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Viewing / Editing File: Option.js

import * as Equal from "./Equal.js";
import * as Equivalence from "./Equivalence.js";
import { constNull, constUndefined, dual, identity, isFunction } from "./Function.js";
import * as doNotation from "./internal/doNotation.js";
import * as either from "./internal/either.js";
import * as option from "./internal/option.js";
import * as order from "./Order.js";
import * as Gen from "./Utils.js";
/**
 * @category Symbols
 * @since 2.0.0
 */
export const TypeId = /*#__PURE__*/Symbol.for("effect/Option");
/**
 * Represents the absence of a value by creating an empty `Option`.
 *
 * `Option.none` returns an `Option<never>`, which is a subtype of `Option<A>`.
 * This means you can use it in place of any `Option<A>` regardless of the type
 * `A`.
 *
 * **Example** (Creating an Option with No Value)
 *
 * ```ts
 * import { Option } from "effect"
 *
 * // An Option holding no value
 * //
 * //      ┌─── Option<never>
 * //      ▼
 * const noValue = Option.none()
 *
 * console.log(noValue)
 * // Output: { _id: 'Option', _tag: 'None' }
 * ```
 *
 * @see {@link some} for the opposite operation.
 *
 * @category Constructors
 * @since 2.0.0
 */
export const none = () => option.none;
/**
 * Wraps the given value into an `Option` to represent its presence.
 *
 * **Example** (Creating an Option with a Value)
 *
 * ```ts
 * import { Option } from "effect"
 *
 * // An Option holding the number 1
 * //
 * //      ┌─── Option<number>
 * //      ▼
 * const value = Option.some(1)
 *
 * console.log(value)
 * // Output: { _id: 'Option', _tag: 'Some', value: 1 }
 * ```
 *
 * @see {@link none} for the opposite operation.
 *
 * @category Constructors
 * @since 2.0.0
 */
export const some = option.some;
/**
 * Determines whether the given value is an `Option`.
 *
 * **Details**
 *
 * This function checks if a value is an instance of `Option`. It returns `true`
 * if the value is either `Option.some` or `Option.none`, and `false` otherwise.
 * This is particularly useful when working with unknown values or when you need
 * to ensure type safety in your code.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * console.log(Option.isOption(Option.some(1)))
 * // Output: true
 *
 * console.log(Option.isOption(Option.none()))
 * // Output: true
 *
 * console.log(Option.isOption({}))
 * // Output: false
 * ```
 *
 * @category Guards
 * @since 2.0.0
 */
export const isOption = option.isOption;
/**
 * Checks whether an `Option` represents the absence of a value (`None`).
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * console.log(Option.isNone(Option.some(1)))
 * // Output: false
 *
 * console.log(Option.isNone(Option.none()))
 * // Output: true
 * ```
 *
 * @see {@link isSome} for the opposite check.
 *
 * @category Guards
 * @since 2.0.0
 */
export const isNone = option.isNone;
/**
 * Checks whether an `Option` contains a value (`Some`).
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * console.log(Option.isSome(Option.some(1)))
 * // Output: true
 *
 * console.log(Option.isSome(Option.none()))
 * // Output: false
 * ```
 *
 * @see {@link isNone} for the opposite check.
 *
 * @category Guards
 * @since 2.0.0
 */
export const isSome = option.isSome;
/**
 * Performs pattern matching on an `Option` to handle both `Some` and `None`
 * cases.
 *
 * **Details**
 *
 * This function allows you to match against an `Option` and handle both
 * scenarios: when the `Option` is `None` (i.e., contains no value), and when
 * the `Option` is `Some` (i.e., contains a value). It executes one of the
 * provided functions based on the case:
 *
 * - If the `Option` is `None`, the `onNone` function is executed and its result
 *   is returned.
 * - If the `Option` is `Some`, the `onSome` function is executed with the
 *   contained value, and its result is returned.
 *
 * This function provides a concise and functional way to handle optional values
 * without resorting to `if` or manual checks, making your code more declarative
 * and readable.
 *
 * **Example** (Pattern Matching with Option)
 *
 * ```ts
 * import { Option } from "effect"
 *
 * const foo = Option.some(1)
 *
 * const message = Option.match(foo, {
 *   onNone: () => "Option is empty",
 *   onSome: (value) => `Option has a value: ${value}`
 * })
 *
 * console.log(message)
 * // Output: "Option has a value: 1"
 * ```
 *
 * @category Pattern matching
 * @since 2.0.0
 */
export const match = /*#__PURE__*/dual(2, (self, {
  onNone,
  onSome
}) => isNone(self) ? onNone() : onSome(self.value));
/**
 * Converts an `Option`-returning function into a type guard.
 *
 * **Details**
 *
 * This function transforms a function that returns an `Option` into a type
 * guard, ensuring type safety when validating or narrowing types. The returned
 * type guard function checks whether the input satisfies the condition defined
 * in the original `Option`-returning function.
 *
 * If the original function returns `Option.some`, the type guard evaluates to
 * `true`, confirming the input is of the desired type. If the function returns
 * `Option.none`, the type guard evaluates to `false`.
 *
 * This utility is especially useful for validating types in union types,
 * filtering arrays, or ensuring safe handling of specific subtypes.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * type MyData = string | number
 *
 * const parseString = (data: MyData): Option.Option<string> =>
 *   typeof data === "string" ? Option.some(data) : Option.none()
 *
 * //      ┌─── (a: MyData) => a is string
 * //      ▼
 * const isString = Option.toRefinement(parseString)
 *
 * console.log(isString("a"))
 * // Output: true
 *
 * console.log(isString(1))
 * // Output: false
 * ```
 *
 * @category Conversions
 * @since 2.0.0
 */
export const toRefinement = f => a => isSome(f(a));
/**
 * Converts an `Iterable` into an `Option`, wrapping the first element if it
 * exists.
 *
 * **Details**
 *
 * This function takes an `Iterable` (e.g., an array, a generator, or any object
 * implementing the `Iterable` interface) and returns an `Option` based on its
 * content:
 *
 * - If the `Iterable` contains at least one element, the first element is
 *   wrapped in a `Some` and returned.
 * - If the `Iterable` is empty, `None` is returned, representing the absence of
 *   a value.
 *
 * This utility is useful for safely handling collections that might be empty,
 * ensuring you explicitly handle both cases where a value exists or doesn't.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * console.log(Option.fromIterable([1, 2, 3]))
 * // Output: { _id: 'Option', _tag: 'Some', value: 1 }
 *
 * console.log(Option.fromIterable([]))
 * // Output: { _id: 'Option', _tag: 'None' }
 * ```
 *
 * @category Constructors
 * @since 2.0.0
 */
export const fromIterable = collection => {
  for (const a of collection) {
    return some(a);
  }
  return none();
};
/**
 * Converts an `Either` into an `Option` by discarding the error and extracting
 * the right value.
 *
 * **Details**
 *
 * This function takes an `Either` and returns an `Option` based on its value:
 *
 * - If the `Either` is a `Right`, its value is wrapped in a `Some` and
 *   returned.
 * - If the `Either` is a `Left`, the error is discarded, and `None` is
 *   returned.
 *
 * This is particularly useful when you only care about the success case
 * (`Right`) of an `Either` and want to handle the result using `Option`. By
 * using this function, you can convert `Either` into a simpler structure for
 * cases where error handling is not required.
 *
 * @example
 * ```ts
 * import { Either, Option } from "effect"
 *
 * console.log(Option.getRight(Either.right("ok")))
 * // Output: { _id: 'Option', _tag: 'Some', value: 'ok' }
 *
 * console.log(Option.getRight(Either.left("err")))
 * // Output: { _id: 'Option', _tag: 'None' }
 * ```
 *
 * @see {@link getLeft} for the opposite operation.
 *
 * @category Conversions
 * @since 2.0.0
 */
export const getRight = either.getRight;
/**
 * Converts an `Either` into an `Option` by discarding the right value and
 * extracting the left value.
 *
 * **Details**
 *
 * This function transforms an `Either` into an `Option` as follows:
 *
 * - If the `Either` is a `Left`, its value is wrapped in a `Some` and returned.
 * - If the `Either` is a `Right`, the value is discarded, and `None` is
 *   returned.
 *
 * This utility is useful when you only care about the error case (`Left`) of an
 * `Either` and want to handle it as an `Option`. By discarding the right value,
 * it simplifies error-focused workflows.
 *
 * @example
 * ```ts
 * import { Either, Option } from "effect"
 *
 * console.log(Option.getLeft(Either.right("ok")))
 * // Output: { _id: 'Option', _tag: 'None' }
 *
 * console.log(Option.getLeft(Either.left("err")))
 * // Output: { _id: 'Option', _tag: 'Some', value: 'err' }
 * ```
 *
 * @see {@link getRight} for the opposite operation.
 *
 * @category Conversions
 * @since 2.0.0
 */
export const getLeft = either.getLeft;
/**
 * Returns the value contained in the `Option` if it is `Some`, otherwise
 * evaluates and returns the result of `onNone`.
 *
 * **Details**
 *
 * This function allows you to provide a fallback value or computation for when
 * an `Option` is `None`. If the `Option` contains a value (`Some`), that value
 * is returned. If it is empty (`None`), the `onNone` function is executed, and
 * its result is returned instead.
 *
 * This utility is helpful for safely handling `Option` values by ensuring you
 * always receive a meaningful result, whether or not the `Option` contains a
 * value. It is particularly useful for providing default values or alternative
 * logic when working with optional values.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * console.log(Option.some(1).pipe(Option.getOrElse(() => 0)))
 * // Output: 1
 *
 * console.log(Option.none().pipe(Option.getOrElse(() => 0)))
 * // Output: 0
 * ```
 *
 * @see {@link getOrNull} for a version that returns `null` instead of executing a function.
 * @see {@link getOrUndefined} for a version that returns `undefined` instead of executing a function.
 *
 * @category Getters
 * @since 2.0.0
 */
export const getOrElse = /*#__PURE__*/dual(2, (self, onNone) => isNone(self) ? onNone() : self.value);
/**
 * Returns the provided `Option` `that` if the current `Option` (`self`) is
 * `None`; otherwise, it returns `self`.
 *
 * **Details**
 *
 * This function provides a fallback mechanism for `Option` values. If the
 * current `Option` is `None` (i.e., it contains no value), the `that` function
 * is evaluated, and its resulting `Option` is returned. If the current `Option`
 * is `Some` (i.e., it contains a value), the original `Option` is returned
 * unchanged.
 *
 * This is particularly useful for chaining fallback values or computations,
 * allowing you to provide alternative `Option` values when the first one is
 * empty.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * console.log(Option.none().pipe(Option.orElse(() => Option.none())))
 * // Output: { _id: 'Option', _tag: 'None' }
 *
 * console.log(Option.some("a").pipe(Option.orElse(() => Option.none())))
 * // Output: { _id: 'Option', _tag: 'Some', value: 'a' }
 *
 * console.log(Option.none().pipe(Option.orElse(() => Option.some("b"))))
 * // Output: { _id: 'Option', _tag: 'Some', value: 'b' }
 *
 * console.log(Option.some("a").pipe(Option.orElse(() => Option.some("b"))))
 * // Output: { _id: 'Option', _tag: 'Some', value: 'a' }
 * ```
 *
 * @category Error handling
 * @since 2.0.0
 */
export const orElse = /*#__PURE__*/dual(2, (self, that) => isNone(self) ? that() : self);
/**
 * Returns the provided default value wrapped in `Some` if the current `Option`
 * (`self`) is `None`; otherwise, returns `self`.
 *
 * **Details**
 *
 * This function provides a way to supply a default value for cases where an
 * `Option` is `None`. If the current `Option` is empty (`None`), the `onNone`
 * function is executed to compute the default value, which is then wrapped in a
 * `Some`. If the current `Option` contains a value (`Some`), it is returned as
 * is.
 *
 * This is particularly useful for handling optional values where a fallback
 * default needs to be provided explicitly in case of absence.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * console.log(Option.none().pipe(Option.orElseSome(() => "b")))
 * // Output: { _id: 'Option', _tag: 'Some', value: 'b' }
 *
 * console.log(Option.some("a").pipe(Option.orElseSome(() => "b")))
 * // Output: { _id: 'Option', _tag: 'Some', value: 'a' }
 * ```
 *
 * @category Error handling
 * @since 2.0.0
 */
export const orElseSome = /*#__PURE__*/dual(2, (self, onNone) => isNone(self) ? some(onNone()) : self);
/**
 * Similar to {@link orElse}, but returns an `Either` wrapped in an `Option` to
 * indicate the source of the value.
 *
 * **Details**
 *
 * This function allows you to provide a fallback `Option` in case the current
 * `Option` (`self`) is `None`. However, unlike `orElse`, it returns the value
 * wrapped in an `Either` object, providing additional information about where
 * the value came from:
 *
 * - If the value is from the fallback `Option` (`that`), it is wrapped in an
 *   `Either.right`.
 * - If the value is from the original `Option` (`self`), it is wrapped in an
 *   `Either.left`.
 *
 * This is especially useful when you need to differentiate between values
 * originating from the primary `Option` and those coming from the fallback,
 * while still maintaining the `Option`-style handling.
 *
 * @category Error handling
 * @since 2.0.0
 */
export const orElseEither = /*#__PURE__*/dual(2, (self, that) => isNone(self) ? map(that(), either.right) : map(self, either.left));
/**
 * Returns the first `Some` value found in an `Iterable` collection of
 * `Option`s, or `None` if no `Some` is found.
 *
 * **Details**
 *
 * This function iterates over a collection of `Option` values and returns the
 * first `Some` it encounters. If the collection contains only `None` values,
 * the result will also be `None`. This utility is useful for efficiently
 * finding the first valid value in a sequence of potentially empty or invalid
 * options.
 *
 * The iteration stops as soon as a `Some` is found, making this function
 * efficient for large collections.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * console.log(Option.firstSomeOf([
 *   Option.none(),
 *   Option.some(1),
 *   Option.some(2)
 * ]))
 * // Output: { _id: 'Option', _tag: 'Some', value: 1 }
 * ```
 *
 * @category Error handling
 * @since 2.0.0
 */
export const firstSomeOf = collection => {
  let out = none();
  for (out of collection) {
    if (isSome(out)) {
      return out;
    }
  }
  return out;
};
/**
 * Converts a nullable value into an `Option`. Returns `None` if the value is
 * `null` or `undefined`, otherwise wraps the value in a `Some`.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * console.log(Option.fromNullable(undefined))
 * // Output: { _id: 'Option', _tag: 'None' }
 *
 * console.log(Option.fromNullable(null))
 * // Output: { _id: 'Option', _tag: 'None' }
 *
 * console.log(Option.fromNullable(1))
 * // Output: { _id: 'Option', _tag: 'Some', value: 1 }
 * ```
 *
 * @category Conversions
 * @since 2.0.0
 */
export const fromNullable = nullableValue => nullableValue == null ? none() : some(nullableValue);
/**
 * Lifts a function that returns `null` or `undefined` into the `Option`
 * context.
 *
 * **Details**
 *
 * This function takes a function `f` that might return `null` or `undefined`
 * and transforms it into a function that returns an `Option`. The resulting
 * function will return:
 * - `Some` if the original function produces a non-null, non-undefined value.
 * - `None` if the original function produces `null` or `undefined`.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * const parse = (s: string): number | undefined => {
 *   const n = parseFloat(s)
 *   return isNaN(n) ? undefined : n
 * }
 *
 * const parseOption = Option.liftNullable(parse)
 *
 * console.log(parseOption("1"))
 * // Output: { _id: 'Option', _tag: 'Some', value: 1 }
 *
 * console.log(parseOption("not a number"))
 * // Output: { _id: 'Option', _tag: 'None' }
 * ```
 *
 * @category Conversions
 * @since 2.0.0
 */
export const liftNullable = f => (...a) => fromNullable(f(...a));
/**
 * Returns the value contained in the `Option` if it is `Some`; otherwise,
 * returns `null`.
 *
 * **Details**
 *
 * This function provides a way to extract the value of an `Option` while
 * falling back to `null` if the `Option` is `None`.
 *
 * It is particularly useful in scenarios where `null` is an acceptable
 * placeholder for the absence of a value, such as when interacting with APIs or
 * systems that use `null` as a default for missing values.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * console.log(Option.getOrNull(Option.some(1)))
 * // Output: 1
 *
 * console.log(Option.getOrNull(Option.none()))
 * // Output: null
 * ```
 *
 * @category Getters
 * @since 2.0.0
 */
export const getOrNull = /*#__PURE__*/getOrElse(constNull);
/**
 * Returns the value contained in the `Option` if it is `Some`; otherwise,
 * returns `undefined`.
 *
 * **Details**
 *
 * This function provides a way to extract the value of an `Option` while
 * falling back to `undefined` if the `Option` is `None`.
 *
 * It is particularly useful in scenarios where `undefined` is an acceptable
 * placeholder for the absence of a value, such as when interacting with APIs or
 * systems that use `undefined` as a default for missing values.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * console.log(Option.getOrUndefined(Option.some(1)))
 * // Output: 1
 *
 * console.log(Option.getOrUndefined(Option.none()))
 * // Output: undefined
 * ```
 *
 * @category Getters
 * @since 2.0.0
 */
export const getOrUndefined = /*#__PURE__*/getOrElse(constUndefined);
/**
 * Lifts a function that throws exceptions into a function that returns an
 * `Option`.
 *
 * **Details**
 *
 * This utility function takes a function `f` that might throw an exception and
 * transforms it into a safer function that returns an `Option`. If the original
 * function executes successfully, the result is wrapped in a `Some`. If an
 * exception is thrown, the result is `None`, allowing the developer to handle
 * errors in a functional, type-safe way.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * const parse = Option.liftThrowable(JSON.parse)
 *
 * console.log(parse("1"))
 * // Output: { _id: 'Option', _tag: 'Some', value: 1 }
 *
 * console.log(parse(""))
 * // Output: { _id: 'Option', _tag: 'None' }
 * ```
 *
 * @category Conversions
 * @since 2.0.0
 */
export const liftThrowable = f => (...a) => {
  try {
    return some(f(...a));
  } catch {
    return none();
  }
};
/**
 * Extracts the value of an `Option` or throws an error if the `Option` is
 * `None`, using a custom error factory.
 *
 * **Details**
 *
 * This function allows you to extract the value of an `Option` when it is
 * `Some`. If the `Option` is `None`, it throws an error generated by the
 * provided `onNone` function. This utility is particularly useful when you need
 * a fail-fast behavior for empty `Option` values and want to provide a custom
 * error message or object.
 *
 * @example
 * ```ts
 * import * as assert from "node:assert"
 * import { Option } from "effect"
 *
 * assert.deepStrictEqual(
 *   Option.getOrThrowWith(Option.some(1), () => new Error('Unexpected None')),
 *   1
 * )
 * assert.throws(() => Option.getOrThrowWith(Option.none(), () => new Error('Unexpected None')))
 * ```
 *
 * @see {@link getOrThrow} for a version that throws a default error.
 *
 * @category Conversions
 * @since 2.0.0
 */
export const getOrThrowWith = /*#__PURE__*/dual(2, (self, onNone) => {
  if (isSome(self)) {
    return self.value;
  }
  throw onNone();
});
/**
 * Extracts the value of an `Option` or throws a default error if the `Option`
 * is `None`.
 *
 * **Details**
 *
 * This function extracts the value from an `Option` if it is `Some`. If the
 * `Option` is `None`, it throws a default error. It is useful for fail-fast
 * scenarios where the absence of a value is treated as an exceptional case and
 * a default error is sufficient.
 *
 * @example
 * ```ts
 * import * as assert from "node:assert"
 * import { Option } from "effect"
 *
 * assert.deepStrictEqual(Option.getOrThrow(Option.some(1)), 1)
 * assert.throws(() => Option.getOrThrow(Option.none()))
 * ```
 *
 * @see {@link getOrThrowWith} for a version that allows you to provide a custom error.
 *
 * @category Conversions
 * @since 2.0.0
 */
export const getOrThrow = /*#__PURE__*/getOrThrowWith(() => new Error("getOrThrow called on a None"));
/**
 * Transforms the value inside a `Some` to a new value using the provided
 * function, while leaving `None` unchanged.
 *
 * **Details**
 *
 * This function applies a mapping function `f` to the value inside an `Option`
 * if it is a `Some`. If the `Option` is `None`, it remains unchanged. The
 * result is a new `Option` with the transformed value (if it was a `Some`) or
 * still `None`.
 *
 * This utility is particularly useful for chaining transformations in a
 * functional way without needing to manually handle `None` cases.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * // Mapping over a `Some`
 * const someValue = Option.some(2)
 *
 * console.log(Option.map(someValue, (n) => n * 2))
 * // Output: { _id: 'Option', _tag: 'Some', value: 4 }
 *
 * // Mapping over a `None`
 * const noneValue = Option.none<number>()
 *
 * console.log(Option.map(noneValue, (n) => n * 2))
 * // Output: { _id: 'Option', _tag: 'None' }
 * ```
 *
 * @category Mapping
 * @since 2.0.0
 */
export const map = /*#__PURE__*/dual(2, (self, f) => isNone(self) ? none() : some(f(self.value)));
/**
 * Replaces the value inside a `Some` with the specified constant value, leaving
 * `None` unchanged.
 *
 * **Details**
 *
 * This function transforms an `Option` by replacing the value inside a `Some`
 * with the given constant value `b`. If the `Option` is `None`, it remains
 * unchanged.
 *
 * This is useful when you want to preserve the presence of a value (`Some`) but
 * replace its content with a fixed value.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * // Replacing the value of a `Some`
 * const someValue = Option.some(42)
 *
 * console.log(Option.as(someValue, "new value"))
 * // Output: { _id: 'Option', _tag: 'Some', value: 'new value' }
 *
 * // Replacing a `None` (no effect)
 * const noneValue = Option.none<number>()
 *
 * console.log(Option.as(noneValue, "new value"))
 * // Output: { _id: 'Option', _tag: 'None' }
 * ```
 *
 * @category Mapping
 * @since 2.0.0
 */
export const as = /*#__PURE__*/dual(2, (self, b) => map(self, () => b));
/**
 * Replaces the value inside a `Some` with the constant value `void`, leaving
 * `None` unchanged.
 *
 * **Details**
 *
 * This function transforms an `Option` by replacing the value inside a `Some`
 * with `void`. If the `Option` is `None`, it remains unchanged.
 *
 * This is particularly useful in scenarios where the presence or absence of a
 * value is significant, but the actual content of the value is irrelevant.
 *
 * @category Mapping
 * @since 2.0.0
 */
export const asVoid = /*#__PURE__*/as(undefined);
const void_ = /*#__PURE__*/some(undefined);
export {
/**
 * @since 2.0.0
 */
void_ as void };
/**
 * Applies a function to the value of a `Some` and flattens the resulting
 * `Option`. If the input is `None`, it remains `None`.
 *
 * **Details**
 *
 * This function allows you to chain computations that return `Option` values.
 * If the input `Option` is `Some`, the provided function `f` is applied to the
 * contained value, and the resulting `Option` is returned. If the input is
 * `None`, the function is not applied, and the result remains `None`.
 *
 * This utility is particularly useful for sequencing operations that may fail
 * or produce optional results, enabling clean and concise workflows for
 * handling such cases.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * interface Address {
 *   readonly city: string
 *   readonly street: Option.Option<string>
 * }
 *
 * interface User {
 *   readonly id: number
 *   readonly username: string
 *   readonly email: Option.Option<string>
 *   readonly address: Option.Option<Address>
 * }
 *
 * const user: User = {
 *   id: 1,
 *   username: "john_doe",
 *   email: Option.some("john.doe@example.com"),
 *   address: Option.some({
 *     city: "New York",
 *     street: Option.some("123 Main St")
 *   })
 * }
 *
 * // Use flatMap to extract the street value
 * const street = user.address.pipe(
 *   Option.flatMap((address) => address.street)
 * )
 *
 * console.log(street)
 * // Output: { _id: 'Option', _tag: 'Some', value: '123 Main St' }
 * ```
 *
 * @category Sequencing
 * @since 2.0.0
 */
export const flatMap = /*#__PURE__*/dual(2, (self, f) => isNone(self) ? none() : f(self.value));
/**
 * Chains two `Option`s together. The second `Option` can either be a static
 * value or depend on the result of the first `Option`.
 *
 * **Details**
 *
 * This function enables sequencing of two `Option` computations. If the first
 * `Option` is `Some`, the second `Option` is evaluated. The second `Option` can
 * either:
 *
 * - Be a static `Option` value.
 * - Be a function that produces an `Option`, optionally based on the value of
 *   the first `Option`.
 *
 * If the first `Option` is `None`, the function skips the evaluation of the
 * second `Option` and directly returns `None`.
 *
 * @category Sequencing
 * @since 2.0.0
 */
export const andThen = /*#__PURE__*/dual(2, (self, f) => flatMap(self, a => {
  const b = isFunction(f) ? f(a) : f;
  return isOption(b) ? b : some(b);
}));
/**
 * Combines `flatMap` and `fromNullable`, transforming the value inside a `Some`
 * using a function that may return `null` or `undefined`.
 *
 * **Details**
 *
 * This function applies a transformation function `f` to the value inside a
 * `Some`. The function `f` may return a value, `null`, or `undefined`. If `f`
 * returns a value, it is wrapped in a `Some`. If `f` returns `null` or
 * `undefined`, the result is `None`. If the input `Option` is `None`, the
 * function is not applied, and `None` is returned.
 *
 * This utility is particularly useful when working with deeply nested optional
 * values or chaining computations that may result in `null` or `undefined` at
 * some point.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * interface Employee {
 *   company?: {
 *     address?: {
 *       street?: {
 *         name?: string
 *       }
 *     }
 *   }
 * }
 *
 * const employee1: Employee = { company: { address: { street: { name: "high street" } } } }
 *
 * // Extracting a deeply nested property
 * console.log(
 *   Option.some(employee1)
 *     .pipe(Option.flatMapNullable((employee) => employee.company?.address?.street?.name))
 * )
 * // Output: { _id: 'Option', _tag: 'Some', value: 'high street' }
 *
 * const employee2: Employee = { company: { address: { street: {} } } }
 *
 * // Property does not exist
 * console.log(
 *   Option.some(employee2)
 *     .pipe(Option.flatMapNullable((employee) => employee.company?.address?.street?.name))
 * )
 * // Output: { _id: 'Option', _tag: 'None' }
 * ```
 *
 * @category Sequencing
 * @since 2.0.0
 */
export const flatMapNullable = /*#__PURE__*/dual(2, (self, f) => isNone(self) ? none() : fromNullable(f(self.value)));
/**
 * Flattens an `Option` of `Option` into a single `Option`.
 *
 * **Details**
 *
 * This function takes an `Option` that wraps another `Option` and flattens it
 * into a single `Option`. If the outer `Option` is `Some`, the function
 * extracts the inner `Option`. If the outer `Option` is `None`, the result
 * remains `None`.
 *
 * This is useful for simplifying nested `Option` structures that may arise
 * during functional operations.
 *
 * @category Sequencing
 * @since 2.0.0
 */
export const flatten = /*#__PURE__*/flatMap(identity);
/**
 * Combines two `Option`s, keeping the value from the second `Option` if both
 * are `Some`.
 *
 * **Details**
 *
 * This function takes two `Option`s and returns the second one if the first is
 * `Some`. If the first `Option` is `None`, the result will also be `None`,
 * regardless of the second `Option`. It effectively "zips" the two `Option`s
 * while discarding the value from the first `Option`.
 *
 * This is particularly useful when sequencing computations where the result of
 * the first computation is not needed, and you only care about the result of
 * the second computation.
 *
 * @category Zipping
 * @since 2.0.0
 */
export const zipRight = /*#__PURE__*/dual(2, (self, that) => flatMap(self, () => that));
/**
 * Combines two `Option`s, keeping the value from the first `Option` if both are
 * `Some`.
 *
 * **Details**
 *
 * This function takes two `Option`s and returns the first one if it is `Some`.
 * If either the first `Option` or the second `Option` is `None`, the result
 * will be `None`. This operation "zips" the two `Option`s while discarding the
 * value from the second `Option`.
 *
 * This is useful when sequencing computations where the second `Option`
 * represents a dependency or condition that must hold, but its value is
 * irrelevant.
 *
 * @category Zipping
 * @since 2.0.0
 */
export const zipLeft = /*#__PURE__*/dual(2, (self, that) => tap(self, () => that));
/**
 * Composes two functions that return `Option` values, creating a new function
 * that chains them together.
 *
 * **Details**
 *
 * This function allows you to compose two computations, each represented by a
 * function that returns an `Option`. The result of the first function is passed
 * to the second function if it is `Some`. If the first function returns `None`,
 * the composed function short-circuits and returns `None` without invoking the
 * second function.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * const parse = (s: string): Option.Option<number> => isNaN(Number(s)) ? Option.none() : Option.some(Number(s))
 *
 * const double = (n: number): Option.Option<number> => n > 0 ? Option.some(n * 2) : Option.none()
 *
 * const parseAndDouble = Option.composeK(parse, double)
 *
 * console.log(parseAndDouble("42"))
 * // Output: { _id: 'Option', _tag: 'Some', value: 84 }
 *
 * console.log(parseAndDouble("not a number"))
 * // Output: { _id: 'Option', _tag: 'None' }
 * ```
 *
 * @category Sequencing
 * @since 2.0.0
 */
export const composeK = /*#__PURE__*/dual(2, (afb, bfc) => a => flatMap(afb(a), bfc));
/**
 * Applies the provided function `f` to the value of the `Option` if it is
 * `Some` and returns the original `Option`, unless `f` returns `None`, in which
 * case it returns `None`.
 *
 * **Details**
 *
 * This function allows you to perform additional computations on the value of
 * an `Option` without modifying its original value. If the `Option` is `Some`,
 * the provided function `f` is executed with the value, and its result
 * determines whether the original `Option` is returned (`Some`) or the result
 * is `None` if `f` returns `None`. If the input `Option` is `None`, the
 * function is not executed, and `None` is returned.
 *
 * This is particularly useful for applying side conditions or performing
 * validation checks while retaining the original `Option`'s value.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * const getInteger = (n: number) => Number.isInteger(n) ? Option.some(n) : Option.none()
 *
 * console.log(Option.tap(Option.none(), getInteger))
 * // Output: { _id: 'Option', _tag: 'None' }
 *
 * console.log(Option.tap(Option.some(1), getInteger))
 * // Output: { _id: 'Option', _tag: 'Some', value: 1 }
 *
 * console.log(Option.tap(Option.some(1.14), getInteger))
 * // Output: { _id: 'Option', _tag: 'None' }
 * ```
 *
 * @category Sequencing
 * @since 2.0.0
 */
export const tap = /*#__PURE__*/dual(2, (self, f) => flatMap(self, a => map(f(a), () => a)));
/**
 * Combines two `Option` values into a single `Option` containing a tuple of
 * their values if both are `Some`.
 *
 * **Details**
 *
 * This function takes two `Option`s and combines their values into a tuple `[A,
 * B]` if both are `Some`. If either of the `Option`s is `None`, the result is
 * `None`. This is particularly useful for combining multiple `Option` values
 * into a single one, ensuring both contain valid values.
 *
 * @category Combining
 * @since 2.0.0
 */
export const product = (self, that) => isSome(self) && isSome(that) ? some([self.value, that.value]) : none();
/**
 * Combines an `Option` with a collection of `Option`s into a single `Option`
 * containing a tuple of their values if all are `Some`.
 *
 * **Details**
 *
 * This function takes a primary `Option` and a collection of `Option`s and
 * combines their values into a tuple `[A, ...Array<A>]` if all are `Some`. If
 * the primary `Option` or any `Option` in the collection is `None`, the result
 * is `None`.
 *
 * @category Combining
 * @since 2.0.0
 */
export const productMany = (self, collection) => {
  if (isNone(self)) {
    return none();
  }
  const out = [self.value];
  for (const o of collection) {
    if (isNone(o)) {
      return none();
    }
    out.push(o.value);
  }
  return some(out);
};
/**
 * Combines a structure of `Option`s into a single `Option` containing the
 * values with the same structure.
 *
 * **Details**
 *
 * This function takes a structure of `Option`s (a tuple, struct, or iterable)
 * and produces a single `Option` that contains the values from the input
 * structure if all `Option`s are `Some`. If any `Option` in the input is
 * `None`, the result is `None`. The structure of the input is preserved in the
 * output.
 *
 * - If the input is a tuple (e.g., an array), the result will be an `Option`
 *   containing a tuple with the same length.
 * - If the input is a struct (e.g., an object), the result will be an `Option`
 *   containing a struct with the same keys.
 * - If the input is an iterable, the result will be an `Option` containing an
 *   array.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * const maybeName: Option.Option<string> = Option.some("John")
 * const maybeAge: Option.Option<number> = Option.some(25)
 *
 * //      ┌─── Option<[string, number]>
 * //      ▼
 * const tuple = Option.all([maybeName, maybeAge])
 * console.log(tuple)
 * // Output:
 * // { _id: 'Option', _tag: 'Some', value: [ 'John', 25 ] }
 *
 * //      ┌─── Option<{ name: string; age: number; }>
 * //      ▼
 * const struct = Option.all({ name: maybeName, age: maybeAge })
 * console.log(struct)
 * // Output:
 * // { _id: 'Option', _tag: 'Some', value: { name: 'John', age: 25 } }
 * ```
 *
 * @category Combining
 * @since 2.0.0
 */
// @ts-expect-error
export const all = input => {
  if (Symbol.iterator in input) {
    const out = [];
    for (const o of input) {
      if (isNone(o)) {
        return none();
      }
      out.push(o.value);
    }
    return some(out);
  }
  const out = {};
  for (const key of Object.keys(input)) {
    const o = input[key];
    if (isNone(o)) {
      return none();
    }
    out[key] = o.value;
  }
  return some(out);
};
/**
 * Combines two `Option` values into a new `Option` by applying a provided
 * function to their values.
 *
 * **Details**
 *
 * This function takes two `Option` values (`self` and `that`) and a combining
 * function `f`. If both `Option` values are `Some`, the function `f` is applied
 * to their values, and the result is wrapped in a new `Some`. If either
 * `Option` is `None`, the result is `None`.
 *
 * This utility is useful for combining two optional computations into a single
 * result while maintaining type safety and avoiding explicit checks for `None`.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * const maybeName: Option.Option<string> = Option.some("John")
 * const maybeAge: Option.Option<number> = Option.some(25)
 *
 * // Combine the name and age into a person object
 * const person = Option.zipWith(maybeName, maybeAge, (name, age) => ({
 *   name: name.toUpperCase(),
 *   age
 * }))
 *
 * console.log(person)
 * // Output:
 * // { _id: 'Option', _tag: 'Some', value: { name: 'JOHN', age: 25 } }
 * ```
 *
 * @category Zipping
 * @since 2.0.0
 */
export const zipWith = /*#__PURE__*/dual(3, (self, that, f) => map(product(self, that), ([a, b]) => f(a, b)));
/**
 * Applies a function inside a `Some` to a value inside another `Some`,
 * combining them into a new `Option`.
 *
 * **Details**
 *
 * This function allows you to apply a function wrapped in an `Option` (`self`)
 * to a value wrapped in another `Option` (`that`). If both `Option`s are
 * `Some`, the function is applied to the value, and the result is wrapped in a
 * new `Some`. If either `Option` is `None`, the result is `None`.
 *
 * @category Combining
 * @since 2.0.0
 */
export const ap = /*#__PURE__*/dual(2, (self, that) => zipWith(self, that, (f, a) => f(a)));
/**
 * Reduces an `Iterable` of `Option<A>` to a single value of type `B`, ignoring
 * elements that are `None`.
 *
 * **Details**
 *
 * This function takes an initial value of type `B` and a reducing function `f`
 * that combines the accumulator with values of type `A`. It processes an
 * iterable of `Option<A>`, applying `f` only to the `Some` values while
 * ignoring the `None` values. The result is a single value of type `B`.
 *
 * This utility is particularly useful for aggregating values from an iterable
 * of `Option`s while skipping the absent (`None`) values.
 *
 * @example
 * ```ts
 * import { Option, pipe } from "effect"
 *
 * const iterable = [Option.some(1), Option.none(), Option.some(2), Option.none()]
 *
 * console.log(pipe(iterable, Option.reduceCompact(0, (b, a) => b + a)))
 * // Output: 3
 * ```
 *
 * @category Reducing
 * @since 2.0.0
 */
export const reduceCompact = /*#__PURE__*/dual(3, (self, b, f) => {
  let out = b;
  for (const oa of self) {
    if (isSome(oa)) {
      out = f(out, oa.value);
    }
  }
  return out;
});
/**
 * Converts an `Option` into an `Array`.
 * If the input is `None`, an empty array is returned.
 * If the input is `Some`, its value is wrapped in a single-element array.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * console.log(Option.toArray(Option.some(1)))
 * // Output: [1]
 *
 * console.log(Option.toArray(Option.none()))
 * // Output: []
 * ```
 *
 * @category Conversions
 * @since 2.0.0
 */
export const toArray = self => isNone(self) ? [] : [self.value];
/**
 * Splits an `Option` into two `Option`s based on the result of a mapping
 * function that produces an `Either`.
 *
 * **Details**
 *
 * This function takes an `Option` and a mapping function `f` that converts its
 * value into an `Either`. It returns a tuple of two `Option`s:
 *
 * - The first `Option` (`left`) contains the value from the `Left` side of the
 *   `Either` if it exists, otherwise `None`.
 * - The second `Option` (`right`) contains the value from the `Right` side of
 *   the `Either` if it exists, otherwise `None`.
 *
 * If the input `Option` is `None`, both returned `Option`s are `None`.
 *
 * This utility is useful for filtering and categorizing the contents of an
 * `Option` based on a bifurcating computation.
 *
 * @category Filtering
 * @since 2.0.0
 */
export const partitionMap = /*#__PURE__*/dual(2, (self, f) => {
  if (isNone(self)) {
    return [none(), none()];
  }
  const e = f(self.value);
  return either.isLeft(e) ? [some(e.left), none()] : [none(), some(e.right)];
});
// TODO(4.0): remove?
/**
 * Alias of {@link flatMap}.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * // Transform and filter numbers
 * const transformEven = (n: Option.Option<number>): Option.Option<string> =>
 *   Option.filterMap(n, (n) => (n % 2 === 0 ? Option.some(`Even: ${n}`) : Option.none()))
 *
 * console.log(transformEven(Option.none()))
 * // Output: { _id: 'Option', _tag: 'None' }
 *
 * console.log(transformEven(Option.some(1)))
 * // Output: { _id: 'Option', _tag: 'None' }
 *
 * console.log(transformEven(Option.some(2)))
 * // Output: { _id: 'Option', _tag: 'Some', value: 'Even: 2' }
 * ```
 *
 * @category Filtering
 * @since 2.0.0
 */
export const filterMap = flatMap;
/**
 * Filters an `Option` using a predicate. If the predicate is not satisfied or the `Option` is `None` returns `None`.
 *
 * If you need to change the type of the `Option` in addition to filtering, see `filterMap`.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * const removeEmptyString = (input: Option.Option<string>) =>
 *   Option.filter(input, (value) => value !== "")
 *
 * console.log(removeEmptyString(Option.none()))
 * // Output: { _id: 'Option', _tag: 'None' }
 *
 * console.log(removeEmptyString(Option.some("")))
 * // Output: { _id: 'Option', _tag: 'None' }
 *
 * console.log(removeEmptyString(Option.some("a")))
 * // Output: { _id: 'Option', _tag: 'Some', value: 'a' }
 * ```
 *
 * @category Filtering
 * @since 2.0.0
 */
export const filter = /*#__PURE__*/dual(2, (self, predicate) => filterMap(self, b => predicate(b) ? option.some(b) : option.none));
/**
 * Creates an `Equivalence` instance for comparing `Option` values, using a
 * provided `Equivalence` for the inner type.
 *
 * **Details**
 *
 * This function takes an `Equivalence` instance for a specific type `A` and
 * produces an `Equivalence` instance for `Option<A>`. The resulting
 * `Equivalence` determines whether two `Option` values are equivalent:
 *
 * - Two `None`s are considered equivalent.
 * - A `Some` and a `None` are not equivalent.
 * - Two `Some` values are equivalent if their inner values are equivalent
 *   according to the provided `Equivalence`.
 *
 * **Example** (Comparing Optional Numbers for Equivalence)
 *
 * ```ts
 * import { Number, Option } from "effect"
 *
 * const isEquivalent = Option.getEquivalence(Number.Equivalence)
 *
 * console.log(isEquivalent(Option.none(), Option.none()))
 * // Output: true
 *
 * console.log(isEquivalent(Option.none(), Option.some(1)))
 * // Output: false
 *
 * console.log(isEquivalent(Option.some(1), Option.none()))
 * // Output: false
 *
 * console.log(isEquivalent(Option.some(1), Option.some(2)))
 * // Output: false
 *
 * console.log(isEquivalent(Option.some(1), Option.some(1)))
 * // Output: true
 * ```
 *
 * @category Equivalence
 * @since 2.0.0
 */
export const getEquivalence = isEquivalent => Equivalence.make((x, y) => isNone(x) ? isNone(y) : isNone(y) ? false : isEquivalent(x.value, y.value));
/**
 * Creates an `Order` instance for comparing `Option` values, using a provided
 * `Order` for the inner type.
 *
 * **Details**
 *
 * This function produces an `Order` instance for `Option<A>`, allowing `Option`
 * values to be compared:
 *
 * - `None` is always considered less than any `Some` value.
 * - If both are `Some`, their inner values are compared using the provided
 *   `Order` instance.
 *
 * @example
 * ```ts
 * import { Number, Option } from "effect"
 *
 * const order = Option.getOrder(Number.Order)
 *
 * console.log(order(Option.none(), Option.none()))
 * // Output: 0
 *
 * console.log(order(Option.none(), Option.some(1)))
 * // Output: -1
 *
 * console.log(order(Option.some(1), Option.none()))
 * // Output: 1
 *
 * console.log(order(Option.some(1), Option.some(2)))
 * // Output: -1
 *
 * console.log(order(Option.some(1), Option.some(1)))
 * // Output: 0
 * ```
 *
 * @category Sorting
 * @since 2.0.0
 */
export const getOrder = O => order.make((self, that) => isSome(self) ? isSome(that) ? O(self.value, that.value) : 1 : -1);
/**
 * Lifts a binary function to work with `Option` values, allowing the function
 * to operate on two `Option`s.
 *
 * **Details**
 *
 * This function takes a binary function `f` and returns a new function that
 * applies `f` to the values of two `Option`s (`self` and `that`). If both
 * `Option`s are `Some`, the binary function `f` is applied to their values, and
 * the result is wrapped in a new `Some`. If either `Option` is `None`, the
 * result is `None`.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * // A binary function to add two numbers
 * const add = (a: number, b: number): number => a + b
 *
 * // Lift the `add` function to work with `Option` values
 * const addOptions = Option.lift2(add)
 *
 * // Both `Option`s are `Some`
 * console.log(addOptions(Option.some(2), Option.some(3)))
 * // Output: { _id: 'Option', _tag: 'Some', value: 5 }
 *
 * // One `Option` is `None`
 * console.log(addOptions(Option.some(2), Option.none()))
 * // Output: { _id: 'Option', _tag: 'None' }
 * ```
 *
 * @category Lifting
 * @since 2.0.0
 */
export const lift2 = f => dual(2, (self, that) => zipWith(self, that, f));
/**
 * Lifts a `Predicate` or `Refinement` into the `Option` context, returning a
 * `Some` of the input value if the predicate is satisfied, or `None` otherwise.
 *
 * **Details**
 *
 * This function transforms a `Predicate` (or a more specific `Refinement`) into
 * a function that produces an `Option`. If the predicate evaluates to `true`,
 * the input value is wrapped in a `Some`. If the predicate evaluates to
 * `false`, the result is `None`.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * // Check if a number is positive
 * const isPositive = (n: number) => n > 0
 *
 * //      ┌─── (b: number) => Option<number>
 * //      ▼
 * const parsePositive = Option.liftPredicate(isPositive)
 *
 * console.log(parsePositive(1))
 * // Output: { _id: 'Option', _tag: 'Some', value: 1 }
 *
 * console.log(parsePositive(-1))
 * // OUtput: { _id: 'Option', _tag: 'None' }
 * ```
 *
 * @category Lifting
 * @since 2.0.0
 */
export const liftPredicate = /*#__PURE__*/dual(2, (b, predicate) => predicate(b) ? some(b) : none());
/**
 * Returns a function that checks if an `Option` contains a specified value,
 * using a provided equivalence function.
 *
 * **Details**
 *
 * This function allows you to check whether an `Option` contains a specific
 * value. It uses an equivalence function `isEquivalent` to compare the value
 * inside the `Option` to the provided value. If the `Option` is `Some` and the
 * equivalence function returns `true`, the result is `true`. If the `Option` is
 * `None` or the values are not equivalent, the result is `false`.
 *
 * @example
 * ```ts
 * import { Number, Option } from "effect"
 *
 * const contains = Option.containsWith(Number.Equivalence)
 *
 * console.log(Option.some(2).pipe(contains(2)))
 * // Output: true
 *
 * console.log(Option.some(1).pipe(contains(2)))
 * // Output: false
 *
 * console.log(Option.none().pipe(contains(2)))
 * // Output: false
 * ```
 *
 * @see {@link contains} for a version that uses the default `Equivalence`.
 *
 * @category Elements
 * @since 2.0.0
 */
export const containsWith = isEquivalent => dual(2, (self, a) => isNone(self) ? false : isEquivalent(self.value, a));
const _equivalence = /*#__PURE__*/Equal.equivalence();
/**
 * Returns a function that checks if an `Option` contains a specified value
 * using the default `Equivalence`.
 *
 * **Details**
 *
 * This function allows you to check whether an `Option` contains a specific
 * value. It uses the default `Equivalence` for equality comparison. If the
 * `Option` is `Some` and its value is equivalent to the provided value, the
 * result is `true`. If the `Option` is `None` or the values are not equivalent,
 * the result is `false`.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * console.log(Option.some(2).pipe(Option.contains(2)))
 * // Output: true
 *
 * console.log(Option.some(1).pipe(Option.contains(2)))
 * // Output: false
 *
 * console.log(Option.none().pipe(Option.contains(2)))
 * // Output: false
 * ```
 *
 * @see {@link containsWith} for a version that allows you to specify a custom equivalence function.
 *
 * @category Elements
 * @since 2.0.0
 */
export const contains = /*#__PURE__*/containsWith(_equivalence);
/**
 * Checks if a value in an `Option` satisfies a given predicate or refinement.
 *
 * **Details**
 *
 * This function allows you to check if a value inside a `Some` meets a
 * specified condition. If the `Option` is `None`, the result is `false`. If the
 * `Option` is `Some`, the provided predicate or refinement is applied to the
 * value:
 *
 * - If the condition is met, the result is `true`.
 * - If the condition is not met, the result is `false`.
 *
 * @example
 * ```ts
 * import { Option } from "effect"
 *
 * const isEven = (n: number) => n % 2 === 0
 *
 * console.log(Option.some(2).pipe(Option.exists(isEven)))
 * // Output: true
 *
 * console.log(Option.some(1).pipe(Option.exists(isEven)))
 * // Output: false
 *
 * console.log(Option.none().pipe(Option.exists(isEven)))
 * // Output: false
 * ```
 *
 * @category Elements
 * @since 2.0.0
 */
export const exists = /*#__PURE__*/dual(2, (self, refinement) => isNone(self) ? false : refinement(self.value));
// -------------------------------------------------------------------------------------
// do notation
// -------------------------------------------------------------------------------------
/**
 * The "do simulation" in Effect allows you to write code in a more declarative style, similar to the "do notation" in other programming languages. It provides a way to define variables and perform operations on them using functions like `bind` and `let`.
 *
 * Here's how the do simulation works:
 *
 * 1. Start the do simulation using the `Do` value
 * 2. Within the do simulation scope, you can use the `bind` function to define variables and bind them to `Option` values
 * 3. You can accumulate multiple `bind` statements to define multiple variables within the scope
 * 4. Inside the do simulation scope, you can also use the `let` function to define variables and bind them to simple values
 * 5. Regular `Option` functions like `map` and `filter` can still be used within the do simulation. These functions will receive the accumulated variables as arguments within the scope
 *
 * @example
 * ```ts
 * import * as assert from "node:assert"
 * import { Option, pipe } from "effect"
 *
 * const result = pipe(
 *   Option.Do,
 *   Option.bind("x", () => Option.some(2)),
 *   Option.bind("y", () => Option.some(3)),
 *   Option.let("sum", ({ x, y }) => x + y),
 *   Option.filter(({ x, y }) => x * y > 5)
 * )
 * assert.deepStrictEqual(result, Option.some({ x: 2, y: 3, sum: 5 }))
 * ```
 *
 * @see {@link Do}
 * @see {@link bind}
 * @see {@link let_ let}
 *
 * @category Do notation
 * @since 2.0.0
 */
export const bindTo = /*#__PURE__*/doNotation.bindTo(map);
const let_ = /*#__PURE__*/doNotation.let_(map);
export {
/**
 * The "do simulation" in Effect allows you to write code in a more declarative style, similar to the "do notation" in other programming languages. It provides a way to define variables and perform operations on them using functions like `bind` and `let`.
 *
 * Here's how the do simulation works:
 *
 * 1. Start the do simulation using the `Do` value
 * 2. Within the do simulation scope, you can use the `bind` function to define variables and bind them to `Option` values
 * 3. You can accumulate multiple `bind` statements to define multiple variables within the scope
 * 4. Inside the do simulation scope, you can also use the `let` function to define variables and bind them to simple values
 * 5. Regular `Option` functions like `map` and `filter` can still be used within the do simulation. These functions will receive the accumulated variables as arguments within the scope
 *
 * @example
 * ```ts
 * import * as assert from "node:assert"
 * import { Option, pipe } from "effect"
 *
 * const result = pipe(
 *   Option.Do,
 *   Option.bind("x", () => Option.some(2)),
 *   Option.bind("y", () => Option.some(3)),
 *   Option.let("sum", ({ x, y }) => x + y),
 *   Option.filter(({ x, y }) => x * y > 5)
 * )
 * assert.deepStrictEqual(result, Option.some({ x: 2, y: 3, sum: 5 }))
 * ```
 *
 * @see {@link Do}
 * @see {@link bind}
 * @see {@link bindTo}
 *
 * @category Do notation
 * @since 2.0.0
 */
let_ as let };
/**
 * The "do simulation" in Effect allows you to write code in a more declarative style, similar to the "do notation" in other programming languages. It provides a way to define variables and perform operations on them using functions like `bind` and `let`.
 *
 * Here's how the do simulation works:
 *
 * 1. Start the do simulation using the `Do` value
 * 2. Within the do simulation scope, you can use the `bind` function to define variables and bind them to `Option` values
 * 3. You can accumulate multiple `bind` statements to define multiple variables within the scope
 * 4. Inside the do simulation scope, you can also use the `let` function to define variables and bind them to simple values
 * 5. Regular `Option` functions like `map` and `filter` can still be used within the do simulation. These functions will receive the accumulated variables as arguments within the scope
 *
 * @example
 * ```ts
 * import * as assert from "node:assert"
 * import { Option, pipe } from "effect"
 *
 * const result = pipe(
 *   Option.Do,
 *   Option.bind("x", () => Option.some(2)),
 *   Option.bind("y", () => Option.some(3)),
 *   Option.let("sum", ({ x, y }) => x + y),
 *   Option.filter(({ x, y }) => x * y > 5)
 * )
 * assert.deepStrictEqual(result, Option.some({ x: 2, y: 3, sum: 5 }))
 * ```
 *
 * @see {@link Do}
 * @see {@link bindTo}
 * @see {@link let_ let}
 *
 * @category Do notation
 * @since 2.0.0
 */
export const bind = /*#__PURE__*/doNotation.bind(map, flatMap);
/**
 * The "do simulation" in Effect allows you to write code in a more declarative style, similar to the "do notation" in other programming languages. It provides a way to define variables and perform operations on them using functions like `bind` and `let`.
 *
 * Here's how the do simulation works:
 *
 * 1. Start the do simulation using the `Do` value
 * 2. Within the do simulation scope, you can use the `bind` function to define variables and bind them to `Option` values
 * 3. You can accumulate multiple `bind` statements to define multiple variables within the scope
 * 4. Inside the do simulation scope, you can also use the `let` function to define variables and bind them to simple values
 * 5. Regular `Option` functions like `map` and `filter` can still be used within the do simulation. These functions will receive the accumulated variables as arguments within the scope
 *
 * @example
 * ```ts
 * import * as assert from "node:assert"
 * import { Option, pipe } from "effect"
 *
 * const result = pipe(
 *   Option.Do,
 *   Option.bind("x", () => Option.some(2)),
 *   Option.bind("y", () => Option.some(3)),
 *   Option.let("sum", ({ x, y }) => x + y),
 *   Option.filter(({ x, y }) => x * y > 5)
 * )
 * assert.deepStrictEqual(result, Option.some({ x: 2, y: 3, sum: 5 }))
 * ```
 *
 * @see {@link bindTo}
 * @see {@link bind}
 * @see {@link let_ let}
 *
 * @category Do notation
 * @since 2.0.0
 */
export const Do = /*#__PURE__*/some({});
const adapter = /*#__PURE__*/Gen.adapter();
/**
 * Similar to `Effect.gen`, `Option.gen` provides a more readable,
 * generator-based syntax for working with `Option` values, making code that
 * involves `Option` easier to write and understand. This approach is similar to
 * using `async/await` but tailored for `Option`.
 *
 * **Example** (Using `Option.gen` to Create a Combined Value)
 *
 * ```ts
 * import { Option } from "effect"
 *
 * const maybeName: Option.Option<string> = Option.some("John")
 * const maybeAge: Option.Option<number> = Option.some(25)
 *
 * const person = Option.gen(function* () {
 *   const name = (yield* maybeName).toUpperCase()
 *   const age = yield* maybeAge
 *   return { name, age }
 * })
 *
 * console.log(person)
 * // Output:
 * // { _id: 'Option', _tag: 'Some', value: { name: 'JOHN', age: 25 } }
 * ```
 *
 * @category Generators
 * @since 2.0.0
 */
export const gen = (...args) => {
  const f = args.length === 1 ? args[0] : args[1].bind(args[0]);
  const iterator = f(adapter);
  let state = iterator.next();
  while (!state.done) {
    const current = Gen.isGenKind(state.value) ? state.value.value : Gen.yieldWrapGet(state.value);
    if (isNone(current)) {
      return current;
    }
    state = iterator.next(current.value);
  }
  return some(state.value);
};
/**
 * Merges two optional values, applying a function if both exist.
 * Unlike {@link zipWith}, this function returns `None` only if both inputs are `None`.
 *
 * @internal
 */
export const mergeWith = f => (o1, o2) => {
  if (isNone(o1)) {
    return o2;
  } else if (isNone(o2)) {
    return o1;
  }
  return some(f(o1.value, o2.value));
};
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