1494 lines
43 KiB
TypeScript
1494 lines
43 KiB
TypeScript
/**
|
|
* The `effect/match` module provides a type-safe pattern matching system for
|
|
* TypeScript. Inspired by functional programming, it simplifies conditional
|
|
* logic by replacing verbose if/else or switch statements with a structured and
|
|
* expressive API.
|
|
*
|
|
* This module supports matching against types, values, and discriminated unions
|
|
* while enforcing exhaustiveness checking to ensure all cases are handled.
|
|
*
|
|
* Although pattern matching is not yet a native JavaScript feature,
|
|
* `effect/match` offers a reliable implementation that is available today.
|
|
*
|
|
* **How Pattern Matching Works**
|
|
*
|
|
* Pattern matching follows a structured process:
|
|
*
|
|
* - **Creating a matcher**: Define a `Matcher` that operates on either a
|
|
* specific `Match.type` or `Match.value`.
|
|
*
|
|
* - **Defining patterns**: Use combinators such as `Match.when`, `Match.not`,
|
|
* and `Match.tag` to specify matching conditions.
|
|
*
|
|
* - **Completing the match**: Apply a finalizer such as `Match.exhaustive`,
|
|
* `Match.orElse`, or `Match.option` to determine how unmatched cases should
|
|
* be handled.
|
|
*
|
|
* @since 1.0.0
|
|
*/
|
|
import type * as Either from "./Either.js"
|
|
import * as internal from "./internal/matcher.js"
|
|
import type * as Option from "./Option.js"
|
|
import type { Pipeable } from "./Pipeable.js"
|
|
import * as Predicate from "./Predicate.js"
|
|
import type * as T from "./Types.js"
|
|
import type { Unify } from "./Unify.js"
|
|
|
|
/**
|
|
* @category Symbols
|
|
* @since 1.0.0
|
|
*/
|
|
export const MatcherTypeId: unique symbol = internal.TypeId
|
|
|
|
/**
|
|
* @category Symbols
|
|
* @since 1.0.0
|
|
*/
|
|
export type MatcherTypeId = typeof MatcherTypeId
|
|
|
|
/**
|
|
* Pattern matching follows a structured process:
|
|
*
|
|
* - **Creating a matcher**: Define a `Matcher` that operates on either a
|
|
* specific `Match.type` or `Match.value`.
|
|
*
|
|
* - **Defining patterns**: Use combinators such as `Match.when`, `Match.not`,
|
|
* and `Match.tag` to specify matching conditions.
|
|
*
|
|
* - **Completing the match**: Apply a finalizer such as `Match.exhaustive`,
|
|
* `Match.orElse`, or `Match.option` to determine how unmatched cases should
|
|
* be handled.
|
|
*
|
|
* @example
|
|
* ```ts
|
|
* import { Match } from "effect"
|
|
*
|
|
* // Simulated dynamic input that can be a string or a number
|
|
* const input: string | number = "some input"
|
|
*
|
|
* // ┌─── string
|
|
* // ▼
|
|
* const result = Match.value(input).pipe(
|
|
* // Match if the value is a number
|
|
* Match.when(Match.number, (n) => `number: ${n}`),
|
|
* // Match if the value is a string
|
|
* Match.when(Match.string, (s) => `string: ${s}`),
|
|
* // Ensure all possible cases are covered
|
|
* Match.exhaustive
|
|
* )
|
|
*
|
|
* console.log(result)
|
|
* // Output: "string: some input"
|
|
* ```
|
|
*
|
|
* @category Model
|
|
* @since 1.0.0
|
|
*/
|
|
export type Matcher<Input, Filters, RemainingApplied, Result, Provided, Return = any> =
|
|
| TypeMatcher<Input, Filters, RemainingApplied, Result, Return>
|
|
| ValueMatcher<Input, Filters, RemainingApplied, Result, Provided, Return>
|
|
|
|
/**
|
|
* @category Model
|
|
* @since 1.0.0
|
|
*/
|
|
export interface TypeMatcher<in Input, out Filters, out Remaining, out Result, out Return = any> extends Pipeable {
|
|
readonly _tag: "TypeMatcher"
|
|
readonly [MatcherTypeId]: {
|
|
readonly _input: T.Contravariant<Input>
|
|
readonly _filters: T.Covariant<Filters>
|
|
readonly _remaining: T.Covariant<Remaining>
|
|
readonly _result: T.Covariant<Result>
|
|
readonly _return: T.Covariant<Return>
|
|
}
|
|
readonly cases: ReadonlyArray<Case>
|
|
add<I, R, RA, A>(_case: Case): TypeMatcher<I, R, RA, A>
|
|
}
|
|
|
|
/**
|
|
* @category Model
|
|
* @since 1.0.0
|
|
*/
|
|
export interface ValueMatcher<in Input, out Filters, out Remaining, out Result, out Provided, out Return = any>
|
|
extends Pipeable
|
|
{
|
|
readonly _tag: "ValueMatcher"
|
|
readonly [MatcherTypeId]: {
|
|
readonly _input: T.Contravariant<Input>
|
|
readonly _filters: T.Covariant<Filters>
|
|
readonly _remaining: T.Covariant<Remaining>
|
|
readonly _result: T.Covariant<Result>
|
|
readonly _provided: T.Covariant<Result>
|
|
readonly _return: T.Covariant<Return>
|
|
}
|
|
readonly provided: Provided
|
|
readonly value: Either.Either<Provided, Remaining>
|
|
add<I, R, RA, A, Pr>(_case: Case): ValueMatcher<I, R, RA, A, Pr>
|
|
}
|
|
|
|
/**
|
|
* @category Model
|
|
* @since 1.0.0
|
|
*/
|
|
export type Case = When | Not
|
|
|
|
/**
|
|
* @category Model
|
|
* @since 1.0.0
|
|
*/
|
|
export interface When {
|
|
readonly _tag: "When"
|
|
guard(u: unknown): boolean
|
|
evaluate(input: unknown): any
|
|
}
|
|
|
|
/**
|
|
* @category Model
|
|
* @since 1.0.0
|
|
*/
|
|
export interface Not {
|
|
readonly _tag: "Not"
|
|
guard(u: unknown): boolean
|
|
evaluate(input: unknown): any
|
|
}
|
|
|
|
/**
|
|
* Creates a matcher for a specific type.
|
|
*
|
|
* **Details**
|
|
*
|
|
* This function defines a `Matcher` that operates on a given type, allowing you
|
|
* to specify conditions for handling different cases. Once the matcher is
|
|
* created, you can use pattern-matching functions like {@link when} to define
|
|
* how different values should be processed.
|
|
*
|
|
* **Example** (Matching Numbers and Strings)
|
|
*
|
|
* ```ts
|
|
* import { Match } from "effect"
|
|
*
|
|
* // Create a matcher for values that are either strings or numbers
|
|
* //
|
|
* // ┌─── (u: string | number) => string
|
|
* // ▼
|
|
* const match = Match.type<string | number>().pipe(
|
|
* // Match when the value is a number
|
|
* Match.when(Match.number, (n) => `number: ${n}`),
|
|
* // Match when the value is a string
|
|
* Match.when(Match.string, (s) => `string: ${s}`),
|
|
* // Ensure all possible cases are handled
|
|
* Match.exhaustive
|
|
* )
|
|
*
|
|
* console.log(match(0))
|
|
* // Output: "number: 0"
|
|
*
|
|
* console.log(match("hello"))
|
|
* // Output: "string: hello"
|
|
* ```
|
|
*
|
|
* @see {@link value} for creating a matcher from a specific value.
|
|
*
|
|
* @category Creating a matcher
|
|
* @since 1.0.0
|
|
*/
|
|
export const type: <I>() => Matcher<I, Types.Without<never>, I, never, never> = internal.type
|
|
|
|
/**
|
|
* Creates a matcher from a specific value.
|
|
*
|
|
* **Details**
|
|
*
|
|
* This function allows you to define a `Matcher` directly from a given value,
|
|
* rather than from a type. This is useful when working with known values,
|
|
* enabling structured pattern matching on objects, primitives, or any data
|
|
* structure.
|
|
*
|
|
* Once the matcher is created, you can use pattern-matching functions like
|
|
* {@link when} to define how different cases should be handled.
|
|
*
|
|
* **Example** (Matching an Object by Property)
|
|
*
|
|
* ```ts
|
|
* import { Match } from "effect"
|
|
*
|
|
* const input = { name: "John", age: 30 }
|
|
*
|
|
* // Create a matcher for the specific object
|
|
* const result = Match.value(input).pipe(
|
|
* // Match when the 'name' property is "John"
|
|
* Match.when(
|
|
* { name: "John" },
|
|
* (user) => `${user.name} is ${user.age} years old`
|
|
* ),
|
|
* // Provide a fallback if no match is found
|
|
* Match.orElse(() => "Oh, not John")
|
|
* )
|
|
*
|
|
* console.log(result)
|
|
* // Output: "John is 30 years old"
|
|
* ```
|
|
*
|
|
* @see {@link type} for creating a matcher from a specific type.
|
|
*
|
|
* @category Creating a matcher
|
|
* @since 1.0.0
|
|
*/
|
|
export const value: <const I>(
|
|
i: I
|
|
) => Matcher<I, Types.Without<never>, I, never, I> = internal.value
|
|
|
|
/**
|
|
* @category Creating a matcher
|
|
* @since 1.0.0
|
|
*/
|
|
export const valueTags: {
|
|
/**
|
|
* @category Creating a matcher
|
|
* @since 1.0.0
|
|
*/
|
|
<
|
|
const I,
|
|
P extends
|
|
& { readonly [Tag in Types.Tags<"_tag", I> & string]: (_: Extract<I, { readonly _tag: Tag }>) => any }
|
|
& { readonly [Tag in Exclude<keyof P, Types.Tags<"_tag", I>>]: never }
|
|
>(fields: P): (input: I) => Unify<ReturnType<P[keyof P]>>
|
|
/**
|
|
* @category Creating a matcher
|
|
* @since 1.0.0
|
|
*/
|
|
<
|
|
const I,
|
|
P extends
|
|
& { readonly [Tag in Types.Tags<"_tag", I> & string]: (_: Extract<I, { readonly _tag: Tag }>) => any }
|
|
& { readonly [Tag in Exclude<keyof P, Types.Tags<"_tag", I>>]: never }
|
|
>(input: I, fields: P): Unify<ReturnType<P[keyof P]>>
|
|
} = internal.valueTags
|
|
|
|
/**
|
|
* @category Creating a matcher
|
|
* @since 1.0.0
|
|
*/
|
|
export const typeTags: {
|
|
/**
|
|
* @category Creating a matcher
|
|
* @since 1.0.0
|
|
*/
|
|
<I, Ret>(): <
|
|
P extends
|
|
& {
|
|
readonly [Tag in Types.Tags<"_tag", I> & string]: (
|
|
_: Extract<I, { readonly _tag: Tag }>
|
|
) => Ret
|
|
}
|
|
& { readonly [Tag in Exclude<keyof P, Types.Tags<"_tag", I>>]: never }
|
|
>(fields: P) => (input: I) => Ret
|
|
/**
|
|
* @category Creating a matcher
|
|
* @since 1.0.0
|
|
*/
|
|
<I>(): <
|
|
P extends
|
|
& {
|
|
readonly [Tag in Types.Tags<"_tag", I> & string]: (
|
|
_: Extract<I, { readonly _tag: Tag }>
|
|
) => any
|
|
}
|
|
& { readonly [Tag in Exclude<keyof P, Types.Tags<"_tag", I>>]: never }
|
|
>(fields: P) => (input: I) => Unify<ReturnType<P[keyof P]>>
|
|
} = internal.typeTags
|
|
|
|
/**
|
|
* Ensures that all branches of a matcher return a specific type.
|
|
*
|
|
* **Details**
|
|
*
|
|
* This function enforces a consistent return type across all pattern-matching
|
|
* branches. By specifying a return type, TypeScript will check that every
|
|
* matching condition produces a value of the expected type.
|
|
*
|
|
* **Important:** This function must be the first step in the matcher pipeline.
|
|
* If used later, TypeScript will not enforce type consistency correctly.
|
|
*
|
|
* **Example** (Validating Return Type Consistency)
|
|
*
|
|
* ```ts
|
|
* import { Match } from "effect"
|
|
*
|
|
* const match = Match.type<{ a: number } | { b: string }>().pipe(
|
|
* // Ensure all branches return a string
|
|
* Match.withReturnType<string>(),
|
|
* // ❌ Type error: 'number' is not assignable to type 'string'
|
|
* // @ts-expect-error
|
|
* Match.when({ a: Match.number }, (_) => _.a),
|
|
* // ✅ Correct: returns a string
|
|
* Match.when({ b: Match.string }, (_) => _.b),
|
|
* Match.exhaustive
|
|
* )
|
|
* ```
|
|
*
|
|
* @since 1.0.0
|
|
*/
|
|
export const withReturnType: <Ret>() => <I, F, R, A, Pr, _>(
|
|
self: Matcher<I, F, R, A, Pr, _>
|
|
) => [Ret] extends [[A] extends [never] ? any : A] ? Matcher<I, F, R, A, Pr, Ret>
|
|
: "withReturnType constraint does not extend Result type" = internal.withReturnType
|
|
|
|
/**
|
|
* Defines a condition for matching values.
|
|
*
|
|
* **Details**
|
|
*
|
|
* This function enables pattern matching by checking whether a given value
|
|
* satisfies a condition. It supports both direct value comparisons and
|
|
* predicate functions. If the condition is met, the associated function is
|
|
* executed.
|
|
*
|
|
* This function is useful when defining matchers that need to check for
|
|
* specific values or apply logical conditions to determine a match. It works
|
|
* well with structured objects and primitive types.
|
|
*
|
|
* **Example** (Matching with Values and Predicates)
|
|
*
|
|
* ```ts
|
|
* import { Match } from "effect"
|
|
*
|
|
* // Create a matcher for objects with an "age" property
|
|
* const match = Match.type<{ age: number }>().pipe(
|
|
* // Match when age is greater than 18
|
|
* Match.when({ age: (age) => age > 18 }, (user) => `Age: ${user.age}`),
|
|
* // Match when age is exactly 18
|
|
* Match.when({ age: 18 }, () => "You can vote"),
|
|
* // Fallback case for all other ages
|
|
* Match.orElse((user) => `${user.age} is too young`)
|
|
* )
|
|
*
|
|
* console.log(match({ age: 20 }))
|
|
* // Output: "Age: 20"
|
|
*
|
|
* console.log(match({ age: 18 }))
|
|
* // Output: "You can vote"
|
|
*
|
|
* console.log(match({ age: 4 }))
|
|
* // Output: "4 is too young"
|
|
* ```
|
|
*
|
|
* @see {@link whenOr} Use this when multiple patterns should match in a single
|
|
* condition.
|
|
* @see {@link whenAnd} Use this when a value must match all provided patterns.
|
|
* @see {@link orElse} Provides a fallback when no patterns match.
|
|
*
|
|
* @category Defining patterns
|
|
* @since 1.0.0
|
|
*/
|
|
export const when: <
|
|
R,
|
|
const P extends Types.PatternPrimitive<R> | Types.PatternBase<R>,
|
|
Ret,
|
|
Fn extends (_: Types.WhenMatch<R, P>) => Ret
|
|
>(
|
|
pattern: P,
|
|
f: Fn
|
|
) => <I, F, A, Pr>(
|
|
self: Matcher<I, F, R, A, Pr, Ret>
|
|
) => Matcher<
|
|
I,
|
|
Types.AddWithout<F, Types.PForExclude<P>>,
|
|
Types.ApplyFilters<I, Types.AddWithout<F, Types.PForExclude<P>>>,
|
|
A | ReturnType<Fn>,
|
|
Pr,
|
|
Ret
|
|
> = internal.when
|
|
|
|
/**
|
|
* Matches one of multiple patterns in a single condition.
|
|
*
|
|
* **Details**
|
|
*
|
|
* This function allows defining a condition where a value matches any of the
|
|
* provided patterns. If a match is found, the associated function is executed.
|
|
* It simplifies cases where multiple patterns share the same handling logic.
|
|
*
|
|
* Unlike {@link when}, which requires separate conditions for each pattern,
|
|
* this function enables combining them into a single statement, making the
|
|
* matcher more concise.
|
|
*
|
|
* @example
|
|
* ```ts
|
|
* import { Match } from "effect"
|
|
*
|
|
* type ErrorType =
|
|
* | { readonly _tag: "NetworkError"; readonly message: string }
|
|
* | { readonly _tag: "TimeoutError"; readonly duration: number }
|
|
* | { readonly _tag: "ValidationError"; readonly field: string }
|
|
*
|
|
* const handleError = Match.type<ErrorType>().pipe(
|
|
* Match.whenOr(
|
|
* { _tag: "NetworkError" },
|
|
* { _tag: "TimeoutError" },
|
|
* () => "Retry the request"
|
|
* ),
|
|
* Match.when({ _tag: "ValidationError" }, (_) => `Invalid field: ${_.field}`),
|
|
* Match.exhaustive
|
|
* )
|
|
*
|
|
* console.log(handleError({ _tag: "NetworkError", message: "No connection" }))
|
|
* // Output: "Retry the request"
|
|
*
|
|
* console.log(handleError({ _tag: "ValidationError", field: "email" }))
|
|
* // Output: "Invalid field: email"
|
|
* ```
|
|
*
|
|
* @category Defining patterns
|
|
* @since 1.0.0
|
|
*/
|
|
export const whenOr: <
|
|
R,
|
|
const P extends ReadonlyArray<Types.PatternPrimitive<R> | Types.PatternBase<R>>,
|
|
Ret,
|
|
Fn extends (_: Types.WhenMatch<R, P[number]>) => Ret
|
|
>(
|
|
...args: [...patterns: P, f: Fn]
|
|
) => <I, F, A, Pr>(
|
|
self: Matcher<I, F, R, A, Pr, Ret>
|
|
) => Matcher<
|
|
I,
|
|
Types.AddWithout<F, Types.PForExclude<P[number]>>,
|
|
Types.ApplyFilters<I, Types.AddWithout<F, Types.PForExclude<P[number]>>>,
|
|
A | ReturnType<Fn>,
|
|
Pr,
|
|
Ret
|
|
> = internal.whenOr
|
|
|
|
/**
|
|
* Matches a value that satisfies all provided patterns.
|
|
*
|
|
* **Details**
|
|
*
|
|
* This function allows defining a condition where a value must match all the
|
|
* given patterns simultaneously. If the value satisfies every pattern, the
|
|
* associated function is executed.
|
|
*
|
|
* Unlike {@link when}, which matches a single pattern at a time, this function
|
|
* ensures that multiple conditions are met before executing the callback. It is
|
|
* useful when checking for values that need to fulfill multiple criteria at
|
|
* once.
|
|
*
|
|
* @example
|
|
* ```ts
|
|
* import { Match } from "effect"
|
|
*
|
|
* type User = { readonly age: number; readonly role: "admin" | "user" }
|
|
*
|
|
* const checkUser = Match.type<User>().pipe(
|
|
* Match.whenAnd(
|
|
* { age: (n) => n >= 18 },
|
|
* { role: "admin" },
|
|
* () => "Admin access granted"
|
|
* ),
|
|
* Match.orElse(() => "Access denied")
|
|
* )
|
|
*
|
|
* console.log(checkUser({ age: 20, role: "admin" }))
|
|
* // Output: "Admin access granted"
|
|
*
|
|
* console.log(checkUser({ age: 20, role: "user" }))
|
|
* // Output: "Access denied"
|
|
* ```
|
|
*
|
|
* @category Defining patterns
|
|
* @since 1.0.0
|
|
*/
|
|
export const whenAnd: <
|
|
R,
|
|
const P extends ReadonlyArray<Types.PatternPrimitive<R> | Types.PatternBase<R>>,
|
|
Ret,
|
|
Fn extends (_: Types.WhenMatch<R, T.UnionToIntersection<P[number]>>) => Ret
|
|
>(
|
|
...args: [...patterns: P, f: Fn]
|
|
) => <I, F, A, Pr>(
|
|
self: Matcher<I, F, R, A, Pr, Ret>
|
|
) => Matcher<
|
|
I,
|
|
Types.AddWithout<F, Types.PForExclude<T.UnionToIntersection<P[number]>>>,
|
|
Types.ApplyFilters<I, Types.AddWithout<F, Types.PForExclude<T.UnionToIntersection<P[number]>>>>,
|
|
A | ReturnType<Fn>,
|
|
Pr
|
|
> = internal.whenAnd
|
|
|
|
/**
|
|
* Matches values based on a specified discriminant field.
|
|
*
|
|
* **Details**
|
|
*
|
|
* This function is used to define pattern matching on objects that follow a
|
|
* **discriminated union** structure, where a specific field (e.g., `type`,
|
|
* `kind`, `_tag`) determines the variant of the object. It allows matching
|
|
* multiple values of the discriminant and provides a function to handle the
|
|
* matched cases.
|
|
*
|
|
* @example
|
|
* ```ts
|
|
* import { Match, pipe } from "effect"
|
|
*
|
|
* const match = pipe(
|
|
* Match.type<{ type: "A"; a: string } | { type: "B"; b: number } | { type: "C"; c: boolean }>(),
|
|
* Match.discriminator("type")("A", "B", (_) => `A or B: ${_.type}`),
|
|
* Match.discriminator("type")("C", (_) => `C(${_.c})`),
|
|
* Match.exhaustive
|
|
* )
|
|
* ```
|
|
*
|
|
* @category Defining patterns
|
|
* @since 1.0.0
|
|
*/
|
|
export const discriminator: <D extends string>(
|
|
field: D
|
|
) => <R, P extends Types.Tags<D, R> & string, Ret, Fn extends (_: Extract<R, Record<D, P>>) => Ret>(
|
|
...pattern: [first: P, ...values: Array<P>, f: Fn]
|
|
) => <I, F, A, Pr>(
|
|
self: Matcher<I, F, R, A, Pr, Ret>
|
|
) => Matcher<
|
|
I,
|
|
Types.AddWithout<F, Extract<R, Record<D, P>>>,
|
|
Types.ApplyFilters<I, Types.AddWithout<F, Extract<R, Record<D, P>>>>,
|
|
A | ReturnType<Fn>,
|
|
Pr,
|
|
Ret
|
|
> = internal.discriminator
|
|
|
|
/**
|
|
* Matches values where a specified field starts with a given prefix.
|
|
*
|
|
* **Details**
|
|
*
|
|
* This function is useful for working with discriminated unions where the
|
|
* discriminant field follows a hierarchical or namespaced structure. It allows
|
|
* you to match values based on whether the specified field starts with a given
|
|
* prefix, making it easier to handle grouped cases.
|
|
*
|
|
* Instead of checking for exact matches, this function lets you match values
|
|
* that share a common prefix. For example, if your discriminant field contains
|
|
* hierarchical names like `"A"`, `"A.A"`, and `"B"`, you can match all values
|
|
* starting with `"A"` using a single rule.
|
|
*
|
|
* @example
|
|
* ```ts
|
|
* import { Match, pipe } from "effect"
|
|
*
|
|
* const match = pipe(
|
|
* Match.type<{ type: "A" } | { type: "B" } | { type: "A.A" } | {}>(),
|
|
* Match.discriminatorStartsWith("type")("A", (_) => 1 as const),
|
|
* Match.discriminatorStartsWith("type")("B", (_) => 2 as const),
|
|
* Match.orElse((_) => 3 as const)
|
|
* )
|
|
*
|
|
* console.log(match({ type: "A" })) // 1
|
|
* console.log(match({ type: "B" })) // 2
|
|
* console.log(match({ type: "A.A" })) // 1
|
|
* ```
|
|
*
|
|
* @category Defining patterns
|
|
* @since 1.0.0
|
|
*/
|
|
export const discriminatorStartsWith: <D extends string>(
|
|
field: D
|
|
) => <R, P extends string, Ret, Fn extends (_: Extract<R, Record<D, `${P}${string}`>>) => Ret>(
|
|
pattern: P,
|
|
f: Fn
|
|
) => <I, F, A, Pr>(
|
|
self: Matcher<I, F, R, A, Pr, Ret>
|
|
) => Matcher<
|
|
I,
|
|
Types.AddWithout<F, Extract<R, Record<D, `${P}${string}`>>>,
|
|
Types.ApplyFilters<I, Types.AddWithout<F, Extract<R, Record<D, `${P}${string}`>>>>,
|
|
A | ReturnType<Fn>,
|
|
Pr,
|
|
Ret
|
|
> = internal.discriminatorStartsWith
|
|
|
|
/**
|
|
* Matches values based on a field that serves as a discriminator, mapping each
|
|
* possible value to a corresponding handler.
|
|
*
|
|
* **Details**
|
|
*
|
|
* This function simplifies working with discriminated unions by letting you
|
|
* define a set of handlers for each possible value of a given field. Instead of
|
|
* chaining multiple calls to {@link discriminator}, this function allows
|
|
* defining all possible cases at once using an object where the keys are the
|
|
* possible values of the field, and the values are the corresponding handler
|
|
* functions.
|
|
*
|
|
* @example
|
|
* ```ts
|
|
* import { Match, pipe } from "effect"
|
|
*
|
|
* const match = pipe(
|
|
* Match.type<{ type: "A"; a: string } | { type: "B"; b: number } | { type: "C"; c: boolean }>(),
|
|
* Match.discriminators("type")({
|
|
* A: (a) => a.a,
|
|
* B: (b) => b.b,
|
|
* C: (c) => c.c
|
|
* }),
|
|
* Match.exhaustive
|
|
* )
|
|
* ```
|
|
*
|
|
* @category Defining patterns
|
|
* @since 1.0.0
|
|
*/
|
|
export const discriminators: <D extends string>(
|
|
field: D
|
|
) => <
|
|
R,
|
|
Ret,
|
|
P extends
|
|
& { readonly [Tag in Types.Tags<D, R> & string]?: ((_: Extract<R, Record<D, Tag>>) => Ret) | undefined }
|
|
& { readonly [Tag in Exclude<keyof P, Types.Tags<D, R>>]: never }
|
|
>(
|
|
fields: P
|
|
) => <I, F, A, Pr>(
|
|
self: Matcher<I, F, R, A, Pr, Ret>
|
|
) => Matcher<
|
|
I,
|
|
Types.AddWithout<F, Extract<R, Record<D, keyof P>>>,
|
|
Types.ApplyFilters<I, Types.AddWithout<F, Extract<R, Record<D, keyof P>>>>,
|
|
A | ReturnType<P[keyof P] & {}>,
|
|
Pr,
|
|
Ret
|
|
> = internal.discriminators
|
|
|
|
/**
|
|
* Matches values based on a discriminator field and **ensures all cases are
|
|
* handled**.
|
|
*
|
|
* **Details*+
|
|
*
|
|
* This function is similar to {@link discriminators}, but **requires that all
|
|
* possible cases** are explicitly handled. It is useful when working with
|
|
* discriminated unions, where a specific field (e.g., `"type"`) determines the
|
|
* shape of an object. Each possible value of the field must have a
|
|
* corresponding handler, ensuring **exhaustiveness checking** at compile time.
|
|
*
|
|
* This function **does not require** `Match.exhaustive` at the end of the
|
|
* pipeline because it enforces exhaustiveness by design.
|
|
*
|
|
* @example
|
|
* ```ts
|
|
* import { Match, pipe } from "effect"
|
|
*
|
|
* const match = pipe(
|
|
* Match.type<{ type: "A"; a: string } | { type: "B"; b: number } | { type: "C"; c: boolean }>(),
|
|
* Match.discriminatorsExhaustive("type")({
|
|
* A: (a) => a.a,
|
|
* B: (b) => b.b,
|
|
* C: (c) => c.c
|
|
* })
|
|
* )
|
|
* ```
|
|
*
|
|
* @category Defining patterns
|
|
* @since 1.0.0
|
|
*/
|
|
export const discriminatorsExhaustive: <D extends string>(
|
|
field: D
|
|
) => <
|
|
R,
|
|
Ret,
|
|
P extends
|
|
& { readonly [Tag in Types.Tags<D, R> & string]: (_: Extract<R, Record<D, Tag>>) => Ret }
|
|
& { readonly [Tag in Exclude<keyof P, Types.Tags<D, R>>]: never }
|
|
>(
|
|
fields: P
|
|
) => <I, F, A, Pr>(
|
|
self: Matcher<I, F, R, A, Pr, Ret>
|
|
) => [Pr] extends [never] ? (u: I) => Unify<A | ReturnType<P[keyof P]>> : Unify<A | ReturnType<P[keyof P]>> =
|
|
internal.discriminatorsExhaustive
|
|
|
|
/**
|
|
* The `Match.tag` function allows pattern matching based on the `_tag` field in
|
|
* a [Discriminated Union](https://www.typescriptlang.org/docs/handbook/typescript-in-5-minutes-func.html#discriminated-unions).
|
|
* You can specify multiple tags to match within a single pattern.
|
|
*
|
|
* **Note**
|
|
*
|
|
* The `Match.tag` function relies on the convention within the Effect ecosystem
|
|
* of naming the tag field as `"_tag"`. Ensure that your discriminated unions
|
|
* follow this naming convention for proper functionality.
|
|
*
|
|
* **Example** (Matching a Discriminated Union by Tag)
|
|
*
|
|
* ```ts
|
|
* import { Match } from "effect"
|
|
*
|
|
* type Event =
|
|
* | { readonly _tag: "fetch" }
|
|
* | { readonly _tag: "success"; readonly data: string }
|
|
* | { readonly _tag: "error"; readonly error: Error }
|
|
* | { readonly _tag: "cancel" }
|
|
*
|
|
* // Create a Matcher for Either<number, string>
|
|
* const match = Match.type<Event>().pipe(
|
|
* // Match either "fetch" or "success"
|
|
* Match.tag("fetch", "success", () => `Ok!`),
|
|
* // Match "error" and extract the error message
|
|
* Match.tag("error", (event) => `Error: ${event.error.message}`),
|
|
* // Match "cancel"
|
|
* Match.tag("cancel", () => "Cancelled"),
|
|
* Match.exhaustive
|
|
* )
|
|
*
|
|
* console.log(match({ _tag: "success", data: "Hello" }))
|
|
* // Output: "Ok!"
|
|
*
|
|
* console.log(match({ _tag: "error", error: new Error("Oops!") }))
|
|
* // Output: "Error: Oops!"
|
|
* ```
|
|
*
|
|
* @category Defining patterns
|
|
* @since 1.0.0
|
|
*/
|
|
export const tag: <
|
|
R,
|
|
P extends Types.Tags<"_tag", R> & string,
|
|
Ret,
|
|
Fn extends (_: Extract<R, Record<"_tag", P>>) => Ret
|
|
>(
|
|
...pattern: [first: P, ...values: Array<P>, f: Fn]
|
|
) => <I, F, A, Pr>(
|
|
self: Matcher<I, F, R, A, Pr, Ret>
|
|
) => Matcher<
|
|
I,
|
|
Types.AddWithout<F, Extract<R, Record<"_tag", P>>>,
|
|
Types.ApplyFilters<I, Types.AddWithout<F, Extract<R, Record<"_tag", P>>>>,
|
|
ReturnType<Fn> | A,
|
|
Pr,
|
|
Ret
|
|
> = internal.tag
|
|
|
|
/**
|
|
* Matches values where the `_tag` field starts with a given prefix.
|
|
*
|
|
* **Details**
|
|
*
|
|
* This function allows you to match on values in a **discriminated union**
|
|
* based on whether the `_tag` field starts with a specified prefix. It is
|
|
* useful for handling hierarchical or namespaced tags, where multiple related
|
|
* cases share a common prefix.
|
|
*
|
|
* @example
|
|
* ```ts
|
|
* import { Match, pipe } from "effect"
|
|
*
|
|
* const match = pipe(
|
|
* Match.type<{ _tag: "A" } | { _tag: "B" } | { _tag: "A.A" } | {}>(),
|
|
* Match.tagStartsWith("A", (_) => 1 as const),
|
|
* Match.tagStartsWith("B", (_) => 2 as const),
|
|
* Match.orElse((_) => 3 as const)
|
|
* )
|
|
*
|
|
* console.log(match({ _tag: "A" })) // 1
|
|
* console.log(match({ _tag: "B" })) // 2
|
|
* console.log(match({ _tag: "A.A" })) // 1
|
|
* ```
|
|
*
|
|
* @category Defining patterns
|
|
* @since 1.0.0
|
|
*/
|
|
export const tagStartsWith: <
|
|
R,
|
|
P extends string,
|
|
Ret,
|
|
Fn extends (_: Extract<R, Record<"_tag", `${P}${string}`>>) => Ret
|
|
>(
|
|
pattern: P,
|
|
f: Fn
|
|
) => <I, F, A, Pr>(
|
|
self: Matcher<I, F, R, A, Pr, Ret>
|
|
) => Matcher<
|
|
I,
|
|
Types.AddWithout<F, Extract<R, Record<"_tag", `${P}${string}`>>>,
|
|
Types.ApplyFilters<I, Types.AddWithout<F, Extract<R, Record<"_tag", `${P}${string}`>>>>,
|
|
ReturnType<Fn> | A,
|
|
Pr,
|
|
Ret
|
|
> = internal.tagStartsWith
|
|
|
|
/**
|
|
* Matches values based on their `_tag` field, mapping each tag to a
|
|
* corresponding handler.
|
|
*
|
|
* **Details**
|
|
*
|
|
* This function provides a way to handle discriminated unions by mapping `_tag`
|
|
* values to specific functions. Each handler receives the matched value and
|
|
* returns a transformed result. If all possible tags are handled, you can
|
|
* enforce exhaustiveness using `Match.exhaustive` to ensure no case is missed.
|
|
*
|
|
* @example
|
|
* ```ts
|
|
* import { Match, pipe } from "effect"
|
|
*
|
|
* const match = pipe(
|
|
* Match.type<{ _tag: "A"; a: string } | { _tag: "B"; b: number } | { _tag: "C"; c: boolean }>(),
|
|
* Match.tags({
|
|
* A: (a) => a.a,
|
|
* B: (b) => b.b,
|
|
* C: (c) => c.c
|
|
* }),
|
|
* Match.exhaustive
|
|
* )
|
|
* ```
|
|
*
|
|
* @category Defining patterns
|
|
* @since 1.0.0
|
|
*/
|
|
export const tags: <
|
|
R,
|
|
Ret,
|
|
P extends
|
|
& { readonly [Tag in Types.Tags<"_tag", R> & string]?: ((_: Extract<R, Record<"_tag", Tag>>) => Ret) | undefined }
|
|
& { readonly [Tag in Exclude<keyof P, Types.Tags<"_tag", R>>]: never }
|
|
>(
|
|
fields: P
|
|
) => <I, F, A, Pr>(
|
|
self: Matcher<I, F, R, A, Pr, Ret>
|
|
) => Matcher<
|
|
I,
|
|
Types.AddWithout<F, Extract<R, Record<"_tag", keyof P>>>,
|
|
Types.ApplyFilters<I, Types.AddWithout<F, Extract<R, Record<"_tag", keyof P>>>>,
|
|
A | ReturnType<P[keyof P] & {}>,
|
|
Pr,
|
|
Ret
|
|
> = internal.tags
|
|
|
|
/**
|
|
* Matches values based on their `_tag` field and requires handling of all
|
|
* possible cases.
|
|
*
|
|
* **Details**
|
|
*
|
|
* This function is designed for **discriminated unions** where every possible
|
|
* `_tag` value must have a corresponding handler. Unlike {@link tags}, this
|
|
* function ensures **exhaustiveness**, meaning all cases must be explicitly
|
|
* handled. If a `_tag` value is missing from the mapping, TypeScript will
|
|
* report an error.
|
|
*
|
|
* @example
|
|
* ```ts
|
|
* import { Match, pipe } from "effect"
|
|
*
|
|
* const match = pipe(
|
|
* Match.type<{ _tag: "A"; a: string } | { _tag: "B"; b: number } | { _tag: "C"; c: boolean }>(),
|
|
* Match.tagsExhaustive({
|
|
* A: (a) => a.a,
|
|
* B: (b) => b.b,
|
|
* C: (c) => c.c
|
|
* })
|
|
* )
|
|
* ```
|
|
*
|
|
* @category Defining patterns
|
|
* @since 1.0.0
|
|
*/
|
|
export const tagsExhaustive: <
|
|
R,
|
|
Ret,
|
|
P extends
|
|
& { readonly [Tag in Types.Tags<"_tag", R> & string]: (_: Extract<R, Record<"_tag", Tag>>) => Ret }
|
|
& { readonly [Tag in Exclude<keyof P, Types.Tags<"_tag", R>>]: never }
|
|
>(
|
|
fields: P
|
|
) => <I, F, A, Pr>(
|
|
self: Matcher<I, F, R, A, Pr, Ret>
|
|
) => [Pr] extends [never] ? (u: I) => Unify<A | ReturnType<P[keyof P]>> : Unify<A | ReturnType<P[keyof P]>> =
|
|
internal.tagsExhaustive
|
|
|
|
/**
|
|
* Excludes a specific value from matching while allowing all others.
|
|
*
|
|
* **Details**
|
|
*
|
|
* This function is useful when you need to **handle all values except one or
|
|
* more specific cases**. Instead of listing all possible matches manually, this
|
|
* function simplifies the logic by allowing you to specify values to exclude.
|
|
* Any excluded value will bypass the provided function and continue matching
|
|
* through other cases.
|
|
*
|
|
* **Example** (Ignoring a Specific Value)
|
|
*
|
|
* ```ts
|
|
* import { Match } from "effect"
|
|
*
|
|
* // Create a matcher for string or number values
|
|
* const match = Match.type<string | number>().pipe(
|
|
* // Match any value except "hi", returning "ok"
|
|
* Match.not("hi", () => "ok"),
|
|
* // Fallback case for when the value is "hi"
|
|
* Match.orElse(() => "fallback")
|
|
* )
|
|
*
|
|
* console.log(match("hello"))
|
|
* // Output: "ok"
|
|
*
|
|
* console.log(match("hi"))
|
|
* // Output: "fallback"
|
|
* ```
|
|
*
|
|
* @category Defining patterns
|
|
* @since 1.0.0
|
|
*/
|
|
export const not: <
|
|
R,
|
|
const P extends Types.PatternPrimitive<R> | Types.PatternBase<R>,
|
|
Ret,
|
|
Fn extends (_: Types.NotMatch<R, P>) => Ret
|
|
>(
|
|
pattern: P,
|
|
f: Fn
|
|
) => <I, F, A, Pr>(
|
|
self: Matcher<I, F, R, A, Pr, Ret>
|
|
) => Matcher<
|
|
I,
|
|
Types.AddOnly<F, Types.WhenMatch<R, P>>,
|
|
Types.ApplyFilters<I, Types.AddOnly<F, Types.WhenMatch<R, P>>>,
|
|
A | ReturnType<Fn>,
|
|
Pr,
|
|
Ret
|
|
> = internal.not
|
|
|
|
/**
|
|
* Matches non-empty strings.
|
|
*
|
|
* @category Predicates
|
|
* @since 1.0.0
|
|
*/
|
|
export const nonEmptyString: SafeRefinement<string, never> = internal.nonEmptyString
|
|
|
|
/**
|
|
* Matches a specific set of literal values (e.g., `Match.is("a", 42, true)`).
|
|
*
|
|
* @category Predicates
|
|
* @since 1.0.0
|
|
*/
|
|
export const is: <
|
|
Literals extends ReadonlyArray<string | number | bigint | boolean | null>
|
|
>(...literals: Literals) => SafeRefinement<Literals[number]> = internal.is
|
|
|
|
/**
|
|
* Matches values of type `string`.
|
|
*
|
|
* @category Predicates
|
|
* @since 1.0.0
|
|
*/
|
|
export const string: Predicate.Refinement<unknown, string> = Predicate.isString
|
|
|
|
/**
|
|
* Matches values of type `number`.
|
|
*
|
|
* @category Predicates
|
|
* @since 1.0.0
|
|
*/
|
|
export const number: Predicate.Refinement<unknown, number> = Predicate.isNumber
|
|
|
|
/**
|
|
* Matches any value without restrictions.
|
|
*
|
|
* @category Predicates
|
|
* @since 1.0.0
|
|
*/
|
|
export const any: SafeRefinement<unknown, any> = internal.any
|
|
|
|
/**
|
|
* Matches any defined (non-null and non-undefined) value.
|
|
*
|
|
* @category Predicates
|
|
* @since 1.0.0
|
|
*/
|
|
export const defined: <A>(u: A) => u is A & {} = internal.defined
|
|
|
|
/**
|
|
* Matches values of type `boolean`.
|
|
*
|
|
* @category Predicates
|
|
* @since 1.0.0
|
|
*/
|
|
export const boolean: Predicate.Refinement<unknown, boolean> = Predicate.isBoolean
|
|
|
|
const _undefined: Predicate.Refinement<unknown, undefined> = Predicate.isUndefined
|
|
export {
|
|
/**
|
|
* Matches the value `undefined`.
|
|
*
|
|
* @category Predicates
|
|
* @since 1.0.0
|
|
*/
|
|
_undefined as undefined
|
|
}
|
|
|
|
const _null: Predicate.Refinement<unknown, null> = Predicate.isNull
|
|
export {
|
|
/**
|
|
* Matches the value `null`.
|
|
*
|
|
* @category Predicates
|
|
* @since 1.0.0
|
|
*/
|
|
_null as null
|
|
}
|
|
|
|
/**
|
|
* Matches values of type `bigint`.
|
|
*
|
|
* @category Predicates
|
|
* @since 1.0.0
|
|
*/
|
|
export const bigint: Predicate.Refinement<unknown, bigint> = Predicate.isBigInt
|
|
|
|
/**
|
|
* Matches values of type `symbol`.
|
|
*
|
|
* @category Predicates
|
|
* @since 1.0.0
|
|
*/
|
|
export const symbol: Predicate.Refinement<unknown, symbol> = Predicate.isSymbol
|
|
|
|
/**
|
|
* Matches values that are instances of `Date`.
|
|
*
|
|
* @category Predicates
|
|
* @since 1.0.0
|
|
*/
|
|
export const date: Predicate.Refinement<unknown, Date> = Predicate.isDate
|
|
|
|
/**
|
|
* Matches objects where keys are `string` or `symbol` and values are `unknown`.
|
|
*
|
|
* @category Predicates
|
|
* @since 1.0.0
|
|
*/
|
|
export const record: Predicate.Refinement<unknown, { [x: string | symbol]: unknown }> = Predicate.isRecord
|
|
|
|
/**
|
|
* Matches instances of a given class.
|
|
*
|
|
* @category Predicates
|
|
* @since 1.0.0
|
|
*/
|
|
export const instanceOf: <A extends abstract new(...args: any) => any>(
|
|
constructor: A
|
|
) => SafeRefinement<InstanceType<A>, never> = internal.instanceOf
|
|
|
|
/**
|
|
* @category Predicates
|
|
* @since 1.0.0
|
|
*/
|
|
export const instanceOfUnsafe: <A extends abstract new(...args: any) => any>(
|
|
constructor: A
|
|
) => SafeRefinement<InstanceType<A>, InstanceType<A>> = internal.instanceOf
|
|
|
|
/**
|
|
* Provides a fallback value when no patterns match.
|
|
*
|
|
* **Details**
|
|
*
|
|
* This function ensures that a matcher always returns a valid result, even if
|
|
* no defined patterns match. It acts as a default case, similar to the
|
|
* `default` clause in a `switch` statement or the final `else` in an `if-else`
|
|
* chain.
|
|
*
|
|
* **Example** (Providing a Default Value When No Patterns Match)
|
|
*
|
|
* ```ts
|
|
* import { Match } from "effect"
|
|
*
|
|
* // Create a matcher for string or number values
|
|
* const match = Match.type<string | number>().pipe(
|
|
* // Match when the value is "a"
|
|
* Match.when("a", () => "ok"),
|
|
* // Fallback when no patterns match
|
|
* Match.orElse(() => "fallback")
|
|
* )
|
|
*
|
|
* console.log(match("a"))
|
|
* // Output: "ok"
|
|
*
|
|
* console.log(match("b"))
|
|
* // Output: "fallback"
|
|
* ```
|
|
*
|
|
* @category Completion
|
|
* @since 1.0.0
|
|
*/
|
|
export const orElse: <RA, Ret, F extends (_: RA) => Ret>(
|
|
f: F
|
|
) => <I, R, A, Pr>(
|
|
self: Matcher<I, R, RA, A, Pr, Ret>
|
|
) => [Pr] extends [never] ? (input: I) => Unify<ReturnType<F> | A> : Unify<ReturnType<F> | A> = internal.orElse
|
|
|
|
// TODO(4.0): Rename to "orThrow"? Like Either.getOrThrow
|
|
/**
|
|
* Throws an error if no pattern matches.
|
|
*
|
|
* **Details**
|
|
*
|
|
* This function finalizes a matcher by ensuring that if no patterns match, an
|
|
* error is thrown. It is useful when all cases should be covered, and any
|
|
* unexpected input should trigger an error instead of returning a default
|
|
* value.
|
|
*
|
|
* When used, this function removes the need for an explicit fallback case and
|
|
* ensures that an unmatched value is never silently ignored.
|
|
*
|
|
* @category Completion
|
|
* @since 1.0.0
|
|
*/
|
|
export const orElseAbsurd: <I, R, RA, A, Pr, Ret>(
|
|
self: Matcher<I, R, RA, A, Pr, Ret>
|
|
) => [Pr] extends [never] ? (input: I) => Unify<A> : Unify<A> = internal.orElseAbsurd
|
|
|
|
/**
|
|
* Wraps the match result in an `Either`, distinguishing matched and unmatched
|
|
* cases.
|
|
*
|
|
* **Details**
|
|
*
|
|
* This function ensures that the result of a matcher is always wrapped in an
|
|
* `Either`, allowing clear differentiation between successful matches
|
|
* (`Right(value)`) and cases where no pattern matched (`Left(unmatched
|
|
* value)`).
|
|
*
|
|
* This approach is particularly useful when handling optional values or when an
|
|
* unmatched case should be explicitly handled rather than returning a default
|
|
* value or throwing an error.
|
|
*
|
|
* **Example** (Extracting a User Role with `Match.either`)
|
|
*
|
|
* ```ts
|
|
* import { Match } from "effect"
|
|
*
|
|
* type User = { readonly role: "admin" | "editor" | "viewer" }
|
|
*
|
|
* // Create a matcher to extract user roles
|
|
* const getRole = Match.type<User>().pipe(
|
|
* Match.when({ role: "admin" }, () => "Has full access"),
|
|
* Match.when({ role: "editor" }, () => "Can edit content"),
|
|
* Match.either // Wrap the result in an Either
|
|
* )
|
|
*
|
|
* console.log(getRole({ role: "admin" }))
|
|
* // Output: { _id: 'Either', _tag: 'Right', right: 'Has full access' }
|
|
*
|
|
* console.log(getRole({ role: "viewer" }))
|
|
* // Output: { _id: 'Either', _tag: 'Left', left: { role: 'viewer' } }
|
|
* ```
|
|
*
|
|
* @category Completion
|
|
* @since 1.0.0
|
|
*/
|
|
export const either: <I, F, R, A, Pr, Ret>(
|
|
self: Matcher<I, F, R, A, Pr, Ret>
|
|
) => [Pr] extends [never] ? (input: I) => Either.Either<Unify<A>, R> : Either.Either<Unify<A>, R> = internal.either
|
|
|
|
/**
|
|
* Wraps the match result in an `Option`, representing an optional match.
|
|
*
|
|
* **Details**
|
|
*
|
|
* This function ensures that the result of a matcher is wrapped in an `Option`,
|
|
* making it easy to handle cases where no pattern matches. If a match is found,
|
|
* it returns `Some(value)`, otherwise, it returns `None`.
|
|
*
|
|
* This is useful in cases where a missing match is expected and should be
|
|
* handled explicitly rather than throwing an error or returning a default
|
|
* value.
|
|
*
|
|
* **Example** (Extracting a User Role with `Match.option`)
|
|
*
|
|
* ```ts
|
|
* import { Match } from "effect"
|
|
*
|
|
* type User = { readonly role: "admin" | "editor" | "viewer" }
|
|
*
|
|
* // Create a matcher to extract user roles
|
|
* const getRole = Match.type<User>().pipe(
|
|
* Match.when({ role: "admin" }, () => "Has full access"),
|
|
* Match.when({ role: "editor" }, () => "Can edit content"),
|
|
* Match.option // Wrap the result in an Option
|
|
* )
|
|
*
|
|
* console.log(getRole({ role: "admin" }))
|
|
* // Output: { _id: 'Option', _tag: 'Some', value: 'Has full access' }
|
|
*
|
|
* console.log(getRole({ role: "viewer" }))
|
|
* // Output: { _id: 'Option', _tag: 'None' }
|
|
* ```
|
|
*
|
|
* @category Completion
|
|
* @since 1.0.0
|
|
*/
|
|
export const option: <I, F, R, A, Pr, Ret>(
|
|
self: Matcher<I, F, R, A, Pr, Ret>
|
|
) => [Pr] extends [never] ? (input: I) => Option.Option<Unify<A>> : Option.Option<Unify<A>> = internal.option
|
|
|
|
/**
|
|
* The `Match.exhaustive` method finalizes the pattern matching process by
|
|
* ensuring that all possible cases are accounted for. If any case is missing,
|
|
* TypeScript will produce a type error. This is particularly useful when
|
|
* working with unions, as it helps prevent unintended gaps in pattern matching.
|
|
*
|
|
* **Example** (Ensuring All Cases Are Covered)
|
|
*
|
|
* ```ts
|
|
* import { Match } from "effect"
|
|
*
|
|
* // Create a matcher for string or number values
|
|
* const match = Match.type<string | number>().pipe(
|
|
* // Match when the value is a number
|
|
* Match.when(Match.number, (n) => `number: ${n}`),
|
|
* // Mark the match as exhaustive, ensuring all cases are handled
|
|
* // TypeScript will throw an error if any case is missing
|
|
* // @ts-expect-error Type 'string' is not assignable to type 'never'
|
|
* Match.exhaustive
|
|
* )
|
|
* ```
|
|
*
|
|
* @category Completion
|
|
* @since 1.0.0
|
|
*/
|
|
export const exhaustive: <I, F, A, Pr, Ret>(
|
|
self: Matcher<I, F, never, A, Pr, Ret>
|
|
) => [Pr] extends [never] ? (u: I) => Unify<A> : Unify<A> = internal.exhaustive
|
|
|
|
/**
|
|
* @since 1.0.0
|
|
* @category Symbols
|
|
*/
|
|
export const SafeRefinementId = Symbol.for("effect/SafeRefinement")
|
|
|
|
/**
|
|
* @since 1.0.0
|
|
* @category Symbols
|
|
*/
|
|
export type SafeRefinementId = typeof SafeRefinementId
|
|
|
|
/**
|
|
* @category Model
|
|
* @since 1.0.0
|
|
*/
|
|
export interface SafeRefinement<in A, out R = A> {
|
|
readonly [SafeRefinementId]: (a: A) => R
|
|
}
|
|
|
|
const Fail = Symbol.for("effect/Fail")
|
|
type Fail = typeof Fail
|
|
|
|
/**
|
|
* @since 1.0.0
|
|
*/
|
|
export declare namespace Types {
|
|
/**
|
|
* @since 1.0.0
|
|
*/
|
|
export type WhenMatch<R, P> =
|
|
// check for any
|
|
[0] extends [1 & R] ? ResolvePred<P> :
|
|
P extends SafeRefinement<infer SP, never> ? SP
|
|
: P extends Predicate.Refinement<infer _R, infer RP>
|
|
// try to narrow refinement
|
|
? [Extract<R, RP>] extends [infer X] ? [X] extends [never]
|
|
// fallback to original refinement
|
|
? RP
|
|
: X
|
|
: never
|
|
: P extends PredicateA<infer PP> ? PP
|
|
: ExtractMatch<R, P>
|
|
|
|
/**
|
|
* @since 1.0.0
|
|
*/
|
|
export type NotMatch<R, P> = Exclude<R, ExtractMatch<R, PForNotMatch<P>>>
|
|
|
|
type PForNotMatch<P> = [ToInvertedRefinement<P>] extends [infer X] ? X
|
|
: never
|
|
|
|
/**
|
|
* @since 1.0.0
|
|
*/
|
|
export type PForMatch<P> = [ResolvePred<P>] extends [infer X] ? X
|
|
: never
|
|
|
|
/**
|
|
* @since 1.0.0
|
|
*/
|
|
export type PForExclude<P> = [SafeRefinementR<ToSafeRefinement<P>>] extends [infer X] ? X
|
|
: never
|
|
|
|
// utilities
|
|
type PredicateA<A> = Predicate.Predicate<A> | Predicate.Refinement<A, A>
|
|
|
|
type SafeRefinementR<A> = A extends never ? never
|
|
: A extends SafeRefinement<infer _, infer R> ? R
|
|
: A extends Function ? A
|
|
: A extends Record<string, any> ? { [K in keyof A]: SafeRefinementR<A[K]> }
|
|
: A
|
|
|
|
type ResolvePred<A, Input = any> = A extends never ? never
|
|
: A extends SafeRefinement<infer _A, infer _R> ? _A
|
|
: A extends Predicate.Refinement<Input, infer P> ? P
|
|
: A extends Predicate.Predicate<infer P> ? P
|
|
: A extends Record<string, any> ? { [K in keyof A]: ResolvePred<A[K]> }
|
|
: A
|
|
|
|
type ToSafeRefinement<A> = A extends never ? never
|
|
: A extends Predicate.Refinement<any, infer P> ? SafeRefinement<P, P>
|
|
: A extends Predicate.Predicate<infer P> ? SafeRefinement<P, never>
|
|
: A extends SafeRefinement<any> ? A
|
|
: A extends Record<string, any> ? { [K in keyof A]: ToSafeRefinement<A[K]> }
|
|
: NonLiteralsTo<A, never>
|
|
|
|
type ToInvertedRefinement<A> = A extends never ? never
|
|
: A extends Predicate.Refinement<any, infer P> ? SafeRefinement<P>
|
|
: A extends Predicate.Predicate<infer _P> ? SafeRefinement<never>
|
|
: A extends SafeRefinement<infer _A, infer _R> ? SafeRefinement<_R>
|
|
: A extends Record<string, any> ? { [K in keyof A]: ToInvertedRefinement<A[K]> }
|
|
: NonLiteralsTo<A, never>
|
|
|
|
type NonLiteralsTo<A, T> = [A] extends [string | number | boolean | bigint] ? [string] extends [A] ? T
|
|
: [number] extends [A] ? T
|
|
: [boolean] extends [A] ? T
|
|
: [bigint] extends [A] ? T
|
|
: A
|
|
: A
|
|
|
|
/**
|
|
* @since 1.0.0
|
|
*/
|
|
export type PatternBase<A> = A extends ReadonlyArray<infer _T> ? ReadonlyArray<any> | PatternPrimitive<A>
|
|
: A extends Record<string, any> ? Partial<
|
|
{ [K in keyof A]: PatternPrimitive<A[K] & {}> | PatternBase<A[K] & {}> }
|
|
>
|
|
: never
|
|
|
|
/**
|
|
* @since 1.0.0
|
|
*/
|
|
export type PatternPrimitive<A> = PredicateA<A> | A | SafeRefinement<any>
|
|
|
|
/**
|
|
* @since 1.0.0
|
|
*/
|
|
export interface Without<out X> {
|
|
readonly _tag: "Without"
|
|
readonly _X: X
|
|
}
|
|
|
|
/**
|
|
* @since 1.0.0
|
|
*/
|
|
export interface Only<out X> {
|
|
readonly _tag: "Only"
|
|
readonly _X: X
|
|
}
|
|
|
|
/**
|
|
* @since 1.0.0
|
|
*/
|
|
export type AddWithout<A, X> = [A] extends [Without<infer WX>] ? Without<X | WX>
|
|
: [A] extends [Only<infer OX>] ? Only<Exclude<OX, X>>
|
|
: never
|
|
|
|
/**
|
|
* @since 1.0.0
|
|
*/
|
|
export type AddOnly<A, X> = [A] extends [Without<infer WX>] ? [X] extends [WX] ? never
|
|
: Only<X>
|
|
: [A] extends [Only<infer OX>] ? [X] extends [OX] ? Only<X>
|
|
: never
|
|
: never
|
|
|
|
/**
|
|
* @since 1.0.0
|
|
*/
|
|
export type ApplyFilters<I, A> = A extends Only<infer X> ? X
|
|
: A extends Without<infer X> ? Exclude<I, X>
|
|
: never
|
|
|
|
/**
|
|
* @since 1.0.0
|
|
*/
|
|
export type Tags<D extends string, P> = P extends Record<D, infer X> ? X : never
|
|
|
|
/**
|
|
* @since 1.0.0
|
|
*/
|
|
export type ArrayToIntersection<A extends ReadonlyArray<any>> = T.UnionToIntersection<
|
|
A[number]
|
|
>
|
|
|
|
/**
|
|
* @since 1.0.0
|
|
*/
|
|
export type ExtractMatch<I, P> = [ExtractAndNarrow<I, P>] extends [infer EI] ? EI
|
|
: never
|
|
|
|
type Replace<A, B> = A extends Function ? A
|
|
: A extends Record<string | number, any> ? { [K in keyof A]: K extends keyof B ? Replace<A[K], B[K]> : A[K] }
|
|
: [B] extends [A] ? B
|
|
: A
|
|
|
|
type MaybeReplace<I, P> = [P] extends [I] ? P
|
|
: [I] extends [P] ? Replace<I, P>
|
|
: Fail
|
|
|
|
type BuiltInObjects =
|
|
| Function
|
|
| Date
|
|
| RegExp
|
|
| Generator
|
|
| { readonly [Symbol.toStringTag]: string }
|
|
|
|
type IsPlainObject<T> = T extends BuiltInObjects ? false
|
|
: T extends Record<string, any> ? true
|
|
: false
|
|
|
|
type Simplify<A> = { [K in keyof A]: A[K] } & {}
|
|
|
|
type ExtractAndNarrow<Input, P> = P extends Predicate.Refinement<infer _In, infer _Out> ?
|
|
_Out extends Input ? Extract<_Out, Input>
|
|
: Extract<Input, _Out> :
|
|
P extends SafeRefinement<infer _In, infer _R> ? [0] extends [1 & _R] ? Input
|
|
: _In extends Input ? Extract<_In, Input>
|
|
: Extract<Input, _In>
|
|
: P extends Predicate.Predicate<infer _In> ? Extract<Input, _In>
|
|
: Input extends infer I ? Exclude<
|
|
I extends ReadonlyArray<any> ? P extends ReadonlyArray<any> ? {
|
|
readonly [K in keyof I]: K extends keyof P ? ExtractAndNarrow<I[K], P[K]>
|
|
: I[K]
|
|
} extends infer R ? Fail extends R[keyof R] ? never
|
|
: R
|
|
: never
|
|
: never
|
|
: IsPlainObject<I> extends true ? string extends keyof I ? I extends P ? I
|
|
: never
|
|
: symbol extends keyof I ? I extends P ? I
|
|
: never
|
|
: Simplify<
|
|
& { [RK in Extract<keyof I, keyof P>]-?: ExtractAndNarrow<I[RK], P[RK]> }
|
|
& Omit<I, keyof P>
|
|
> extends infer R ? keyof P extends NonFailKeys<R> ? R
|
|
: never
|
|
: never
|
|
: MaybeReplace<I, P> extends infer R ? [I] extends [R] ? I
|
|
: R
|
|
: never,
|
|
Fail
|
|
> :
|
|
never
|
|
|
|
type NonFailKeys<A> = keyof A & {} extends infer K ? K extends keyof A ? A[K] extends Fail ? never : K
|
|
: never :
|
|
never
|
|
}
|