E = never> =
  | MicroExit.Success<A, E>
  | MicroExit.Failure<A, E>

/**
 * @since 3.4.6
 * @experimental
 * @category MicroExit
 */
export declare namespace MicroExit {
  /**
   * @since 3.4.6
   * @experimental
   * @category MicroExit
   */
  export interface Proto<out A, out E = never> extends Micro<A, E> {
    readonly [MicroExitTypeId]: MicroExitTypeId
  }

  /**
   * @since 3.4.6
   * @experimental
   * @category MicroExit
   */
  export interface Success<out A, out E> extends Proto<A, E> {
    readonly _tag: "Success"
    readonly value: A
  }

  /**
   * @since 3.4.6
   * @experimental
   * @category MicroExit
   */
  export interface Failure<out A, out E> extends Proto<A, E> {
    readonly _tag: "Failure"
    readonly cause: MicroCause<E>
  }
}

/**
 * @since 3.4.6
 * @experimental
 * @category MicroExit
 */
export const isMicroExit = (u: unknown): u is MicroExit<unknown, unknown> => hasProperty(u, MicroExitTypeId)

/**
 * @since 3.4.6
 * @experimental
 * @category MicroExit
 */
export const exitSucceed: <A>(a: A) => MicroExit<A, never> = succeed as any

/**
 * @since 3.4.6
 * @experimental
 * @category MicroExit
 */
export const exitFailCause: <E>(cause: MicroCause<E>) => MicroExit<never, E> = failCause as any

/**
 * @since 3.4.6
 * @experimental
 * @category MicroExit
 */
export const exitInterrupt: MicroExit<never> = exitFailCause(causeInterrupt())

/**
 * @since 3.4.6
 * @experimental
 * @category MicroExit
 */
export const exitFail = <E>(e: E): MicroExit<never, E> => exitFailCause(causeFail(e))

/**
 * @since 3.4.6
 * @experimental
 * @category MicroExit
 */
export const exitDie = (defect: unknown): MicroExit<never> => exitFailCause(causeDie(defect))

/**
 * @since 3.4.6
 * @experimental
 * @category MicroExit
 */
export const exitIsSuccess = <A, E>(
  self: MicroExit<A, E>
): self is MicroExit.Success<A, E> => self._tag === "Success"

/**
 * @since 3.4.6
 * @experimental
 * @category MicroExit
 */