/** * A synchronous, pure type for representing computations that can succeed * (`Success`) or fail (`Failure`). Unlike `Effect`, `Result` is * evaluated eagerly and carries no side effects. * * **Mental model** * * - `Result` is a discriminated union: `Success | Failure` * - `Success` wraps a value of type `A`, accessed via `.success` * - `Failure` wraps an error of type `E`, accessed via `.failure` * - `Result` is a monad: chain operations with {@link flatMap}, compose pipelines with `pipe` * - All operations are pure and return new `Result` values; the input is never mutated * - `Result` is yieldable in `Effect.gen`, producing the inner value or short-circuiting on failure * * **Common tasks** * * - Create from a value: {@link succeed}, {@link fail} * - Create from nullable: {@link fromNullishOr} * - Create from Option: {@link fromOption} * - Create from throwing code: {@link try_ try} * - Create from predicate: {@link liftPredicate} * - Transform: {@link map}, {@link mapError}, {@link mapBoth} * - Unwrap: {@link getOrElse}, {@link getOrNull}, {@link getOrUndefined}, {@link getOrThrow} * - Pattern match: {@link match} * - Sequence: {@link flatMap}, {@link andThen}, {@link all} * - Recover: {@link orElse} * - Filter: {@link filterOrFail} * - Convert to Option: {@link getSuccess}, {@link getFailure} * - Generator syntax: {@link gen} * - Do notation: {@link Do}, {@link bind}, {@link let_ let} * - Check variant: {@link isResult}, {@link isSuccess}, {@link isFailure} * * **Gotchas** * * - `E` defaults to `never`, so `Result` means a result that cannot fail * - {@link andThen} accepts a `Result`, a function returning a `Result`, a plain value, or a function returning a plain value; {@link flatMap} only accepts a function returning a `Result` * - {@link all} short-circuits on the first `Failure` and returns it; later elements are not inspected * - {@link getOrThrow} throws the raw failure value `E`; use {@link getOrThrowWith} for custom error objects * - {@link tap} runs a side-effect but does not change the result; its return value is ignored * * **Quickstart** * * **Example** (Parsing and validating with Result) * * ```ts * import { Result } from "effect" * * const parse = (input: string): Result.Result => * isNaN(Number(input)) * ? Result.fail("not a number") * : Result.succeed(Number(input)) * * const ensurePositive = (n: number): Result.Result => * n > 0 ? Result.succeed(n) : Result.fail("not positive") * * const result = Result.flatMap(parse("42"), ensurePositive) * * console.log(Result.getOrElse(result, (err) => `Error: ${err}`)) * // Output: 42 * ``` * * **See also** * * - {@link succeed} / {@link fail} to create values * - {@link match} to fold both branches * - {@link gen} for generator-based composition * * @since 4.0.0 */ import * as Equivalence from "./Equivalence.ts"; import type { LazyArg } from "./Function.ts"; import type { TypeLambda } from "./HKT.ts"; import type { Inspectable } from "./Inspectable.ts"; import type { Option } from "./Option.ts"; import type { Pipeable } from "./Pipeable.ts"; import type { Predicate, Refinement } from "./Predicate.ts"; import type { Covariant, NoInfer, NotFunction } from "./Types.ts"; import type * as Unify from "./Unify.ts"; import type * as Gen from "./Utils.ts"; declare const TypeId = "~effect/data/Result"; /** * A value that is either `Success` or `Failure`. * * - Use {@link succeed} / {@link fail} to construct * - Use {@link match} to fold both branches * - Use {@link isSuccess} / {@link isFailure} to narrow the type * * `E` defaults to `never`, so `Result` means a result that cannot fail. * * **Previously Known As** * * This API replaces the following from Effect 3.x: * * - `Either` * * **Example** (Creating and matching a Result) * * ```ts * import { Result } from "effect" * * const success = Result.succeed(42) * const failure = Result.fail("something went wrong") * * const message = Result.match(success, { * onSuccess: (value) => `Success: ${value}`, * onFailure: (error) => `Error: ${error}` * }) * console.log(message) * // Output: "Success: 42" * ``` * * @see {@link succeed} / {@link fail} to create values * @see {@link match} to fold both branches * @see {@link isSuccess} / {@link isFailure} for type guards * * @category Models * @since 4.0.0 */ export type Result = Success | Failure; /** * The failure variant of {@link Result}. Wraps an error of type `E`. * * - Access the error via the `.failure` property * - Use {@link isFailure} to narrow a `Result` to `Failure` * - Create with {@link fail} * * **Example** (Accessing the failure value) * * ```ts * import { Result } from "effect" * * const failure = Result.fail("Network error") * * if (Result.isFailure(failure)) { * console.log(failure.failure) * // Output: "Network error" * } * ``` * * @see {@link fail} to create a Failure * @see {@link isFailure} to narrow the type * @see {@link Success} for the other variant * * @category Models * @since 4.0.0 */ export interface Failure extends Pipeable, Inspectable { readonly _tag: "Failure"; readonly _op: "Failure"; readonly failure: E; readonly [TypeId]: { readonly _A: Covariant; readonly _E: Covariant; }; [Symbol.iterator](): ResultIterator>; [Unify.typeSymbol]?: unknown; [Unify.unifySymbol]?: ResultUnify; [Unify.ignoreSymbol]?: ResultUnifyIgnore; } /** * @since 4.0.0 * @category Models */ export interface ResultIterator> { next(...args: ReadonlyArray): IteratorResult>; } /** * The success variant of {@link Result}. Wraps a value of type `A`. * * - Access the value via the `.success` property * - Use {@link isSuccess} to narrow a `Result` to `Success` * - Create with {@link succeed} * * **Example** (Accessing the success value) * * ```ts * import { Result } from "effect" * * const success = Result.succeed(42) * * if (Result.isSuccess(success)) { * console.log(success.success) * // Output: 42 * } * ``` * * @see {@link succeed} to create a Success * @see {@link isSuccess} to narrow the type * @see {@link Failure} for the other variant * * @category Models * @since 4.0.0 */ export interface Success extends Pipeable, Inspectable { readonly _tag: "Success"; readonly _op: "Success"; readonly success: A; readonly [TypeId]: { readonly _A: Covariant; readonly _E: Covariant; }; [Symbol.iterator](): ResultIterator>; [Unify.typeSymbol]?: unknown; [Unify.unifySymbol]?: ResultUnify; [Unify.ignoreSymbol]?: ResultUnifyIgnore; } /** * Type-level utility for unifying `Result` types in generic contexts. * * This is an internal interface used by the Effect type system. You typically * do not need to reference it directly. * * @category Models * @since 4.0.0 */ export interface ResultUnify { Result?: () => T[Unify.typeSymbol] extends Result | infer _ ? Result : never; } /** * Marker interface for ignoring unification in `Result` types. * * This is an internal interface used by the Effect type system. You typically * do not need to reference it directly. * * @category Models * @since 4.0.0 */ export interface ResultUnifyIgnore { } /** * Higher-kinded type representation for `Result`. * * Used internally to integrate `Result` with generic type-class utilities * (e.g., `map`, `flatMap` abstractions). You typically do not need to * reference this directly. * * @category Type Lambdas * @since 4.0.0 */ export interface ResultTypeLambda extends TypeLambda { readonly type: Result; } /** * Namespace containing type-level utilities for extracting the inner types * of a `Result`. * * **Example** (Extracting inner types) * * ```ts * import type { Result } from "effect" * * type R = Result.Result * * // number * type A = Result.Result.Success * * // string * type E = Result.Result.Failure * ``` * * @category Type Level * @since 4.0.0 */ export declare namespace Result { /** * Extracts the failure type `E` from `Result`. * * @since 4.0.0 * @category Type Level */ type Failure> = [T] extends [Result] ? _E : never; /** * Extracts the success type `A` from `Result`. * * @since 4.0.0 * @category Type Level */ type Success> = [T] extends [Result] ? _A : never; } /** * Creates a `Result` holding a `Success` value. * * - Use when you have a value and want to lift it into the `Result` type * - The error type `E` defaults to `never` * - Does not mutate input; allocates a new `Success` wrapper * * **Previously Known As** * * This API replaces the following from Effect 3.x: * * - `Either.right` * * **Example** (Wrapping a value) * * ```ts * import { Result } from "effect" * * const result = Result.succeed(42) * * console.log(Result.isSuccess(result)) * // Output: true * ``` * * @see {@link fail} to create a Failure * @see {@link void} for a pre-built `Success` * * @category Constructors * @since 4.0.0 */ export declare const succeed: (right: A) => Result; /** * Creates a `Result` holding a `Failure` value. * * - Use when you want to represent a failed computation * - The success type `A` defaults to `never` * - Does not mutate input; allocates a new `Failure` wrapper * * **Previously Known As** * * This API replaces the following from Effect 3.x: * * - `Either.left` * * **Example** (Creating a failure) * * ```ts * import { Result } from "effect" * * const result = Result.fail("Something went wrong") * * console.log(Result.isFailure(result)) * // Output: true * ``` * * @see {@link succeed} to create a Success * @see {@link mapError} to transform the error * * @category Constructors * @since 4.0.0 */ export declare const fail: (left: E) => Result; declare const void_: Result; export { /** * A pre-built `Result` holding `undefined` as its success value. * * - Use when you need a `Result` that represents "completed with no meaningful value" * - Equivalent to `Result.succeed(undefined)` but avoids an extra allocation * * **Example** (Using void result) * * ```ts * import { Result } from "effect" * * const result: Result.Result = Result.void * * console.log(Result.isSuccess(result)) * // Output: true * ``` * * @see {@link succeed} * * @category Constructors * @since 4.0.0 */ void_ as void }; /** * A pre-built `Result` holding `undefined` as its failure value. * * - Use when you need a `Result` that represents "failed with no meaningful value" * - Equivalent to `Result.fail(undefined)` but avoids an extra allocation * * @see {@link fail} * * @category Constructors * @since 4.0.0 */ export declare const failVoid: Result; /** * Converts a possibly `null` or `undefined` value into a `Result`. * * - Non-nullish values become `Success>` * - `null` or `undefined` becomes `Failure` using the provided function * - Supports both data-first and data-last (piped) usage * - The `onNullish` callback receives the original value * * **Example** (Handling nullable values) * * ```ts * import { Result } from "effect" * * console.log(Result.fromNullishOr(1, () => "fallback")) * // Output: { _tag: "Success", success: 1, ... } * * console.log(Result.fromNullishOr(null, () => "fallback")) * // Output: { _tag: "Failure", failure: "fallback", ... } * ``` * * @see {@link fromOption} to convert from an Option * @see {@link succeed} / {@link fail} for direct construction * * @category Constructors * @since 4.0.0 */ export declare const fromNullishOr: { /** * Converts a possibly `null` or `undefined` value into a `Result`. * * - Non-nullish values become `Success>` * - `null` or `undefined` becomes `Failure` using the provided function * - Supports both data-first and data-last (piped) usage * - The `onNullish` callback receives the original value * * **Example** (Handling nullable values) * * ```ts * import { Result } from "effect" * * console.log(Result.fromNullishOr(1, () => "fallback")) * // Output: { _tag: "Success", success: 1, ... } * * console.log(Result.fromNullishOr(null, () => "fallback")) * // Output: { _tag: "Failure", failure: "fallback", ... } * ``` * * @see {@link fromOption} to convert from an Option * @see {@link succeed} / {@link fail} for direct construction * * @category Constructors * @since 4.0.0 */ (onNullish: (a: A) => E): (self: A) => Result, E>; /** * Converts a possibly `null` or `undefined` value into a `Result`. * * - Non-nullish values become `Success>` * - `null` or `undefined` becomes `Failure` using the provided function * - Supports both data-first and data-last (piped) usage * - The `onNullish` callback receives the original value * * **Example** (Handling nullable values) * * ```ts * import { Result } from "effect" * * console.log(Result.fromNullishOr(1, () => "fallback")) * // Output: { _tag: "Success", success: 1, ... } * * console.log(Result.fromNullishOr(null, () => "fallback")) * // Output: { _tag: "Failure", failure: "fallback", ... } * ``` * * @see {@link fromOption} to convert from an Option * @see {@link succeed} / {@link fail} for direct construction * * @category Constructors * @since 4.0.0 */ (self: A, onNullish: (a: A) => E): Result, E>; }; /** * Converts an `Option` into a `Result`. * * - `Some` becomes `Success` * - `None` becomes `Failure` using the provided function * - Supports both data-first and data-last (piped) usage * * **Example** (Converting an Option to a Result) * * ```ts * import { Option, Result } from "effect" * * const some = Result.fromOption(Option.some(1), () => "missing") * console.log(some) * // Output: { _tag: "Success", success: 1, ... } * * const none = Result.fromOption(Option.none(), () => "missing") * console.log(none) * // Output: { _tag: "Failure", failure: "missing", ... } * ``` * * @see {@link getSuccess} / {@link getFailure} to convert back to Option * @see {@link fromNullishOr} to convert from nullable values * * @category Constructors * @since 4.0.0 */ export declare const fromOption: { /** * Converts an `Option` into a `Result`. * * - `Some` becomes `Success` * - `None` becomes `Failure` using the provided function * - Supports both data-first and data-last (piped) usage * * **Example** (Converting an Option to a Result) * * ```ts * import { Option, Result } from "effect" * * const some = Result.fromOption(Option.some(1), () => "missing") * console.log(some) * // Output: { _tag: "Success", success: 1, ... } * * const none = Result.fromOption(Option.none(), () => "missing") * console.log(none) * // Output: { _tag: "Failure", failure: "missing", ... } * ``` * * @see {@link getSuccess} / {@link getFailure} to convert back to Option * @see {@link fromNullishOr} to convert from nullable values * * @category Constructors * @since 4.0.0 */ (onNone: () => E): (self: Option) => Result; /** * Converts an `Option` into a `Result`. * * - `Some` becomes `Success` * - `None` becomes `Failure` using the provided function * - Supports both data-first and data-last (piped) usage * * **Example** (Converting an Option to a Result) * * ```ts * import { Option, Result } from "effect" * * const some = Result.fromOption(Option.some(1), () => "missing") * console.log(some) * // Output: { _tag: "Success", success: 1, ... } * * const none = Result.fromOption(Option.none(), () => "missing") * console.log(none) * // Output: { _tag: "Failure", failure: "missing", ... } * ``` * * @see {@link getSuccess} / {@link getFailure} to convert back to Option * @see {@link fromNullishOr} to convert from nullable values * * @category Constructors * @since 4.0.0 */ (self: Option, onNone: () => E): Result; }; declare const try_: { (options: { readonly try: LazyArg; readonly catch: (error: unknown) => E; }): Result; (evaluate: LazyArg): Result; }; export { /** * Wraps a synchronous computation that may throw into a `Result`. * * - If the function returns normally, the result is `Success` * - If the function throws, the exception is caught and becomes `Failure` * - With a single function argument, the error type is `unknown` * - With `{ try, catch }` options, the `catch` function maps the thrown value to `E` * * **Example** (Catching JSON parse errors) * * ```ts * import { Result } from "effect" * * const ok = Result.try(() => JSON.parse('{"name": "Alice"}')) * console.log(ok) * // Output: { _tag: "Success", success: { name: "Alice" }, ... } * * const err = Result.try({ * try: () => JSON.parse("not json"), * catch: (e) => `Parse failed: ${e}` * }) * console.log(Result.isFailure(err)) * // Output: true * ``` * * @see {@link succeed} / {@link fail} for direct construction * @see {@link fromNullishOr} for nullable values * * @category Constructors * @since 4.0.0 */ try_ as try }; /** * Tests whether a value is a `Result` (either `Success` or `Failure`). * * - Use to validate unknown input before operating on it as a `Result` * - Returns `true` for both `Success` and `Failure` variants * - Acts as a TypeScript type guard, narrowing to `Result` * * **Example** (Checking if a value is a Result) * * ```ts * import { Result } from "effect" * * console.log(Result.isResult(Result.succeed(1))) * // Output: true * * console.log(Result.isResult({ value: 1 })) * // Output: false * ``` * * @see {@link isSuccess} / {@link isFailure} to narrow to a specific variant * * @category Type Guards * @since 4.0.0 */ export declare const isResult: (input: unknown) => input is Result; /** * Checks whether a `Result` is a `Failure`. * * - Acts as a TypeScript type guard, narrowing to `Failure` * - After narrowing, you can access `.failure` to read the error value * * **Example** (Narrowing to Failure) * * ```ts * import { Result } from "effect" * * const result = Result.fail("oops") * * if (Result.isFailure(result)) { * console.log(result.failure) * // Output: "oops" * } * ``` * * @see {@link isSuccess} for the opposite check * @see {@link isResult} to check if a value is any Result * * @category Type Guards * @since 4.0.0 */ export declare const isFailure: (self: Result) => self is Failure; /** * Checks whether a `Result` is a `Success`. * * - Acts as a TypeScript type guard, narrowing to `Success` * - After narrowing, you can access `.success` to read the value * * **Example** (Narrowing to Success) * * ```ts * import { Result } from "effect" * * const result = Result.succeed(42) * * if (Result.isSuccess(result)) { * console.log(result.success) * // Output: 42 * } * ``` * * @see {@link isFailure} for the opposite check * @see {@link isResult} to check if a value is any Result * * @category Type Guards * @since 4.0.0 */ export declare const isSuccess: (self: Result) => self is Success; /** * Extracts the success value as an `Option`, discarding the failure. * * - `Success` becomes `Some` * - `Failure` becomes `None` * - Use when you only care about the success case and want to discard error info * * **Example** (Extracting the success as an Option) * * ```ts * import { Option, Result } from "effect" * * console.log(Result.getSuccess(Result.succeed("ok"))) * // Output: { _tag: "Some", value: "ok" } * * console.log(Result.getSuccess(Result.fail("err"))) * // Output: { _tag: "None" } * ``` * * @see {@link getFailure} to extract the error instead * @see {@link fromOption} for the reverse conversion * * @category Getters * @since 4.0.0 */ export declare const getSuccess: (self: Result) => Option; /** * Extracts the failure value as an `Option`, discarding the success. * * - `Failure` becomes `Some` * - `Success` becomes `None` * - Use when you only care about the error case * * **Example** (Extracting the failure as an Option) * * ```ts * import { Option, Result } from "effect" * * console.log(Result.getFailure(Result.succeed("ok"))) * // Output: { _tag: "None" } * * console.log(Result.getFailure(Result.fail("err"))) * // Output: { _tag: "Some", value: "err" } * ``` * * @see {@link getSuccess} to extract the success instead * @see {@link fromOption} for the reverse conversion * * @category Getters * @since 4.0.0 */ export declare const getFailure: (self: Result) => Option; /** * Creates an `Equivalence` for comparing two `Result` values. * * - Two `Success` values are equal when the `success` equivalence says so * - Two `Failure` values are equal when the `failure` equivalence says so * - A `Success` and a `Failure` are never equal * * **Example** (Comparing Results for equality) * * ```ts * import { Equivalence, Result } from "effect" * * const eq = Result.makeEquivalence( * Equivalence.strictEqual(), * Equivalence.strictEqual() * ) * * console.log(eq(Result.succeed(1), Result.succeed(1))) * // Output: true * * console.log(eq(Result.succeed(1), Result.fail("x"))) * // Output: false * ``` * * @category Equivalence * @since 4.0.0 */ export declare const makeEquivalence: (success: Equivalence.Equivalence, failure: Equivalence.Equivalence) => Equivalence.Equivalence>; /** * Transforms both the success and failure channels of a `Result`. * * - Applies `onSuccess` if the result is a `Success` * - Applies `onFailure` if the result is a `Failure` * - Returns a new `Result`; does not mutate the input * - Use when you need to transform both channels in a single operation * * **Example** (Mapping both channels) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.succeed(1), * Result.mapBoth({ * onSuccess: (n) => n + 1, * onFailure: (e) => `Error: ${e}` * }) * ) * console.log(result) * // Output: { _tag: "Success", success: 2, ... } * ``` * * @see {@link map} to transform only the success value * @see {@link mapError} to transform only the error value * @see {@link match} to fold into a single value * * @category Mapping * @since 4.0.0 */ export declare const mapBoth: { /** * Transforms both the success and failure channels of a `Result`. * * - Applies `onSuccess` if the result is a `Success` * - Applies `onFailure` if the result is a `Failure` * - Returns a new `Result`; does not mutate the input * - Use when you need to transform both channels in a single operation * * **Example** (Mapping both channels) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.succeed(1), * Result.mapBoth({ * onSuccess: (n) => n + 1, * onFailure: (e) => `Error: ${e}` * }) * ) * console.log(result) * // Output: { _tag: "Success", success: 2, ... } * ``` * * @see {@link map} to transform only the success value * @see {@link mapError} to transform only the error value * @see {@link match} to fold into a single value * * @category Mapping * @since 4.0.0 */ (options: { readonly onFailure: (left: E) => E2; readonly onSuccess: (right: A) => A2; }): (self: Result) => Result; /** * Transforms both the success and failure channels of a `Result`. * * - Applies `onSuccess` if the result is a `Success` * - Applies `onFailure` if the result is a `Failure` * - Returns a new `Result`; does not mutate the input * - Use when you need to transform both channels in a single operation * * **Example** (Mapping both channels) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.succeed(1), * Result.mapBoth({ * onSuccess: (n) => n + 1, * onFailure: (e) => `Error: ${e}` * }) * ) * console.log(result) * // Output: { _tag: "Success", success: 2, ... } * ``` * * @see {@link map} to transform only the success value * @see {@link mapError} to transform only the error value * @see {@link match} to fold into a single value * * @category Mapping * @since 4.0.0 */ (self: Result, options: { readonly onFailure: (left: E) => E2; readonly onSuccess: (right: A) => A2; }): Result; }; /** * Transforms the failure channel of a `Result`, leaving the success channel unchanged. * * - If the result is a `Failure`, applies `f` to the error and returns a new `Failure` * - If the result is a `Success`, returns it as-is * - Does not mutate the input * * **Example** (Adding context to an error) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.fail("not found"), * Result.mapError((e) => `Error: ${e}`) * ) * console.log(result) * // Output: { _tag: "Failure", failure: "Error: not found", ... } * ``` * * @see {@link map} to transform only the success value * @see {@link mapBoth} to transform both channels * * @category Mapping * @since 4.0.0 */ export declare const mapError: { /** * Transforms the failure channel of a `Result`, leaving the success channel unchanged. * * - If the result is a `Failure`, applies `f` to the error and returns a new `Failure` * - If the result is a `Success`, returns it as-is * - Does not mutate the input * * **Example** (Adding context to an error) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.fail("not found"), * Result.mapError((e) => `Error: ${e}`) * ) * console.log(result) * // Output: { _tag: "Failure", failure: "Error: not found", ... } * ``` * * @see {@link map} to transform only the success value * @see {@link mapBoth} to transform both channels * * @category Mapping * @since 4.0.0 */ (f: (err: E) => E2): (self: Result) => Result; /** * Transforms the failure channel of a `Result`, leaving the success channel unchanged. * * - If the result is a `Failure`, applies `f` to the error and returns a new `Failure` * - If the result is a `Success`, returns it as-is * - Does not mutate the input * * **Example** (Adding context to an error) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.fail("not found"), * Result.mapError((e) => `Error: ${e}`) * ) * console.log(result) * // Output: { _tag: "Failure", failure: "Error: not found", ... } * ``` * * @see {@link map} to transform only the success value * @see {@link mapBoth} to transform both channels * * @category Mapping * @since 4.0.0 */ (self: Result, f: (err: E) => E2): Result; }; /** * Transforms the success channel of a `Result`, leaving the failure channel unchanged. * * - If the result is a `Success`, applies `f` to the value and returns a new `Success` * - If the result is a `Failure`, returns it as-is * - Does not mutate the input * - Use {@link flatMap} if `f` returns a `Result` (to avoid nested Results) * * **Example** (Doubling the success value) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.succeed(3), * Result.map((n) => n * 2) * ) * console.log(result) * // Output: { _tag: "Success", success: 6, ... } * ``` * * @see {@link mapError} to transform only the error value * @see {@link mapBoth} to transform both channels * @see {@link flatMap} when `f` returns a `Result` * * @category Mapping * @since 4.0.0 */ export declare const map: { /** * Transforms the success channel of a `Result`, leaving the failure channel unchanged. * * - If the result is a `Success`, applies `f` to the value and returns a new `Success` * - If the result is a `Failure`, returns it as-is * - Does not mutate the input * - Use {@link flatMap} if `f` returns a `Result` (to avoid nested Results) * * **Example** (Doubling the success value) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.succeed(3), * Result.map((n) => n * 2) * ) * console.log(result) * // Output: { _tag: "Success", success: 6, ... } * ``` * * @see {@link mapError} to transform only the error value * @see {@link mapBoth} to transform both channels * @see {@link flatMap} when `f` returns a `Result` * * @category Mapping * @since 4.0.0 */ (f: (ok: A) => A2): (self: Result) => Result; /** * Transforms the success channel of a `Result`, leaving the failure channel unchanged. * * - If the result is a `Success`, applies `f` to the value and returns a new `Success` * - If the result is a `Failure`, returns it as-is * - Does not mutate the input * - Use {@link flatMap} if `f` returns a `Result` (to avoid nested Results) * * **Example** (Doubling the success value) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.succeed(3), * Result.map((n) => n * 2) * ) * console.log(result) * // Output: { _tag: "Success", success: 6, ... } * ``` * * @see {@link mapError} to transform only the error value * @see {@link mapBoth} to transform both channels * @see {@link flatMap} when `f` returns a `Result` * * @category Mapping * @since 4.0.0 */ (self: Result, f: (ok: A) => A2): Result; }; /** * Folds a `Result` into a single value by applying one of two functions. * * - Applies `onSuccess` if the result is a `Success` * - Applies `onFailure` if the result is a `Failure` * - Both branches must return the same type (or a common supertype) * - Use when you need to "exit" the `Result` type and produce a plain value * * **Example** (Folding to a string) * * ```ts * import { pipe, Result } from "effect" * * const format = Result.match({ * onSuccess: (n: number) => `Got ${n}`, * onFailure: (e: string) => `Err: ${e}` * }) * * console.log(format(Result.succeed(42))) * // Output: "Got 42" * * console.log(format(Result.fail("timeout"))) * // Output: "Err: timeout" * ``` * * @see {@link merge} to extract `A | E` without mapping * @see {@link getOrElse} to unwrap only the success with a fallback * * @category Pattern Matching * @since 4.0.0 */ export declare const match: { /** * Folds a `Result` into a single value by applying one of two functions. * * - Applies `onSuccess` if the result is a `Success` * - Applies `onFailure` if the result is a `Failure` * - Both branches must return the same type (or a common supertype) * - Use when you need to "exit" the `Result` type and produce a plain value * * **Example** (Folding to a string) * * ```ts * import { pipe, Result } from "effect" * * const format = Result.match({ * onSuccess: (n: number) => `Got ${n}`, * onFailure: (e: string) => `Err: ${e}` * }) * * console.log(format(Result.succeed(42))) * // Output: "Got 42" * * console.log(format(Result.fail("timeout"))) * // Output: "Err: timeout" * ``` * * @see {@link merge} to extract `A | E` without mapping * @see {@link getOrElse} to unwrap only the success with a fallback * * @category Pattern Matching * @since 4.0.0 */ (options: { readonly onFailure: (error: E) => B; readonly onSuccess: (ok: A) => C; }): (self: Result) => B | C; /** * Folds a `Result` into a single value by applying one of two functions. * * - Applies `onSuccess` if the result is a `Success` * - Applies `onFailure` if the result is a `Failure` * - Both branches must return the same type (or a common supertype) * - Use when you need to "exit" the `Result` type and produce a plain value * * **Example** (Folding to a string) * * ```ts * import { pipe, Result } from "effect" * * const format = Result.match({ * onSuccess: (n: number) => `Got ${n}`, * onFailure: (e: string) => `Err: ${e}` * }) * * console.log(format(Result.succeed(42))) * // Output: "Got 42" * * console.log(format(Result.fail("timeout"))) * // Output: "Err: timeout" * ``` * * @see {@link merge} to extract `A | E` without mapping * @see {@link getOrElse} to unwrap only the success with a fallback * * @category Pattern Matching * @since 4.0.0 */ (self: Result, options: { readonly onFailure: (error: E) => B; readonly onSuccess: (ok: A) => C; }): B | C; }; /** * Lifts a value into a `Result` based on a predicate or refinement. * * - If the predicate returns `true`, the value becomes `Success` * - If the predicate returns `false`, `orFailWith` produces the error for `Failure` * - Also accepts a `Refinement` to narrow the success type * - Supports both data-first and data-last (piped) usage * * **Example** (Validating a number) * * ```ts * import { pipe, Result } from "effect" * * const ensurePositive = pipe( * 5, * Result.liftPredicate( * (n: number) => n > 0, * (n) => `${n} is not positive` * ) * ) * console.log(ensurePositive) * // Output: { _tag: "Success", success: 5, ... } * ``` * * @see {@link filterOrFail} to validate a value that is already in a `Result` * @see {@link fromNullishOr} for nullable-based construction * * @category Constructors * @since 4.0.0 */ export declare const liftPredicate: { /** * Lifts a value into a `Result` based on a predicate or refinement. * * - If the predicate returns `true`, the value becomes `Success` * - If the predicate returns `false`, `orFailWith` produces the error for `Failure` * - Also accepts a `Refinement` to narrow the success type * - Supports both data-first and data-last (piped) usage * * **Example** (Validating a number) * * ```ts * import { pipe, Result } from "effect" * * const ensurePositive = pipe( * 5, * Result.liftPredicate( * (n: number) => n > 0, * (n) => `${n} is not positive` * ) * ) * console.log(ensurePositive) * // Output: { _tag: "Success", success: 5, ... } * ``` * * @see {@link filterOrFail} to validate a value that is already in a `Result` * @see {@link fromNullishOr} for nullable-based construction * * @category Constructors * @since 4.0.0 */ (refinement: Refinement, orFailWith: (a: A) => E): (a: A) => Result; /** * Lifts a value into a `Result` based on a predicate or refinement. * * - If the predicate returns `true`, the value becomes `Success` * - If the predicate returns `false`, `orFailWith` produces the error for `Failure` * - Also accepts a `Refinement` to narrow the success type * - Supports both data-first and data-last (piped) usage * * **Example** (Validating a number) * * ```ts * import { pipe, Result } from "effect" * * const ensurePositive = pipe( * 5, * Result.liftPredicate( * (n: number) => n > 0, * (n) => `${n} is not positive` * ) * ) * console.log(ensurePositive) * // Output: { _tag: "Success", success: 5, ... } * ``` * * @see {@link filterOrFail} to validate a value that is already in a `Result` * @see {@link fromNullishOr} for nullable-based construction * * @category Constructors * @since 4.0.0 */ (predicate: Predicate, orFailWith: (a: A) => E): (a: B) => Result; /** * Lifts a value into a `Result` based on a predicate or refinement. * * - If the predicate returns `true`, the value becomes `Success` * - If the predicate returns `false`, `orFailWith` produces the error for `Failure` * - Also accepts a `Refinement` to narrow the success type * - Supports both data-first and data-last (piped) usage * * **Example** (Validating a number) * * ```ts * import { pipe, Result } from "effect" * * const ensurePositive = pipe( * 5, * Result.liftPredicate( * (n: number) => n > 0, * (n) => `${n} is not positive` * ) * ) * console.log(ensurePositive) * // Output: { _tag: "Success", success: 5, ... } * ``` * * @see {@link filterOrFail} to validate a value that is already in a `Result` * @see {@link fromNullishOr} for nullable-based construction * * @category Constructors * @since 4.0.0 */ (self: A, refinement: Refinement, orFailWith: (a: A) => E): Result; /** * Lifts a value into a `Result` based on a predicate or refinement. * * - If the predicate returns `true`, the value becomes `Success` * - If the predicate returns `false`, `orFailWith` produces the error for `Failure` * - Also accepts a `Refinement` to narrow the success type * - Supports both data-first and data-last (piped) usage * * **Example** (Validating a number) * * ```ts * import { pipe, Result } from "effect" * * const ensurePositive = pipe( * 5, * Result.liftPredicate( * (n: number) => n > 0, * (n) => `${n} is not positive` * ) * ) * console.log(ensurePositive) * // Output: { _tag: "Success", success: 5, ... } * ``` * * @see {@link filterOrFail} to validate a value that is already in a `Result` * @see {@link fromNullishOr} for nullable-based construction * * @category Constructors * @since 4.0.0 */ (self: B, predicate: Predicate, orFailWith: (a: A) => E): Result; }; /** * Validates the success value of a `Result` using a predicate, failing with a * custom error if the predicate returns `false`. * * - If the result is already a `Failure`, it is returned as-is * - If the predicate passes, the `Success` is returned unchanged * - If the predicate fails, `orFailWith` produces the error for a new `Failure` * - Also accepts a `Refinement` to narrow the success type * - The error type of the output is the union of both error types * * **Example** (Filtering a success value) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.succeed(0), * Result.filterOrFail( * (n) => n > 0, * (n) => `${n} is not positive` * ) * ) * console.log(result) * // Output: { _tag: "Failure", failure: "0 is not positive", ... } * ``` * * @see {@link liftPredicate} to create a `Result` from a raw value with a predicate * @see {@link flatMap} for general conditional chaining * * @since 4.0.0 * @category Filtering */ export declare const filterOrFail: { /** * Validates the success value of a `Result` using a predicate, failing with a * custom error if the predicate returns `false`. * * - If the result is already a `Failure`, it is returned as-is * - If the predicate passes, the `Success` is returned unchanged * - If the predicate fails, `orFailWith` produces the error for a new `Failure` * - Also accepts a `Refinement` to narrow the success type * - The error type of the output is the union of both error types * * **Example** (Filtering a success value) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.succeed(0), * Result.filterOrFail( * (n) => n > 0, * (n) => `${n} is not positive` * ) * ) * console.log(result) * // Output: { _tag: "Failure", failure: "0 is not positive", ... } * ``` * * @see {@link liftPredicate} to create a `Result` from a raw value with a predicate * @see {@link flatMap} for general conditional chaining * * @since 4.0.0 * @category Filtering */ (refinement: Refinement, B>, orFailWith: (value: NoInfer) => E2): (self: Result) => Result; /** * Validates the success value of a `Result` using a predicate, failing with a * custom error if the predicate returns `false`. * * - If the result is already a `Failure`, it is returned as-is * - If the predicate passes, the `Success` is returned unchanged * - If the predicate fails, `orFailWith` produces the error for a new `Failure` * - Also accepts a `Refinement` to narrow the success type * - The error type of the output is the union of both error types * * **Example** (Filtering a success value) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.succeed(0), * Result.filterOrFail( * (n) => n > 0, * (n) => `${n} is not positive` * ) * ) * console.log(result) * // Output: { _tag: "Failure", failure: "0 is not positive", ... } * ``` * * @see {@link liftPredicate} to create a `Result` from a raw value with a predicate * @see {@link flatMap} for general conditional chaining * * @since 4.0.0 * @category Filtering */ (predicate: Predicate>, orFailWith: (value: NoInfer) => E2): (self: Result) => Result; /** * Validates the success value of a `Result` using a predicate, failing with a * custom error if the predicate returns `false`. * * - If the result is already a `Failure`, it is returned as-is * - If the predicate passes, the `Success` is returned unchanged * - If the predicate fails, `orFailWith` produces the error for a new `Failure` * - Also accepts a `Refinement` to narrow the success type * - The error type of the output is the union of both error types * * **Example** (Filtering a success value) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.succeed(0), * Result.filterOrFail( * (n) => n > 0, * (n) => `${n} is not positive` * ) * ) * console.log(result) * // Output: { _tag: "Failure", failure: "0 is not positive", ... } * ``` * * @see {@link liftPredicate} to create a `Result` from a raw value with a predicate * @see {@link flatMap} for general conditional chaining * * @since 4.0.0 * @category Filtering */ (self: Result, refinement: Refinement, orFailWith: (value: A) => E2): Result; /** * Validates the success value of a `Result` using a predicate, failing with a * custom error if the predicate returns `false`. * * - If the result is already a `Failure`, it is returned as-is * - If the predicate passes, the `Success` is returned unchanged * - If the predicate fails, `orFailWith` produces the error for a new `Failure` * - Also accepts a `Refinement` to narrow the success type * - The error type of the output is the union of both error types * * **Example** (Filtering a success value) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.succeed(0), * Result.filterOrFail( * (n) => n > 0, * (n) => `${n} is not positive` * ) * ) * console.log(result) * // Output: { _tag: "Failure", failure: "0 is not positive", ... } * ``` * * @see {@link liftPredicate} to create a `Result` from a raw value with a predicate * @see {@link flatMap} for general conditional chaining * * @since 4.0.0 * @category Filtering */ (self: Result, predicate: Predicate, orFailWith: (value: A) => E2): Result; }; /** * Unwraps a `Result` into `A | E` by returning the inner value regardless * of whether it is a success or failure. * * - `Success` returns `A` * - `Failure` returns `E` * - Useful when both channels share a compatible type * * **Example** (Extracting the inner value) * * ```ts * import { Result } from "effect" * * console.log(Result.merge(Result.succeed(42))) * // Output: 42 * * console.log(Result.merge(Result.fail("error"))) * // Output: "error" * ``` * * @see {@link match} to map each branch to a common type * @see {@link getOrElse} to provide a fallback for failures * * @category Getters * @since 4.0.0 */ export declare const merge: (self: Result) => E | A; /** * Extracts the success value, or computes a fallback from the error. * * - `Success` returns the inner value * - `Failure` applies `onFailure` to the error and returns the result * - The return type is `A | A2` (union of both branches) * * **Example** (Providing a fallback) * * ```ts * import { Result } from "effect" * * console.log(Result.getOrElse(Result.succeed(1), () => 0)) * // Output: 1 * * console.log(Result.getOrElse(Result.fail("err"), () => 0)) * // Output: 0 * ``` * * @see {@link getOrNull} / {@link getOrUndefined} for simpler fallbacks * @see {@link getOrThrow} to throw on failure * @see {@link match} to map both branches * * @category Getters * @since 4.0.0 */ export declare const getOrElse: { /** * Extracts the success value, or computes a fallback from the error. * * - `Success` returns the inner value * - `Failure` applies `onFailure` to the error and returns the result * - The return type is `A | A2` (union of both branches) * * **Example** (Providing a fallback) * * ```ts * import { Result } from "effect" * * console.log(Result.getOrElse(Result.succeed(1), () => 0)) * // Output: 1 * * console.log(Result.getOrElse(Result.fail("err"), () => 0)) * // Output: 0 * ``` * * @see {@link getOrNull} / {@link getOrUndefined} for simpler fallbacks * @see {@link getOrThrow} to throw on failure * @see {@link match} to map both branches * * @category Getters * @since 4.0.0 */ (onFailure: (err: E) => A2): (self: Result) => A2 | A; /** * Extracts the success value, or computes a fallback from the error. * * - `Success` returns the inner value * - `Failure` applies `onFailure` to the error and returns the result * - The return type is `A | A2` (union of both branches) * * **Example** (Providing a fallback) * * ```ts * import { Result } from "effect" * * console.log(Result.getOrElse(Result.succeed(1), () => 0)) * // Output: 1 * * console.log(Result.getOrElse(Result.fail("err"), () => 0)) * // Output: 0 * ``` * * @see {@link getOrNull} / {@link getOrUndefined} for simpler fallbacks * @see {@link getOrThrow} to throw on failure * @see {@link match} to map both branches * * @category Getters * @since 4.0.0 */ (self: Result, onFailure: (err: E) => A2): A | A2; }; /** * Extracts the success value, or returns `null` on failure. * * - `Success` returns `A` * - `Failure` returns `null` * - Convenient for interop with APIs that use `null` to represent absence * * **Example** (Unwrapping to nullable) * * ```ts * import { Result } from "effect" * * console.log(Result.getOrNull(Result.succeed(1))) * // Output: 1 * * console.log(Result.getOrNull(Result.fail("err"))) * // Output: null * ``` * * @see {@link getOrUndefined} to return `undefined` instead * @see {@link getOrElse} for a custom fallback * * @category Getters * @since 4.0.0 */ export declare const getOrNull: (self: Result) => A | null; /** * Extracts the success value, or returns `undefined` on failure. * * - `Success` returns `A` * - `Failure` returns `undefined` * - Convenient for interop with APIs that use `undefined` to represent absence * * **Example** (Unwrapping to optional) * * ```ts * import { Result } from "effect" * * console.log(Result.getOrUndefined(Result.succeed(1))) * // Output: 1 * * console.log(Result.getOrUndefined(Result.fail("err"))) * // Output: undefined * ``` * * @see {@link getOrNull} to return `null` instead * @see {@link getOrElse} for a custom fallback * * @category Getters * @since 4.0.0 */ export declare const getOrUndefined: (self: Result) => A | undefined; /** * Extracts the success value or throws a custom error derived from the failure. * * - `Success` returns `A` * - `Failure` throws the value returned by `onFailure(e)` * - Use when you want to convert a `Result` into a thrown exception with a * custom error message or error type * * **Example** (Throwing a custom error) * * ```ts * import { Result } from "effect" * * console.log( * Result.getOrThrowWith(Result.succeed(1), () => new Error("fail")) * ) * // Output: 1 * * // This would throw: new Error("Unexpected: oops") * // Result.getOrThrowWith( * // Result.fail("oops"), * // (err) => new Error(`Unexpected: ${err}`) * // ) * ``` * * @see {@link getOrThrow} to throw the raw failure value * @see {@link getOrElse} for a non-throwing alternative * * @category Getters * @since 4.0.0 */ export declare const getOrThrowWith: { /** * Extracts the success value or throws a custom error derived from the failure. * * - `Success` returns `A` * - `Failure` throws the value returned by `onFailure(e)` * - Use when you want to convert a `Result` into a thrown exception with a * custom error message or error type * * **Example** (Throwing a custom error) * * ```ts * import { Result } from "effect" * * console.log( * Result.getOrThrowWith(Result.succeed(1), () => new Error("fail")) * ) * // Output: 1 * * // This would throw: new Error("Unexpected: oops") * // Result.getOrThrowWith( * // Result.fail("oops"), * // (err) => new Error(`Unexpected: ${err}`) * // ) * ``` * * @see {@link getOrThrow} to throw the raw failure value * @see {@link getOrElse} for a non-throwing alternative * * @category Getters * @since 4.0.0 */ (onFailure: (err: E) => unknown): (self: Result) => A; /** * Extracts the success value or throws a custom error derived from the failure. * * - `Success` returns `A` * - `Failure` throws the value returned by `onFailure(e)` * - Use when you want to convert a `Result` into a thrown exception with a * custom error message or error type * * **Example** (Throwing a custom error) * * ```ts * import { Result } from "effect" * * console.log( * Result.getOrThrowWith(Result.succeed(1), () => new Error("fail")) * ) * // Output: 1 * * // This would throw: new Error("Unexpected: oops") * // Result.getOrThrowWith( * // Result.fail("oops"), * // (err) => new Error(`Unexpected: ${err}`) * // ) * ``` * * @see {@link getOrThrow} to throw the raw failure value * @see {@link getOrElse} for a non-throwing alternative * * @category Getters * @since 4.0.0 */ (self: Result, onFailure: (err: E) => unknown): A; }; /** * Extracts the success value or throws the raw failure value `E`. * * - `Success` returns `A` * - `Failure` throws `E` directly * - Use {@link getOrThrowWith} for a custom error object * * **Example** (Unwrapping or throwing) * * ```ts * import { Result } from "effect" * * console.log(Result.getOrThrow(Result.succeed(1))) * // Output: 1 * * // This would throw the string "error": * // Result.getOrThrow(Result.fail("error")) * ``` * * @see {@link getOrThrowWith} for custom error mapping * @see {@link getOrElse} for a non-throwing alternative * * @category Getters * @since 4.0.0 */ export declare const getOrThrow: (self: Result) => A; /** * Returns the original `Result` if it is a `Success`, otherwise applies * `that` to the error and returns the resulting `Result`. * * - `Success` is returned unchanged * - `Failure` calls `that(e)` to produce a new `Result` * - Use to provide a recovery path or fallback computation on failure * * **Example** (Recovering from a failure) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.fail("primary failed"), * Result.orElse(() => Result.succeed(99)) * ) * console.log(result) * // Output: { _tag: "Success", success: 99, ... } * ``` * * @see {@link getOrElse} to unwrap with a fallback value (not a Result) * @see {@link mapError} to transform the error without recovering * * @category Error Handling * @since 4.0.0 */ export declare const orElse: { /** * Returns the original `Result` if it is a `Success`, otherwise applies * `that` to the error and returns the resulting `Result`. * * - `Success` is returned unchanged * - `Failure` calls `that(e)` to produce a new `Result` * - Use to provide a recovery path or fallback computation on failure * * **Example** (Recovering from a failure) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.fail("primary failed"), * Result.orElse(() => Result.succeed(99)) * ) * console.log(result) * // Output: { _tag: "Success", success: 99, ... } * ``` * * @see {@link getOrElse} to unwrap with a fallback value (not a Result) * @see {@link mapError} to transform the error without recovering * * @category Error Handling * @since 4.0.0 */ (that: (err: E) => Result): (self: Result) => Result; /** * Returns the original `Result` if it is a `Success`, otherwise applies * `that` to the error and returns the resulting `Result`. * * - `Success` is returned unchanged * - `Failure` calls `that(e)` to produce a new `Result` * - Use to provide a recovery path or fallback computation on failure * * **Example** (Recovering from a failure) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.fail("primary failed"), * Result.orElse(() => Result.succeed(99)) * ) * console.log(result) * // Output: { _tag: "Success", success: 99, ... } * ``` * * @see {@link getOrElse} to unwrap with a fallback value (not a Result) * @see {@link mapError} to transform the error without recovering * * @category Error Handling * @since 4.0.0 */ (self: Result, that: (err: E) => Result): Result; }; /** * Chains a function that returns a `Result` onto a successful value. * * - If `self` is a `Success`, applies `f` to the value and returns the resulting `Result` * - If `self` is a `Failure`, short-circuits and returns it unchanged * - The error types are merged into a union (`E | E2`) * - This is the monadic `bind` / `>>=` for `Result` * * **Example** (Sequential validation) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.succeed(5), * Result.flatMap((n) => * n > 0 ? Result.succeed(n * 2) : Result.fail("not positive") * ) * ) * console.log(result) * // Output: { _tag: "Success", success: 10, ... } * ``` * * @see {@link andThen} for a more flexible variant that also accepts plain values * @see {@link map} when `f` does not return a `Result` * * @category Sequencing * @since 4.0.0 */ export declare const flatMap: { /** * Chains a function that returns a `Result` onto a successful value. * * - If `self` is a `Success`, applies `f` to the value and returns the resulting `Result` * - If `self` is a `Failure`, short-circuits and returns it unchanged * - The error types are merged into a union (`E | E2`) * - This is the monadic `bind` / `>>=` for `Result` * * **Example** (Sequential validation) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.succeed(5), * Result.flatMap((n) => * n > 0 ? Result.succeed(n * 2) : Result.fail("not positive") * ) * ) * console.log(result) * // Output: { _tag: "Success", success: 10, ... } * ``` * * @see {@link andThen} for a more flexible variant that also accepts plain values * @see {@link map} when `f` does not return a `Result` * * @category Sequencing * @since 4.0.0 */ (f: (a: A) => Result): (self: Result) => Result; /** * Chains a function that returns a `Result` onto a successful value. * * - If `self` is a `Success`, applies `f` to the value and returns the resulting `Result` * - If `self` is a `Failure`, short-circuits and returns it unchanged * - The error types are merged into a union (`E | E2`) * - This is the monadic `bind` / `>>=` for `Result` * * **Example** (Sequential validation) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.succeed(5), * Result.flatMap((n) => * n > 0 ? Result.succeed(n * 2) : Result.fail("not positive") * ) * ) * console.log(result) * // Output: { _tag: "Success", success: 10, ... } * ``` * * @see {@link andThen} for a more flexible variant that also accepts plain values * @see {@link map} when `f` does not return a `Result` * * @category Sequencing * @since 4.0.0 */ (self: Result, f: (a: A) => Result): Result; }; /** * A flexible variant of {@link flatMap} that accepts multiple input shapes. * * The second argument can be: * - A function `(a: A) => Result` (same as `flatMap`) * - A function `(a: A) => A2` (auto-wrapped in `succeed`) * - A `Result` value (ignores the success of `self`) * - A plain value `A2` (auto-wrapped in `succeed`, ignores `self`) * * If `self` is a `Failure`, the second argument is never evaluated. * * **Example** (Using andThen with different argument types) * * ```ts * import { pipe, Result } from "effect" * * // With a function returning a Result * const a = pipe( * Result.succeed(1), * Result.andThen((n) => Result.succeed(n + 1)) * ) * * // With a plain mapping function * const b = pipe( * Result.succeed(1), * Result.andThen((n) => n + 1) * ) * * // With a constant value * const c = pipe(Result.succeed(1), Result.andThen("done")) * * console.log(a, b, c) * ``` * * @see {@link flatMap} for the stricter variant (function returning Result only) * @see {@link map} when you always return a plain value * * @category Sequencing * @since 4.0.0 */ export declare const andThen: { /** * A flexible variant of {@link flatMap} that accepts multiple input shapes. * * The second argument can be: * - A function `(a: A) => Result` (same as `flatMap`) * - A function `(a: A) => A2` (auto-wrapped in `succeed`) * - A `Result` value (ignores the success of `self`) * - A plain value `A2` (auto-wrapped in `succeed`, ignores `self`) * * If `self` is a `Failure`, the second argument is never evaluated. * * **Example** (Using andThen with different argument types) * * ```ts * import { pipe, Result } from "effect" * * // With a function returning a Result * const a = pipe( * Result.succeed(1), * Result.andThen((n) => Result.succeed(n + 1)) * ) * * // With a plain mapping function * const b = pipe( * Result.succeed(1), * Result.andThen((n) => n + 1) * ) * * // With a constant value * const c = pipe(Result.succeed(1), Result.andThen("done")) * * console.log(a, b, c) * ``` * * @see {@link flatMap} for the stricter variant (function returning Result only) * @see {@link map} when you always return a plain value * * @category Sequencing * @since 4.0.0 */ (f: (a: A) => Result): (self: Result) => Result; /** * A flexible variant of {@link flatMap} that accepts multiple input shapes. * * The second argument can be: * - A function `(a: A) => Result` (same as `flatMap`) * - A function `(a: A) => A2` (auto-wrapped in `succeed`) * - A `Result` value (ignores the success of `self`) * - A plain value `A2` (auto-wrapped in `succeed`, ignores `self`) * * If `self` is a `Failure`, the second argument is never evaluated. * * **Example** (Using andThen with different argument types) * * ```ts * import { pipe, Result } from "effect" * * // With a function returning a Result * const a = pipe( * Result.succeed(1), * Result.andThen((n) => Result.succeed(n + 1)) * ) * * // With a plain mapping function * const b = pipe( * Result.succeed(1), * Result.andThen((n) => n + 1) * ) * * // With a constant value * const c = pipe(Result.succeed(1), Result.andThen("done")) * * console.log(a, b, c) * ``` * * @see {@link flatMap} for the stricter variant (function returning Result only) * @see {@link map} when you always return a plain value * * @category Sequencing * @since 4.0.0 */ (f: Result): (self: Result) => Result; /** * A flexible variant of {@link flatMap} that accepts multiple input shapes. * * The second argument can be: * - A function `(a: A) => Result` (same as `flatMap`) * - A function `(a: A) => A2` (auto-wrapped in `succeed`) * - A `Result` value (ignores the success of `self`) * - A plain value `A2` (auto-wrapped in `succeed`, ignores `self`) * * If `self` is a `Failure`, the second argument is never evaluated. * * **Example** (Using andThen with different argument types) * * ```ts * import { pipe, Result } from "effect" * * // With a function returning a Result * const a = pipe( * Result.succeed(1), * Result.andThen((n) => Result.succeed(n + 1)) * ) * * // With a plain mapping function * const b = pipe( * Result.succeed(1), * Result.andThen((n) => n + 1) * ) * * // With a constant value * const c = pipe(Result.succeed(1), Result.andThen("done")) * * console.log(a, b, c) * ``` * * @see {@link flatMap} for the stricter variant (function returning Result only) * @see {@link map} when you always return a plain value * * @category Sequencing * @since 4.0.0 */ (f: (a: A) => A2): (self: Result) => Result; /** * A flexible variant of {@link flatMap} that accepts multiple input shapes. * * The second argument can be: * - A function `(a: A) => Result` (same as `flatMap`) * - A function `(a: A) => A2` (auto-wrapped in `succeed`) * - A `Result` value (ignores the success of `self`) * - A plain value `A2` (auto-wrapped in `succeed`, ignores `self`) * * If `self` is a `Failure`, the second argument is never evaluated. * * **Example** (Using andThen with different argument types) * * ```ts * import { pipe, Result } from "effect" * * // With a function returning a Result * const a = pipe( * Result.succeed(1), * Result.andThen((n) => Result.succeed(n + 1)) * ) * * // With a plain mapping function * const b = pipe( * Result.succeed(1), * Result.andThen((n) => n + 1) * ) * * // With a constant value * const c = pipe(Result.succeed(1), Result.andThen("done")) * * console.log(a, b, c) * ``` * * @see {@link flatMap} for the stricter variant (function returning Result only) * @see {@link map} when you always return a plain value * * @category Sequencing * @since 4.0.0 */ (right: NotFunction): (self: Result) => Result; /** * A flexible variant of {@link flatMap} that accepts multiple input shapes. * * The second argument can be: * - A function `(a: A) => Result` (same as `flatMap`) * - A function `(a: A) => A2` (auto-wrapped in `succeed`) * - A `Result` value (ignores the success of `self`) * - A plain value `A2` (auto-wrapped in `succeed`, ignores `self`) * * If `self` is a `Failure`, the second argument is never evaluated. * * **Example** (Using andThen with different argument types) * * ```ts * import { pipe, Result } from "effect" * * // With a function returning a Result * const a = pipe( * Result.succeed(1), * Result.andThen((n) => Result.succeed(n + 1)) * ) * * // With a plain mapping function * const b = pipe( * Result.succeed(1), * Result.andThen((n) => n + 1) * ) * * // With a constant value * const c = pipe(Result.succeed(1), Result.andThen("done")) * * console.log(a, b, c) * ``` * * @see {@link flatMap} for the stricter variant (function returning Result only) * @see {@link map} when you always return a plain value * * @category Sequencing * @since 4.0.0 */ (self: Result, f: (a: A) => Result): Result; /** * A flexible variant of {@link flatMap} that accepts multiple input shapes. * * The second argument can be: * - A function `(a: A) => Result` (same as `flatMap`) * - A function `(a: A) => A2` (auto-wrapped in `succeed`) * - A `Result` value (ignores the success of `self`) * - A plain value `A2` (auto-wrapped in `succeed`, ignores `self`) * * If `self` is a `Failure`, the second argument is never evaluated. * * **Example** (Using andThen with different argument types) * * ```ts * import { pipe, Result } from "effect" * * // With a function returning a Result * const a = pipe( * Result.succeed(1), * Result.andThen((n) => Result.succeed(n + 1)) * ) * * // With a plain mapping function * const b = pipe( * Result.succeed(1), * Result.andThen((n) => n + 1) * ) * * // With a constant value * const c = pipe(Result.succeed(1), Result.andThen("done")) * * console.log(a, b, c) * ``` * * @see {@link flatMap} for the stricter variant (function returning Result only) * @see {@link map} when you always return a plain value * * @category Sequencing * @since 4.0.0 */ (self: Result, f: Result): Result; /** * A flexible variant of {@link flatMap} that accepts multiple input shapes. * * The second argument can be: * - A function `(a: A) => Result` (same as `flatMap`) * - A function `(a: A) => A2` (auto-wrapped in `succeed`) * - A `Result` value (ignores the success of `self`) * - A plain value `A2` (auto-wrapped in `succeed`, ignores `self`) * * If `self` is a `Failure`, the second argument is never evaluated. * * **Example** (Using andThen with different argument types) * * ```ts * import { pipe, Result } from "effect" * * // With a function returning a Result * const a = pipe( * Result.succeed(1), * Result.andThen((n) => Result.succeed(n + 1)) * ) * * // With a plain mapping function * const b = pipe( * Result.succeed(1), * Result.andThen((n) => n + 1) * ) * * // With a constant value * const c = pipe(Result.succeed(1), Result.andThen("done")) * * console.log(a, b, c) * ``` * * @see {@link flatMap} for the stricter variant (function returning Result only) * @see {@link map} when you always return a plain value * * @category Sequencing * @since 4.0.0 */ (self: Result, f: (a: A) => A2): Result; /** * A flexible variant of {@link flatMap} that accepts multiple input shapes. * * The second argument can be: * - A function `(a: A) => Result` (same as `flatMap`) * - A function `(a: A) => A2` (auto-wrapped in `succeed`) * - A `Result` value (ignores the success of `self`) * - A plain value `A2` (auto-wrapped in `succeed`, ignores `self`) * * If `self` is a `Failure`, the second argument is never evaluated. * * **Example** (Using andThen with different argument types) * * ```ts * import { pipe, Result } from "effect" * * // With a function returning a Result * const a = pipe( * Result.succeed(1), * Result.andThen((n) => Result.succeed(n + 1)) * ) * * // With a plain mapping function * const b = pipe( * Result.succeed(1), * Result.andThen((n) => n + 1) * ) * * // With a constant value * const c = pipe(Result.succeed(1), Result.andThen("done")) * * console.log(a, b, c) * ``` * * @see {@link flatMap} for the stricter variant (function returning Result only) * @see {@link map} when you always return a plain value * * @category Sequencing * @since 4.0.0 */ (self: Result, f: NotFunction): Result; }; /** * Collects a structure of `Result`s into a single `Result` of collected values. * * Accepts: * - A tuple/array: returns `Result` with a tuple/array of success values * - A struct (record): returns `Result` with a struct of success values * - An iterable: returns `Result` with an array of success values * * Short-circuits on the first `Failure` encountered; later elements are not inspected. * * **Example** (Collecting a tuple and a struct) * * ```ts * import { Result } from "effect" * * // Tuple * const tuple = Result.all([Result.succeed(1), Result.succeed("two")]) * console.log(tuple) * // Output: { _tag: "Success", success: [1, "two"], ... } * * // Struct * const struct = Result.all({ x: Result.succeed(1), y: Result.fail("err") }) * console.log(struct) * // Output: { _tag: "Failure", failure: "err", ... } * ``` * * @see {@link flatMap} for chaining two Results sequentially * @see {@link gen} for generator-based composition of multiple Results * * @category Sequencing * @since 4.0.0 */ export declare const all: > | Record>>(input: I) => [I] extends [ReadonlyArray>] ? Result<{ -readonly [K in keyof I]: [I[K]] extends [Result] ? R : never; }, I[number] extends never ? never : [I[number]] extends [Result] ? L : never> : [I] extends [Iterable>] ? Result, L> : Result<{ -readonly [K in keyof I]: [I[K]] extends [Result] ? R : never; }, I[keyof I] extends never ? never : [I[keyof I]] extends [Result] ? L : never>; /** * Swaps the success and failure channels of a `Result`. * * - `Success` becomes `Failure` (i.e., `Result`) * - `Failure` becomes `Success` (i.e., `Result`) * - Useful when you want to apply success-oriented operations (like `map`) * to the error channel, then flip back * * **Example** (Swapping channels) * * ```ts * import { Result } from "effect" * * console.log(Result.flip(Result.succeed(42))) * // Output: { _tag: "Failure", failure: 42, ... } * * console.log(Result.flip(Result.fail("error"))) * // Output: { _tag: "Success", success: "error", ... } * ``` * * @see {@link mapError} to transform the error without swapping * * @category Utilities * @since 4.0.0 */ export declare const flip: (self: Result) => Result; /** * Generator-based syntax for composing `Result` values sequentially. * * - Use `yield*` to unwrap a `Result` inside the generator; if any yielded * `Result` is a `Failure`, the generator short-circuits and returns that failure * - The return value of the generator is wrapped in `Success` * - Evaluated eagerly and synchronously (unlike `Effect.gen`) * * **Example** (Composing multiple Results) * * ```ts * import { Result } from "effect" * * const result = Result.gen(function*() { * const a = yield* Result.succeed(1) * const b = yield* Result.succeed(2) * return a + b * }) * * console.log(result) * // Output: { _tag: "Success", success: 3, ... } * ``` * * @see {@link flatMap} for point-free sequential composition * @see {@link all} to collect multiple independent Results * * @category Generators * @since 4.0.0 */ export declare const gen: Gen.Gen; /** * Starting point for the "do notation" simulation with `Result`. * * Creates a `Result<{}>` (success with an empty object). Use with * {@link bind} to add `Result`-producing fields and {@link let_ let} * to add pure computed fields. * * **Example** (Building an object step by step) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.Do, * Result.bind("x", () => Result.succeed(2)), * Result.bind("y", () => Result.succeed(3)), * Result.let("sum", ({ x, y }) => x + y) * ) * console.log(result) * // Output: { _tag: "Success", success: { x: 2, y: 3, sum: 5 }, ... } * ``` * * @see {@link bind} to add Result-producing fields * @see {@link let_ let} to add pure computed fields * @see {@link gen} for an alternative generator-based syntax * * @category Do Notation * @since 4.0.0 */ export declare const Do: Result<{}>; /** * Adds a named field to the do-notation accumulator by running a `Result`-producing * function that receives the current accumulated object. * * - Short-circuits on the first `Failure` * - The field name must not collide with existing keys * - Use {@link let_ let} for pure (non-Result) computed fields * * **Example** (Binding Result values) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.Do, * Result.bind("x", () => Result.succeed(2)), * Result.bind("y", ({ x }) => Result.succeed(x + 3)) * ) * console.log(result) * // Output: { _tag: "Success", success: { x: 2, y: 5 }, ... } * ``` * * @see {@link Do} to start the do-notation chain * @see {@link let_ let} for pure computed fields * @see {@link bindTo} to wrap an initial Result into a named field * * @category Do Notation * @since 4.0.0 */ export declare const bind: { /** * Adds a named field to the do-notation accumulator by running a `Result`-producing * function that receives the current accumulated object. * * - Short-circuits on the first `Failure` * - The field name must not collide with existing keys * - Use {@link let_ let} for pure (non-Result) computed fields * * **Example** (Binding Result values) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.Do, * Result.bind("x", () => Result.succeed(2)), * Result.bind("y", ({ x }) => Result.succeed(x + 3)) * ) * console.log(result) * // Output: { _tag: "Success", success: { x: 2, y: 5 }, ... } * ``` * * @see {@link Do} to start the do-notation chain * @see {@link let_ let} for pure computed fields * @see {@link bindTo} to wrap an initial Result into a named field * * @category Do Notation * @since 4.0.0 */ (name: Exclude, f: (a: NoInfer) => Result): (self: Result) => Result<{ [K in N | keyof A]: K extends keyof A ? A[K] : B; }, L1 | L2>; /** * Adds a named field to the do-notation accumulator by running a `Result`-producing * function that receives the current accumulated object. * * - Short-circuits on the first `Failure` * - The field name must not collide with existing keys * - Use {@link let_ let} for pure (non-Result) computed fields * * **Example** (Binding Result values) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.Do, * Result.bind("x", () => Result.succeed(2)), * Result.bind("y", ({ x }) => Result.succeed(x + 3)) * ) * console.log(result) * // Output: { _tag: "Success", success: { x: 2, y: 5 }, ... } * ``` * * @see {@link Do} to start the do-notation chain * @see {@link let_ let} for pure computed fields * @see {@link bindTo} to wrap an initial Result into a named field * * @category Do Notation * @since 4.0.0 */ (self: Result, name: Exclude, f: (a: NoInfer) => Result): Result<{ [K in N | keyof A]: K extends keyof A ? A[K] : B; }, L1 | L2>; }; /** * Wraps the success value of a `Result` into a named field, producing a * `Result>`. This is typically used to start a do-notation * chain from an existing `Result`. * * **Example** (Wrapping a value into a named field) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.succeed(42), * Result.bindTo("answer") * ) * console.log(result) * // Output: { _tag: "Success", success: { answer: 42 }, ... } * ``` * * @see {@link Do} to start from an empty object * @see {@link bind} to add more fields * * @category Do Notation * @since 4.0.0 */ export declare const bindTo: { /** * Wraps the success value of a `Result` into a named field, producing a * `Result>`. This is typically used to start a do-notation * chain from an existing `Result`. * * **Example** (Wrapping a value into a named field) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.succeed(42), * Result.bindTo("answer") * ) * console.log(result) * // Output: { _tag: "Success", success: { answer: 42 }, ... } * ``` * * @see {@link Do} to start from an empty object * @see {@link bind} to add more fields * * @category Do Notation * @since 4.0.0 */ (name: N): (self: Result) => Result, L>; /** * Wraps the success value of a `Result` into a named field, producing a * `Result>`. This is typically used to start a do-notation * chain from an existing `Result`. * * **Example** (Wrapping a value into a named field) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.succeed(42), * Result.bindTo("answer") * ) * console.log(result) * // Output: { _tag: "Success", success: { answer: 42 }, ... } * ``` * * @see {@link Do} to start from an empty object * @see {@link bind} to add more fields * * @category Do Notation * @since 4.0.0 */ (self: Result, name: N): Result, L>; }; declare const let_: { (name: Exclude, f: (r: NoInfer) => B): (self: Result) => Result<{ [K in N | keyof R]: K extends keyof R ? R[K] : B; }, L>; (self: Result, name: Exclude, f: (r: NoInfer) => B): Result<{ [K in N | keyof R]: K extends keyof R ? R[K] : B; }, L>; }; export { /** * Adds a named field to the do-notation accumulator by computing a pure * (non-Result) value from the current accumulated object. * * - Use {@link bind} when the computation returns a `Result` * - The field name must not collide with existing keys * * **Example** (Adding a computed field) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.Do, * Result.bind("x", () => Result.succeed(2)), * Result.bind("y", () => Result.succeed(3)), * Result.let("sum", ({ x, y }) => x + y) * ) * console.log(result) * // Output: { _tag: "Success", success: { x: 2, y: 3, sum: 5 }, ... } * ``` * * @see {@link Do} to start the do-notation chain * @see {@link bind} for Result-producing fields * * @category Do Notation * @since 4.0.0 */ let_ as let }; /** * Transforms `Option>` into `Result, E>`. * * - `None` becomes `Success(None)` * - `Some(Success(a))` becomes `Success(Some(a))` * - `Some(Failure(e))` becomes `Failure(e)` * * **Example** (Transposing an Option of a Result) * * ```ts * import { Option, Result } from "effect" * * const some = Option.some(Result.succeed(42)) * console.log(Result.transposeOption(some)) * // Output: { _tag: "Success", success: { _tag: "Some", value: 42 }, ... } * * const none = Option.none>() * console.log(Result.transposeOption(none)) * // Output: { _tag: "Success", success: { _tag: "None" }, ... } * ``` * * @see {@link transposeMapOption} to map and transpose in one step * * @since 3.14.0 * @category Transposing */ export declare const transposeOption: (self: Option>) => Result, E>; /** * Maps an `Option` value with a `Result`-producing function, then transposes * the structure from `Option>` to `Result, E>`. * * - `None` becomes `Success(None)` (the function is never called) * - `Some(a)` where `f(a)` is `Success(b)` becomes `Success(Some(b))` * - `Some(a)` where `f(a)` is `Failure(e)` becomes `Failure(e)` * * **Example** (Map and transpose in one step) * * ```ts * import { Option, Result } from "effect" * * const parse = (s: string) => * isNaN(Number(s)) * ? Result.fail("not a number" as const) * : Result.succeed(Number(s)) * * console.log(Result.transposeMapOption(Option.some("42"), parse)) * // Output: { _tag: "Success", success: { _tag: "Some", value: 42 }, ... } * * console.log(Result.transposeMapOption(Option.none(), parse)) * // Output: { _tag: "Success", success: { _tag: "None" }, ... } * ``` * * @see {@link transposeOption} when the Option already contains a Result * * @since 3.15.0 * @category Transposing */ export declare const transposeMapOption: ((f: (self: A) => Result) => (self: Option) => Result, E>) & ((self: Option, f: (self: A) => Result) => Result, E>); /** * A pre-built `Result>` that succeeds with `None`. * * - Equivalent to `Result.succeed(Option.none())` but avoids an extra allocation * - Useful with {@link transposeOption} patterns * * **Example** (Using succeedNone) * * ```ts * import { Result } from "effect" * * console.log(Result.isSuccess(Result.succeedNone)) * // Output: true * ``` * * @see {@link succeedSome} for the `Some` counterpart * * @category Constructors * @since 4.0.0 */ export declare const succeedNone: Result, never>; /** * Creates a `Result>` that succeeds with `Some(a)`. * * - Equivalent to `Result.succeed(Option.some(a))` * - Useful with {@link transposeOption} patterns * * **Example** (Wrapping a value in Some inside a Result) * * ```ts * import { Result } from "effect" * * const result = Result.succeedSome(42) * console.log(result) * // Output: { _tag: "Success", success: { _tag: "Some", value: 42 }, ... } * ``` * * @see {@link succeedNone} for the `None` counterpart * * @category Constructors * @since 4.0.0 */ export declare const succeedSome: (a: A) => Result, E>; /** * Runs a side-effect on the success value without altering the `Result`. * * - If the result is a `Success`, calls `f` with the value (return value is ignored) * - If the result is a `Failure`, `f` is not called * - Returns the original `Result` unchanged (same reference) * - Useful for logging, debugging, or performing mutations outside the Result chain * * **Example** (Logging a success value) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.succeed(42), * Result.tap((n) => console.log("Got:", n)) * ) * // Output: "Got: 42" * * console.log(Result.isSuccess(result)) * // Output: true * ``` * * @see {@link map} to transform the success value * * @category Mapping * @since 4.0.0 */ export declare const tap: { /** * Runs a side-effect on the success value without altering the `Result`. * * - If the result is a `Success`, calls `f` with the value (return value is ignored) * - If the result is a `Failure`, `f` is not called * - Returns the original `Result` unchanged (same reference) * - Useful for logging, debugging, or performing mutations outside the Result chain * * **Example** (Logging a success value) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.succeed(42), * Result.tap((n) => console.log("Got:", n)) * ) * // Output: "Got: 42" * * console.log(Result.isSuccess(result)) * // Output: true * ``` * * @see {@link map} to transform the success value * * @category Mapping * @since 4.0.0 */ (f: (a: A) => void): (self: Result) => Result; /** * Runs a side-effect on the success value without altering the `Result`. * * - If the result is a `Success`, calls `f` with the value (return value is ignored) * - If the result is a `Failure`, `f` is not called * - Returns the original `Result` unchanged (same reference) * - Useful for logging, debugging, or performing mutations outside the Result chain * * **Example** (Logging a success value) * * ```ts * import { pipe, Result } from "effect" * * const result = pipe( * Result.succeed(42), * Result.tap((n) => console.log("Got:", n)) * ) * // Output: "Got: 42" * * console.log(Result.isSuccess(result)) * // Output: true * ``` * * @see {@link map} to transform the success value * * @category Mapping * @since 4.0.0 */ (self: Result, f: (a: A) => void): Result; }; //# sourceMappingURL=Result.d.ts.map