<A extends Request.Any>(
f: (entry: Request.Entry<A>) => Request.Success<A>
): RequestResolver<A>Constructs a request resolver from a pure function.
Example (Creating a resolver from a pure function)
import { Effect, Request, RequestResolver } from "effect"
interface GetSquareRequest extends Request.Request<number> {
readonly _tag: "GetSquareRequest"
readonly value: number
}
const GetSquareRequest = Request.tagged<GetSquareRequest>("GetSquareRequest")
// Create a resolver from a pure function
const SquareResolver = RequestResolver.fromFunction<GetSquareRequest>(
(entry) => entry.request.value * entry.request.value
)
// Usage
const getSquareEffect = Effect.request(
GetSquareRequest({ value: 5 }),
SquareResolver
)
// Will resolve to 25constructors
Source effect/RequestResolver.ts:33312 lines
export const const fromFunction: <
A extends Request.Any
>(
f: (
entry: Request.Entry<A>
) => Request.Success<A>
) => RequestResolver<A>
Constructs a request resolver from a pure function.
Example (Creating a resolver from a pure function)
import { Effect, Request, RequestResolver } from "effect"
interface GetSquareRequest extends Request.Request<number> {
readonly _tag: "GetSquareRequest"
readonly value: number
}
const GetSquareRequest = Request.tagged<GetSquareRequest>("GetSquareRequest")
// Create a resolver from a pure function
const SquareResolver = RequestResolver.fromFunction<GetSquareRequest>(
(entry) => entry.request.value * entry.request.value
)
// Usage
const getSquareEffect = Effect.request(
GetSquareRequest({ value: 5 }),
SquareResolver
)
// Will resolve to 25
fromFunction = <function (type parameter) A in <A extends Request.Any>(f: (entry: Request.Entry<A>) => Request.Success<A>): RequestResolver<A>A extends import RequestRequest.type Any = Request.Request<any, any, any>Alias for any Request, regardless of its success, error, or service
requirements.
When to use
Use as a generic constraint for APIs that accept any request while preserving
each concrete request's success, error, and service types.
Any>(
f: (
entry: Request.Entry<A>
) => Request.Success<A>
entry: Request.Entry<A>(parameter) entry: {
request: R;
context: Context.Context<[R] extends [Request<infer _A, infer _E, infer _R>] ? _R : never>;
uninterruptible: boolean;
completeUnsafe: (exit: Exit.Exit<[A] extends [Request.Request<infer _A, infer _E, infer _R>] ? _A : never, [A] extends [Request.Request<infer _A, infer _E, infer _R>] ? _E : never>) => void;
}
import RequestRequest.interface Entry<out R>A pending request handed to a RequestResolver.
Details
An entry contains the original request, the fiber context needed to run it,
an uninterruptible flag used by batching and caching internals, and the
completeUnsafe callback used by resolvers to supply the final Exit.
Entry<function (type parameter) A in <A extends Request.Any>(f: (entry: Request.Entry<A>) => Request.Success<A>): RequestResolver<A>A>) => import RequestRequest.type Success<
T extends Request.Request<any, any, any>
> = [T] extends [
Request.Request<infer _A, infer _E, infer _R>
]
? _A
: never
A utility type to extract the value type from a Request.
Example (Extracting a request success type)
import type { Request } from "effect"
interface GetUser extends Request.Request<string, Error> {
readonly _tag: "GetUser"
readonly id: number
}
// Extract the success type from a Request using the utility
type UserSuccess = Request.Success<GetUser> // string
Success<function (type parameter) A in <A extends Request.Any>(f: (entry: Request.Entry<A>) => Request.Success<A>): RequestResolver<A>A>
): interface RequestResolver<in A extends Request.Any>A resolver that executes and completes batched Request entries.
Details
A resolver controls how requests are grouped, delayed, optionally
pre-checked, and finally run. Its runAll method receives a non-empty batch
of Request.Entry values for a single batch key and must complete every
received entry, usually by calling completeUnsafe or one of the Request
completion helpers.
Gotchas
If a resolver finishes without completing an entry, the waiting request fails
because the resolver did not supply a result.
Example (Defining a request resolver)
import { Effect, Exit, RequestResolver } from "effect"
import type { Request } from "effect"
interface GetUserRequest extends Request.Request<string, Error> {
readonly _tag: "GetUserRequest"
readonly id: number
}
// In practice, you would typically use RequestResolver.make() instead
const resolver = RequestResolver.make<GetUserRequest>((entries) =>
Effect.sync(() => {
for (const entry of entries) {
entry.completeUnsafe(Exit.succeed(`User ${entry.request.id}`))
}
})
)
Namespace containing type-level helpers associated with RequestResolver.
RequestResolver<function (type parameter) A in <A extends Request.Any>(f: (entry: Request.Entry<A>) => Request.Success<A>): RequestResolver<A>A> =>
const make: <A extends Request.Any>(
runAll: (
entries: NonEmptyArray<Request.Entry<A>>,
key: unknown
) => Effect.Effect<void, Request.Error<A>>
) => RequestResolver<A>
Constructs a request resolver with the specified method to run requests.
Example (Creating a request resolver)
import { Effect, Exit, Request, RequestResolver } from "effect"
// Define a request type
interface GetUserRequest extends Request.Request<string, Error> {
readonly _tag: "GetUserRequest"
readonly id: number
}
const GetUserRequest = Request.tagged<GetUserRequest>("GetUserRequest")
// Create a resolver that handles the requests
const UserResolver = RequestResolver.make<GetUserRequest>((entries) =>
Effect.sync(() => {
for (const entry of entries) {
// Complete each request with a result
entry.completeUnsafe(Exit.succeed(`User ${entry.request.id}`))
}
})
)
// Use the resolver to handle requests
const getUserEffect = Effect.request(GetUserRequest({ id: 123 }), UserResolver)
make(
(entries: [
Request.Entry<A>,
...Request.Entry<A>[]
]
(parameter) entries: {
0: Request.Entry<A>;
length: number;
toString: () => string;
toLocaleString: { (): string; (locales: string | string[], options?: Intl.NumberFormatOptions & Intl.DateTimeFormatOptions): string };
pop: () => Request.Entry<A> | undefined;
push: (...items: Array<Request.Entry<A>>) => number;
concat: { (...items: Array<ConcatArray<Request.Entry<A>>>): Array<Request.Entry<A>>; (...items: Array<Request.Entry<A> | ConcatArray<Request.Entry<A>>>): Array<Request.Entry<A>> };
join: (separator?: string) => string;
reverse: () => Array<Request.Entry<A>>;
shift: () => Request.Entry<A> | undefined;
slice: (start?: number, end?: number) => Array<Request.Entry<A>>;
sort: (compareFn?: ((a: Request.Entry<A>, b: Request.Entry<A>) => number) | undefined) => [Request.Entry<A>, ...Request.Entry<A>[]];
splice: { (start: number, deleteCount?: number): Array<Request.Entry<A>>; (start: number, deleteCount: number, ...items: Array<Request.Entry<A>>): Array<Request.Entry<A>> };
unshift: (...items: Array<Request.Entry<A>>) => number;
indexOf: (searchElement: Request.Entry<A>, fromIndex?: number) => number;
lastIndexOf: (searchElement: Request.Entry<A>, fromIndex?: number) => number;
every: { (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => value is S, thisArg?: any): this is S[]; (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => unknown, thisArg?: a…;
some: (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => unknown, thisArg?: any) => boolean;
forEach: (callbackfn: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => void, thisArg?: any) => void;
map: (callbackfn: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => U, thisArg?: any) => Array<U>;
filter: { (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => value is S, thisArg?: any): Array<S>; (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => unknown, thisArg?: any)…;
reduce: { (callbackfn: (previousValue: Request.Entry<A>, currentValue: Request.Entry<A>, currentIndex: number, array: Array<Request.Entry<A>>) => Request.Entry<A>): Request.Entry<A>; (callbackfn: (previousValue: Request.Entry<A>, currentValue: Req…;
reduceRight: { (callbackfn: (previousValue: Request.Entry<A>, currentValue: Request.Entry<A>, currentIndex: number, array: Array<Request.Entry<A>>) => Request.Entry<A>): Request.Entry<A>; (callbackfn: (previousValue: Request.Entry<A>, currentValue: Req…;
find: { (predicate: (value: Request.Entry<A>, index: number, obj: Array<Request.Entry<A>>) => value is S, thisArg?: any): S | undefined; (predicate: (value: Request.Entry<A>, index: number, obj: Array<Request.Entry<A>>) => unknown, thisArg?: any…;
findIndex: (predicate: (value: Request.Entry<A>, index: number, obj: Array<Request.Entry<A>>) => unknown, thisArg?: any) => number;
fill: (value: Request.Entry<A>, start?: number, end?: number) => [Request.Entry<A>, ...Request.Entry<A>[]];
copyWithin: (target: number, start: number, end?: number) => [Request.Entry<A>, ...Request.Entry<A>[]];
entries: () => ArrayIterator<[number, Request.Entry<A>]>;
keys: () => ArrayIterator<number>;
values: () => ArrayIterator<Request.Entry<A>>;
includes: (searchElement: Request.Entry<A>, fromIndex?: number) => boolean;
flatMap: (callback: (this: This, value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => U | ReadonlyArray<U>, thisArg?: This | undefined) => Array<U>;
flat: (this: A, depth?: D | undefined) => Array<FlatArray<A, D>>;
at: (index: number) => Request.Entry<A> | undefined;
findLast: { (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => value is S, thisArg?: any): S | undefined; (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => unknown, thisArg?:…;
findLastIndex: (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => unknown, thisArg?: any) => number;
toReversed: () => Array<Request.Entry<A>>;
toSorted: (compareFn?: ((a: Request.Entry<A>, b: Request.Entry<A>) => number) | undefined) => Array<Request.Entry<A>>;
toSpliced: { (start: number, deleteCount: number, ...items: Array<Request.Entry<A>>): Array<Request.Entry<A>>; (start: number, deleteCount?: number): Array<Request.Entry<A>> };
with: (index: number, value: Request.Entry<A>) => Array<Request.Entry<A>>;
}
import EffectEffect.const sync: <A>(
thunk: LazyArg<A>
) => Effect<A>
Creates an Effect that represents a synchronous side-effectful computation.
When to use
Use when you need to wrap a synchronous side-effectful operation that is not
expected to throw.
Details
The provided function is evaluated lazily when the effect runs.
Gotchas
The function must not throw. If it throws, the thrown value is treated as a
defect, not as a typed failure. Use try when throwing is expected.
Example (Capturing synchronous logging in an Effect)
import { Effect } from "effect"
const log = (message: string) =>
Effect.sync(() => {
console.log(message) // side effect
})
// ┌─── Effect<void, never, never>
// ▼
const program = log("Hello, World!")
sync(() => {
for (let let i: numberi = 0; let i: numberi < entries: [
Request.Entry<A>,
...Request.Entry<A>[]
]
(parameter) entries: {
0: Request.Entry<A>;
length: number;
toString: () => string;
toLocaleString: { (): string; (locales: string | string[], options?: Intl.NumberFormatOptions & Intl.DateTimeFormatOptions): string };
pop: () => Request.Entry<A> | undefined;
push: (...items: Array<Request.Entry<A>>) => number;
concat: { (...items: Array<ConcatArray<Request.Entry<A>>>): Array<Request.Entry<A>>; (...items: Array<Request.Entry<A> | ConcatArray<Request.Entry<A>>>): Array<Request.Entry<A>> };
join: (separator?: string) => string;
reverse: () => Array<Request.Entry<A>>;
shift: () => Request.Entry<A> | undefined;
slice: (start?: number, end?: number) => Array<Request.Entry<A>>;
sort: (compareFn?: ((a: Request.Entry<A>, b: Request.Entry<A>) => number) | undefined) => [Request.Entry<A>, ...Request.Entry<A>[]];
splice: { (start: number, deleteCount?: number): Array<Request.Entry<A>>; (start: number, deleteCount: number, ...items: Array<Request.Entry<A>>): Array<Request.Entry<A>> };
unshift: (...items: Array<Request.Entry<A>>) => number;
indexOf: (searchElement: Request.Entry<A>, fromIndex?: number) => number;
lastIndexOf: (searchElement: Request.Entry<A>, fromIndex?: number) => number;
every: { (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => value is S, thisArg?: any): this is S[]; (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => unknown, thisArg?: a…;
some: (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => unknown, thisArg?: any) => boolean;
forEach: (callbackfn: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => void, thisArg?: any) => void;
map: (callbackfn: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => U, thisArg?: any) => Array<U>;
filter: { (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => value is S, thisArg?: any): Array<S>; (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => unknown, thisArg?: any)…;
reduce: { (callbackfn: (previousValue: Request.Entry<A>, currentValue: Request.Entry<A>, currentIndex: number, array: Array<Request.Entry<A>>) => Request.Entry<A>): Request.Entry<A>; (callbackfn: (previousValue: Request.Entry<A>, currentValue: Req…;
reduceRight: { (callbackfn: (previousValue: Request.Entry<A>, currentValue: Request.Entry<A>, currentIndex: number, array: Array<Request.Entry<A>>) => Request.Entry<A>): Request.Entry<A>; (callbackfn: (previousValue: Request.Entry<A>, currentValue: Req…;
find: { (predicate: (value: Request.Entry<A>, index: number, obj: Array<Request.Entry<A>>) => value is S, thisArg?: any): S | undefined; (predicate: (value: Request.Entry<A>, index: number, obj: Array<Request.Entry<A>>) => unknown, thisArg?: any…;
findIndex: (predicate: (value: Request.Entry<A>, index: number, obj: Array<Request.Entry<A>>) => unknown, thisArg?: any) => number;
fill: (value: Request.Entry<A>, start?: number, end?: number) => [Request.Entry<A>, ...Request.Entry<A>[]];
copyWithin: (target: number, start: number, end?: number) => [Request.Entry<A>, ...Request.Entry<A>[]];
entries: () => ArrayIterator<[number, Request.Entry<A>]>;
keys: () => ArrayIterator<number>;
values: () => ArrayIterator<Request.Entry<A>>;
includes: (searchElement: Request.Entry<A>, fromIndex?: number) => boolean;
flatMap: (callback: (this: This, value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => U | ReadonlyArray<U>, thisArg?: This | undefined) => Array<U>;
flat: (this: A, depth?: D | undefined) => Array<FlatArray<A, D>>;
at: (index: number) => Request.Entry<A> | undefined;
findLast: { (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => value is S, thisArg?: any): S | undefined; (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => unknown, thisArg?:…;
findLastIndex: (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => unknown, thisArg?: any) => number;
toReversed: () => Array<Request.Entry<A>>;
toSorted: (compareFn?: ((a: Request.Entry<A>, b: Request.Entry<A>) => number) | undefined) => Array<Request.Entry<A>>;
toSpliced: { (start: number, deleteCount: number, ...items: Array<Request.Entry<A>>): Array<Request.Entry<A>>; (start: number, deleteCount?: number): Array<Request.Entry<A>> };
with: (index: number, value: Request.Entry<A>) => Array<Request.Entry<A>>;
}
length: numberlength; let i: numberi++) {
const const entry: Request.Entry<A>const entry: {
request: R;
context: Context.Context<[R] extends [Request<infer _A, infer _E, infer _R>] ? _R : never>;
uninterruptible: boolean;
completeUnsafe: (exit: Exit.Exit<[A] extends [Request.Request<infer _A, infer _E, infer _R>] ? _A : never, [A] extends [Request.Request<infer _A, infer _E, infer _R>] ? _E : never>) => void;
}
entries: [
Request.Entry<A>,
...Request.Entry<A>[]
]
(parameter) entries: {
0: Request.Entry<A>;
length: number;
toString: () => string;
toLocaleString: { (): string; (locales: string | string[], options?: Intl.NumberFormatOptions & Intl.DateTimeFormatOptions): string };
pop: () => Request.Entry<A> | undefined;
push: (...items: Array<Request.Entry<A>>) => number;
concat: { (...items: Array<ConcatArray<Request.Entry<A>>>): Array<Request.Entry<A>>; (...items: Array<Request.Entry<A> | ConcatArray<Request.Entry<A>>>): Array<Request.Entry<A>> };
join: (separator?: string) => string;
reverse: () => Array<Request.Entry<A>>;
shift: () => Request.Entry<A> | undefined;
slice: (start?: number, end?: number) => Array<Request.Entry<A>>;
sort: (compareFn?: ((a: Request.Entry<A>, b: Request.Entry<A>) => number) | undefined) => [Request.Entry<A>, ...Request.Entry<A>[]];
splice: { (start: number, deleteCount?: number): Array<Request.Entry<A>>; (start: number, deleteCount: number, ...items: Array<Request.Entry<A>>): Array<Request.Entry<A>> };
unshift: (...items: Array<Request.Entry<A>>) => number;
indexOf: (searchElement: Request.Entry<A>, fromIndex?: number) => number;
lastIndexOf: (searchElement: Request.Entry<A>, fromIndex?: number) => number;
every: { (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => value is S, thisArg?: any): this is S[]; (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => unknown, thisArg?: a…;
some: (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => unknown, thisArg?: any) => boolean;
forEach: (callbackfn: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => void, thisArg?: any) => void;
map: (callbackfn: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => U, thisArg?: any) => Array<U>;
filter: { (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => value is S, thisArg?: any): Array<S>; (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => unknown, thisArg?: any)…;
reduce: { (callbackfn: (previousValue: Request.Entry<A>, currentValue: Request.Entry<A>, currentIndex: number, array: Array<Request.Entry<A>>) => Request.Entry<A>): Request.Entry<A>; (callbackfn: (previousValue: Request.Entry<A>, currentValue: Req…;
reduceRight: { (callbackfn: (previousValue: Request.Entry<A>, currentValue: Request.Entry<A>, currentIndex: number, array: Array<Request.Entry<A>>) => Request.Entry<A>): Request.Entry<A>; (callbackfn: (previousValue: Request.Entry<A>, currentValue: Req…;
find: { (predicate: (value: Request.Entry<A>, index: number, obj: Array<Request.Entry<A>>) => value is S, thisArg?: any): S | undefined; (predicate: (value: Request.Entry<A>, index: number, obj: Array<Request.Entry<A>>) => unknown, thisArg?: any…;
findIndex: (predicate: (value: Request.Entry<A>, index: number, obj: Array<Request.Entry<A>>) => unknown, thisArg?: any) => number;
fill: (value: Request.Entry<A>, start?: number, end?: number) => [Request.Entry<A>, ...Request.Entry<A>[]];
copyWithin: (target: number, start: number, end?: number) => [Request.Entry<A>, ...Request.Entry<A>[]];
entries: () => ArrayIterator<[number, Request.Entry<A>]>;
keys: () => ArrayIterator<number>;
values: () => ArrayIterator<Request.Entry<A>>;
includes: (searchElement: Request.Entry<A>, fromIndex?: number) => boolean;
flatMap: (callback: (this: This, value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => U | ReadonlyArray<U>, thisArg?: This | undefined) => Array<U>;
flat: (this: A, depth?: D | undefined) => Array<FlatArray<A, D>>;
at: (index: number) => Request.Entry<A> | undefined;
findLast: { (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => value is S, thisArg?: any): S | undefined; (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => unknown, thisArg?:…;
findLastIndex: (predicate: (value: Request.Entry<A>, index: number, array: Array<Request.Entry<A>>) => unknown, thisArg?: any) => number;
toReversed: () => Array<Request.Entry<A>>;
toSorted: (compareFn?: ((a: Request.Entry<A>, b: Request.Entry<A>) => number) | undefined) => Array<Request.Entry<A>>;
toSpliced: { (start: number, deleteCount: number, ...items: Array<Request.Entry<A>>): Array<Request.Entry<A>>; (start: number, deleteCount?: number): Array<Request.Entry<A>> };
with: (index: number, value: Request.Entry<A>) => Array<Request.Entry<A>>;
}
let i: numberi]
const entry: Request.Entry<A>const entry: {
request: R;
context: Context.Context<[R] extends [Request<infer _A, infer _E, infer _R>] ? _R : never>;
uninterruptible: boolean;
completeUnsafe: (exit: Exit.Exit<[A] extends [Request.Request<infer _A, infer _E, infer _R>] ? _A : never, [A] extends [Request.Request<infer _A, infer _E, infer _R>] ? _E : never>) => void;
}
Entry<A>.completeUnsafe(exit: Exit.Exit<[A] extends [Request.Request<infer _A, infer _E, infer _R>] ? _A : never, [A] extends [Request.Request<infer _A, infer _E, infer _R>] ? _E : never>): voidcompleteUnsafe(exitSucceed<A>(a: A): Exit.Exit<A>exitSucceed(f: (
entry: Request.Entry<A>
) => Request.Success<A>
const entry: Request.Entry<A>const entry: {
request: R;
context: Context.Context<[R] extends [Request<infer _A, infer _E, infer _R>] ? _R : never>;
uninterruptible: boolean;
completeUnsafe: (exit: Exit.Exit<[A] extends [Request.Request<infer _A, infer _E, infer _R>] ? _A : never, [A] extends [Request.Request<infer _A, infer _E, infer _R>] ? _E : never>) => void;
}