688 lines
21 KiB
JavaScript
688 lines
21 KiB
JavaScript
/**
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* @since 2.0.0
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*/
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import * as Equivalence from "./Equivalence.js";
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import { constNull, constUndefined, dual, identity } from "./Function.js";
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import * as doNotation from "./internal/doNotation.js";
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import * as either from "./internal/either.js";
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import * as option_ from "./internal/option.js";
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import { isFunction } from "./Predicate.js";
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import * as Gen from "./Utils.js";
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/**
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* @category symbols
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* @since 2.0.0
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*/
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export const TypeId = either.TypeId;
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/**
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* Constructs a new `Either` holding a `Right` value. This usually represents a successful value due to the right bias
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* of this structure.
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*
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* @category constructors
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* @since 2.0.0
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*/
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export const right = either.right;
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const void_ = /*#__PURE__*/right(void 0);
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export {
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/**
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* @category constructors
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* @since 3.13.0
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*/
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void_ as void };
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/**
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* Constructs a new `Either` holding a `Left` value. This usually represents a failure, due to the right-bias of this
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* structure.
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*
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* @category constructors
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* @since 2.0.0
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*/
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export const left = either.left;
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/**
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* Takes a lazy default and a nullable value, if the value is not nully (`null` or `undefined`), turn it into a `Right`, if the value is nully use
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* the provided default as a `Left`.
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*
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* @example
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* ```ts
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* import * as assert from "node:assert"
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* import { Either } from "effect"
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*
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* assert.deepStrictEqual(Either.fromNullable(1, () => 'fallback'), Either.right(1))
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* assert.deepStrictEqual(Either.fromNullable(null, () => 'fallback'), Either.left('fallback'))
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* ```
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*
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* @category constructors
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* @since 2.0.0
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*/
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export const fromNullable = /*#__PURE__*/dual(2, (self, onNullable) => self == null ? left(onNullable(self)) : right(self));
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/**
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* @example
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* ```ts
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* import * as assert from "node:assert"
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* import { Either, Option } from "effect"
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*
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* assert.deepStrictEqual(Either.fromOption(Option.some(1), () => 'error'), Either.right(1))
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* assert.deepStrictEqual(Either.fromOption(Option.none(), () => 'error'), Either.left('error'))
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* ```
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*
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* @category constructors
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* @since 2.0.0
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*/
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export const fromOption = either.fromOption;
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const try_ = evaluate => {
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if (isFunction(evaluate)) {
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try {
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return right(evaluate());
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} catch (e) {
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return left(e);
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}
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} else {
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try {
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return right(evaluate.try());
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} catch (e) {
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return left(evaluate.catch(e));
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}
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}
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};
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export {
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/**
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* Imports a synchronous side-effect into a pure `Either` value, translating any
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* thrown exceptions into typed failed eithers creating with `Either.left`.
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*
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* @category constructors
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* @since 2.0.0
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*/
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try_ as try };
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/**
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* Tests if a value is a `Either`.
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*
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* @example
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* ```ts
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* import * as assert from "node:assert"
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* import { Either } from "effect"
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*
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* assert.deepStrictEqual(Either.isEither(Either.right(1)), true)
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* assert.deepStrictEqual(Either.isEither(Either.left("a")), true)
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* assert.deepStrictEqual(Either.isEither({ right: 1 }), false)
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* ```
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*
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* @category guards
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* @since 2.0.0
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*/
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export const isEither = either.isEither;
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/**
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* Determine if a `Either` is a `Left`.
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*
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* @example
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* ```ts
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* import * as assert from "node:assert"
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* import { Either } from "effect"
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*
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* assert.deepStrictEqual(Either.isLeft(Either.right(1)), false)
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* assert.deepStrictEqual(Either.isLeft(Either.left("a")), true)
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* ```
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*
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* @category guards
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* @since 2.0.0
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*/
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export const isLeft = either.isLeft;
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/**
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* Determine if a `Either` is a `Right`.
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*
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* @example
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* ```ts
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* import * as assert from "node:assert"
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* import { Either } from "effect"
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*
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* assert.deepStrictEqual(Either.isRight(Either.right(1)), true)
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* assert.deepStrictEqual(Either.isRight(Either.left("a")), false)
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* ```
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*
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* @category guards
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* @since 2.0.0
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*/
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export const isRight = either.isRight;
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/**
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* Converts a `Either` to an `Option` discarding the `Left`.
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*
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* @example
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* ```ts
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* import * as assert from "node:assert"
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* import { Either, Option } from "effect"
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*
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* assert.deepStrictEqual(Either.getRight(Either.right('ok')), Option.some('ok'))
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* assert.deepStrictEqual(Either.getRight(Either.left('err')), Option.none())
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* ```
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*
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* @category getters
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* @since 2.0.0
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*/
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export const getRight = either.getRight;
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/**
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* Converts a `Either` to an `Option` discarding the value.
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*
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* @example
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* ```ts
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* import * as assert from "node:assert"
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* import { Either, Option } from "effect"
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*
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* assert.deepStrictEqual(Either.getLeft(Either.right('ok')), Option.none())
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* assert.deepStrictEqual(Either.getLeft(Either.left('err')), Option.some('err'))
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* ```
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*
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* @category getters
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* @since 2.0.0
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*/
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export const getLeft = either.getLeft;
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/**
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* @category equivalence
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* @since 2.0.0
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*/
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export const getEquivalence = ({
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left,
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right
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}) => Equivalence.make((x, y) => isLeft(x) ? isLeft(y) && left(x.left, y.left) : isRight(y) && right(x.right, y.right));
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/**
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* @category mapping
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* @since 2.0.0
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*/
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export const mapBoth = /*#__PURE__*/dual(2, (self, {
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onLeft,
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onRight
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}) => isLeft(self) ? left(onLeft(self.left)) : right(onRight(self.right)));
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/**
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* Maps the `Left` side of an `Either` value to a new `Either` value.
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*
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* @category mapping
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* @since 2.0.0
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*/
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export const mapLeft = /*#__PURE__*/dual(2, (self, f) => isLeft(self) ? left(f(self.left)) : right(self.right));
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/**
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* Maps the `Right` side of an `Either` value to a new `Either` value.
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*
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* @category mapping
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* @since 2.0.0
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*/
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export const map = /*#__PURE__*/dual(2, (self, f) => isRight(self) ? right(f(self.right)) : left(self.left));
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/**
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* Takes two functions and an `Either` value, if the value is a `Left` the inner value is applied to the `onLeft function,
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* if the value is a `Right` the inner value is applied to the `onRight` function.
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*
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* @example
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* ```ts
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* import * as assert from "node:assert"
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* import { pipe, Either } from "effect"
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*
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* const onLeft = (strings: ReadonlyArray<string>): string => `strings: ${strings.join(', ')}`
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*
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* const onRight = (value: number): string => `Ok: ${value}`
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*
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* assert.deepStrictEqual(pipe(Either.right(1), Either.match({ onLeft, onRight })), 'Ok: 1')
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* assert.deepStrictEqual(
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* pipe(Either.left(['string 1', 'string 2']), Either.match({ onLeft, onRight })),
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* 'strings: string 1, string 2'
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* )
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* ```
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*
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* @category pattern matching
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* @since 2.0.0
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*/
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export const match = /*#__PURE__*/dual(2, (self, {
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onLeft,
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onRight
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}) => isLeft(self) ? onLeft(self.left) : onRight(self.right));
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/**
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* Transforms a `Predicate` function into a `Right` of the input value if the predicate returns `true`
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* or `Left` of the result of the provided function if the predicate returns false
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*
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* @example
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* ```ts
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* import * as assert from "node:assert"
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* import { pipe, Either } from "effect"
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*
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* const isPositive = (n: number): boolean => n > 0
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* const isPositiveEither = Either.liftPredicate(isPositive, n => `${n} is not positive`)
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*
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* assert.deepStrictEqual(
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* isPositiveEither(1),
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* Either.right(1)
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* )
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* assert.deepStrictEqual(
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* isPositiveEither(0),
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* Either.left("0 is not positive")
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* )
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* ```
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*
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* @category lifting
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* @since 3.4.0
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*/
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export const liftPredicate = /*#__PURE__*/dual(3, (a, predicate, orLeftWith) => predicate(a) ? right(a) : left(orLeftWith(a)));
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/**
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* Filter the right value with the provided function.
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* If the predicate fails, set the left value with the result of the provided function.
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*
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* @example
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* ```ts
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* import * as assert from "node:assert"
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* import { pipe, Either } from "effect"
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*
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* const isPositive = (n: number): boolean => n > 0
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*
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* assert.deepStrictEqual(
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* pipe(
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* Either.right(1),
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* Either.filterOrLeft(isPositive, n => `${n} is not positive`)
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* ),
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* Either.right(1)
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* )
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* assert.deepStrictEqual(
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* pipe(
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* Either.right(0),
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* Either.filterOrLeft(isPositive, n => `${n} is not positive`)
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* ),
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* Either.left("0 is not positive")
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* )
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* ```
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*
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* @since 2.0.0
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* @category filtering & conditionals
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*/
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export const filterOrLeft = /*#__PURE__*/dual(3, (self, predicate, orLeftWith) => flatMap(self, r => predicate(r) ? right(r) : left(orLeftWith(r))));
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/**
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* @category getters
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* @since 2.0.0
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*/
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export const merge = /*#__PURE__*/match({
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onLeft: identity,
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onRight: identity
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});
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/**
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* Returns the wrapped value if it's a `Right` or a default value if is a `Left`.
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*
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* @example
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* ```ts
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* import * as assert from "node:assert"
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* import { Either } from "effect"
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*
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* assert.deepStrictEqual(Either.getOrElse(Either.right(1), (error) => error + "!"), 1)
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* assert.deepStrictEqual(Either.getOrElse(Either.left("not a number"), (error) => error + "!"), "not a number!")
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* ```
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*
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* @category getters
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* @since 2.0.0
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*/
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export const getOrElse = /*#__PURE__*/dual(2, (self, onLeft) => isLeft(self) ? onLeft(self.left) : self.right);
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/**
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* @example
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* ```ts
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* import * as assert from "node:assert"
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* import { Either } from "effect"
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*
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* assert.deepStrictEqual(Either.getOrNull(Either.right(1)), 1)
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* assert.deepStrictEqual(Either.getOrNull(Either.left("a")), null)
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* ```
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*
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* @category getters
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* @since 2.0.0
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*/
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export const getOrNull = /*#__PURE__*/getOrElse(constNull);
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/**
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* @example
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* ```ts
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* import * as assert from "node:assert"
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* import { Either } from "effect"
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*
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* assert.deepStrictEqual(Either.getOrUndefined(Either.right(1)), 1)
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* assert.deepStrictEqual(Either.getOrUndefined(Either.left("a")), undefined)
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* ```
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*
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* @category getters
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* @since 2.0.0
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*/
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export const getOrUndefined = /*#__PURE__*/getOrElse(constUndefined);
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/**
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* Extracts the value of an `Either` or throws if the `Either` is `Left`.
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*
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* If a default error is sufficient for your use case and you don't need to configure the thrown error, see {@link getOrThrow}.
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*
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* @example
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* ```ts
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* import * as assert from "node:assert"
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* import { Either } from "effect"
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*
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* assert.deepStrictEqual(
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* Either.getOrThrowWith(Either.right(1), () => new Error('Unexpected Left')),
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* 1
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* )
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* assert.throws(() => Either.getOrThrowWith(Either.left("error"), () => new Error('Unexpected Left')))
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* ```
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*
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* @category getters
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* @since 2.0.0
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*/
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export const getOrThrowWith = /*#__PURE__*/dual(2, (self, onLeft) => {
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if (isRight(self)) {
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return self.right;
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}
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throw onLeft(self.left);
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});
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// TODO(4.0): by default should throw `L` (i.e getOrThrowWith with the identity function)
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/**
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* Extracts the value of an `Either` or throws if the `Either` is `Left`.
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*
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* The thrown error is a default error. To configure the error thrown, see {@link getOrThrowWith}.
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*
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* @example
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* ```ts
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* import * as assert from "node:assert"
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* import { Either } from "effect"
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*
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* assert.deepStrictEqual(Either.getOrThrow(Either.right(1)), 1)
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* assert.throws(() => Either.getOrThrow(Either.left("error")))
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* ```
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*
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* @throws `Error("getOrThrow called on a Left")`
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*
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* @category getters
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* @since 2.0.0
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*/
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export const getOrThrow = /*#__PURE__*/getOrThrowWith(() => new Error("getOrThrow called on a Left"));
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/**
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* Returns `self` if it is a `Right` or `that` otherwise.
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*
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* @category error handling
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* @since 2.0.0
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*/
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export const orElse = /*#__PURE__*/dual(2, (self, that) => isLeft(self) ? that(self.left) : right(self.right));
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/**
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* @category sequencing
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* @since 2.0.0
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*/
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export const flatMap = /*#__PURE__*/dual(2, (self, f) => isLeft(self) ? left(self.left) : f(self.right));
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/**
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* Executes a sequence of two `Either`s. The second `Either` can be dependent on the result of the first `Either`.
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*
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* @category sequencing
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* @since 2.0.0
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*/
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export const andThen = /*#__PURE__*/dual(2, (self, f) => flatMap(self, a => {
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const b = isFunction(f) ? f(a) : f;
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return isEither(b) ? b : right(b);
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}));
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/**
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* @category zipping
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* @since 2.0.0
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*/
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export const zipWith = /*#__PURE__*/dual(3, (self, that, f) => flatMap(self, r => map(that, r2 => f(r, r2))));
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/**
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* @category combining
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* @since 2.0.0
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*/
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export const ap = /*#__PURE__*/dual(2, (self, that) => zipWith(self, that, (f, a) => f(a)));
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/**
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* Takes a structure of `Either`s and returns an `Either` of values with the same structure.
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*
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* - If a tuple is supplied, then the returned `Either` will contain a tuple with the same length.
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* - If a struct is supplied, then the returned `Either` will contain a struct with the same keys.
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* - If an iterable is supplied, then the returned `Either` will contain an array.
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*
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* @example
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* ```ts
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* import * as assert from "node:assert"
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* import { Either } from "effect"
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*
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* assert.deepStrictEqual(Either.all([Either.right(1), Either.right(2)]), Either.right([1, 2]))
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* assert.deepStrictEqual(Either.all({ right: Either.right(1), b: Either.right("hello") }), Either.right({ right: 1, b: "hello" }))
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* assert.deepStrictEqual(Either.all({ right: Either.right(1), b: Either.left("error") }), Either.left("error"))
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* ```
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*
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* @category combining
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* @since 2.0.0
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*/
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// @ts-expect-error
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export const all = input => {
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if (Symbol.iterator in input) {
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const out = [];
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for (const e of input) {
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if (isLeft(e)) {
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return e;
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}
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out.push(e.right);
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}
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return right(out);
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}
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const out = {};
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for (const key of Object.keys(input)) {
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const e = input[key];
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if (isLeft(e)) {
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return e;
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}
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out[key] = e.right;
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}
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return right(out);
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};
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/**
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* Returns an `Either` that swaps the error/success cases. This allows you to
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* use all methods on the error channel, possibly before flipping back.
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*
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* @since 2.0.0
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* @category mapping
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*/
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export const flip = self => isLeft(self) ? right(self.left) : left(self.right);
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const adapter = /*#__PURE__*/Gen.adapter();
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/**
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* @category generators
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* @since 2.0.0
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*/
|
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export const gen = (...args) => {
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const f = args.length === 1 ? args[0] : args[1].bind(args[0]);
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const iterator = f(adapter);
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let state = iterator.next();
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while (!state.done) {
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const current = Gen.isGenKind(state.value) ? state.value.value : Gen.yieldWrapGet(state.value);
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if (isLeft(current)) {
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return current;
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}
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state = iterator.next(current.right);
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}
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return right(state.value);
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};
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// -------------------------------------------------------------------------------------
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// do notation
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// -------------------------------------------------------------------------------------
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/**
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* 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`.
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*
|
|
* Here's how the do simulation works:
|
|
*
|
|
* 1. Start the do simulation using the `Do` value
|
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* 2. Within the do simulation scope, you can use the `bind` function to define variables and bind them to `Either` values
|
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* 3. You can accumulate multiple `bind` statements to define multiple variables within the scope
|
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* 4. Inside the do simulation scope, you can also use the `let` function to define variables and bind them to simple values
|
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*
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* @example
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* ```ts
|
|
* import * as assert from "node:assert"
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|
* import { Either, pipe } from "effect"
|
|
*
|
|
* const result = pipe(
|
|
* Either.Do,
|
|
* Either.bind("x", () => Either.right(2)),
|
|
* Either.bind("y", () => Either.right(3)),
|
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* Either.let("sum", ({ x, y }) => x + y)
|
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* )
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* assert.deepStrictEqual(result, Either.right({ x: 2, y: 3, sum: 5 }))
|
|
* ```
|
|
*
|
|
* @see {@link bind}
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* @see {@link bindTo}
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|
* @see {@link let_ let}
|
|
*
|
|
* @category do notation
|
|
* @since 2.0.0
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|
*/
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|
export const Do = /*#__PURE__*/right({});
|
|
/**
|
|
* 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 `Either` 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
|
|
*
|
|
* @example
|
|
* ```ts
|
|
* import * as assert from "node:assert"
|
|
* import { Either, pipe } from "effect"
|
|
*
|
|
* const result = pipe(
|
|
* Either.Do,
|
|
* Either.bind("x", () => Either.right(2)),
|
|
* Either.bind("y", () => Either.right(3)),
|
|
* Either.let("sum", ({ x, y }) => x + y)
|
|
* )
|
|
* assert.deepStrictEqual(result, Either.right({ 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 `Either` 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
|
|
*
|
|
* @example
|
|
* ```ts
|
|
* import * as assert from "node:assert"
|
|
* import { Either, pipe } from "effect"
|
|
*
|
|
* const result = pipe(
|
|
* Either.Do,
|
|
* Either.bind("x", () => Either.right(2)),
|
|
* Either.bind("y", () => Either.right(3)),
|
|
* Either.let("sum", ({ x, y }) => x + y)
|
|
* )
|
|
* assert.deepStrictEqual(result, Either.right({ 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 `Either` 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
|
|
*
|
|
* @example
|
|
* ```ts
|
|
* import * as assert from "node:assert"
|
|
* import { Either, pipe } from "effect"
|
|
*
|
|
* const result = pipe(
|
|
* Either.Do,
|
|
* Either.bind("x", () => Either.right(2)),
|
|
* Either.bind("y", () => Either.right(3)),
|
|
* Either.let("sum", ({ x, y }) => x + y)
|
|
* )
|
|
* assert.deepStrictEqual(result, Either.right({ x: 2, y: 3, sum: 5 }))
|
|
* ```
|
|
*
|
|
* @see {@link Do}
|
|
* @see {@link bindTo}
|
|
* @see {@link bind}
|
|
*
|
|
* @category do notation
|
|
* @since 2.0.0
|
|
*/
|
|
let_ as let };
|
|
/**
|
|
* Converts an `Option` of an `Either` into an `Either` of an `Option`.
|
|
*
|
|
* **Details**
|
|
*
|
|
* This function transforms an `Option<Either<A, E>>` into an
|
|
* `Either<Option<A>, E>`. If the `Option` is `None`, the resulting `Either`
|
|
* will be a `Right` with a `None` value. If the `Option` is `Some`, the
|
|
* inner `Either` will be executed, and its result wrapped in a `Some`.
|
|
*
|
|
* @example
|
|
* ```ts
|
|
* import { Effect, Either, Option } from "effect"
|
|
*
|
|
* // ┌─── Option<Either<number, never>>
|
|
* // ▼
|
|
* const maybe = Option.some(Either.right(42))
|
|
*
|
|
* // ┌─── Either<Option<number>, never, never>
|
|
* // ▼
|
|
* const result = Either.transposeOption(maybe)
|
|
*
|
|
* console.log(Effect.runSync(result))
|
|
* // Output: { _id: 'Option', _tag: 'Some', value: 42 }
|
|
* ```
|
|
*
|
|
* @since 3.14.0
|
|
* @category Optional Wrapping & Unwrapping
|
|
*/
|
|
export const transposeOption = self => {
|
|
return option_.isNone(self) ? right(option_.none) : map(self.value, option_.some);
|
|
};
|
|
/**
|
|
* Applies an `Either` on an `Option` and transposes the result.
|
|
*
|
|
* **Details**
|
|
*
|
|
* If the `Option` is `None`, the resulting `Either` will immediately succeed with a `Right` value of `None`.
|
|
* If the `Option` is `Some`, the transformation function will be applied to the inner value, and its result wrapped in a `Some`.
|
|
*
|
|
* @example
|
|
* ```ts
|
|
* import { Either, Option, pipe } from "effect"
|
|
*
|
|
* // ┌─── Either<Option<number>, never>>
|
|
* // ▼
|
|
* const noneResult = pipe(
|
|
* Option.none(),
|
|
* Either.transposeMapOption(() => Either.right(42)) // will not be executed
|
|
* )
|
|
* console.log(noneResult)
|
|
* // Output: { _id: 'Either', _tag: 'Right', right: { _id: 'Option', _tag: 'None' } }
|
|
*
|
|
* // ┌─── Either<Option<number>, never>>
|
|
* // ▼
|
|
* const someRightResult = pipe(
|
|
* Option.some(42),
|
|
* Either.transposeMapOption((value) => Either.right(value * 2))
|
|
* )
|
|
* console.log(someRightResult)
|
|
* // Output: { _id: 'Either', _tag: 'Right', right: { _id: 'Option', _tag: 'Some', value: 84 } }
|
|
* ```
|
|
*
|
|
* @since 3.15.0
|
|
* @category Optional Wrapping & Unwrapping
|
|
*/
|
|
export const transposeMapOption = /*#__PURE__*/dual(2, (self, f) => option_.isNone(self) ? right(option_.none) : map(f(self.value), option_.some));
|
|
//# sourceMappingURL=Either.js.map
|