<Tag extends string>(tag: Tag): new <A extends Record<string, any> = {}>(
args: Types.VoidIfEmpty<{
readonly [P in keyof A as P extends "_tag" ? never : P]: A[P]
}>
) => Cause.YieldableError & { readonly _tag: Tag } & Readonly<A>Creates a tagged error class with a _tag discriminator.
When to use
Use when you need domain errors with discriminated-union handling.
Details
Like Error, but instances also carry a readonly _tag property,
enabling Effect.catchTag and Effect.catchTags for tag-based recovery.
The _tag is excluded from the constructor argument. Yielding an instance
inside Effect.gen fails the effect with this error.
Example (Recovering by tag)
import { Data, Effect } from "effect"
class NotFound extends Data.TaggedError("NotFound")<{
readonly resource: string
}> {}
class Forbidden extends Data.TaggedError("Forbidden")<{
readonly reason: string
}> {}
const program = Effect.gen(function*() {
return yield* new NotFound({ resource: "/users/42" })
})
const recovered = program.pipe(
Effect.catchTag("NotFound", (e) =>
Effect.succeed(`missing: ${e.resource}`))
)Source effect/Data.ts:7705 lines
export const const TaggedError: <Tag extends string>(
tag: Tag
) => new <A extends Record<string, any> = {}>(
args: Types.VoidIfEmpty<{
readonly [P in keyof A as P extends "_tag"
? never
: P]: A[P]
}>
) => Cause.YieldableError & {
readonly _tag: Tag
} & Readonly<A>
Creates a tagged error class with a _tag discriminator.
When to use
Use when you need domain errors with discriminated-union handling.
Details
Like
Error
, but instances also carry a readonly _tag property,
enabling Effect.catchTag and Effect.catchTags for tag-based recovery.
The _tag is excluded from the constructor argument. Yielding an instance
inside Effect.gen fails the effect with this error.
Example (Recovering by tag)
import { Data, Effect } from "effect"
class NotFound extends Data.TaggedError("NotFound")<{
readonly resource: string
}> {}
class Forbidden extends Data.TaggedError("Forbidden")<{
readonly reason: string
}> {}
const program = Effect.gen(function*() {
return yield* new NotFound({ resource: "/users/42" })
})
const recovered = program.pipe(
Effect.catchTag("NotFound", (e) =>
Effect.succeed(`missing: ${e.resource}`))
)
TaggedError: <function (type parameter) Tag in <Tag extends string>(tag: Tag): new <A extends Record<string, any> = {}>(args: Types.VoidIfEmpty<{ readonly [P in keyof A as P extends "_tag" ? never : P]: A[P]; }>) => Cause.YieldableError & {
readonly _tag: Tag;
} & Readonly<A>
tag: Tag extends stringtag: function (type parameter) Tag in <Tag extends string>(tag: Tag): new <A extends Record<string, any> = {}>(args: Types.VoidIfEmpty<{ readonly [P in keyof A as P extends "_tag" ? never : P]: A[P]; }>) => Cause.YieldableError & {
readonly _tag: Tag;
} & Readonly<A>
function (type parameter) A in <A extends Record<string, any> = {}>(args: Types.VoidIfEmpty<{ readonly [P in keyof A as P extends "_tag" ? never : P]: A[P]; }>): Cause.YieldableError & {
readonly _tag: Tag;
} & Readonly<A>
type Record<K extends keyof any, T> = {
[P in K]: T
}
Construct a type with a set of properties K of type T
Record<string, any> = {}>(
args: Types.VoidIfEmpty<{
readonly [P in keyof A as P extends "_tag"
? never
: P]: A[P]
}>
import TypesTypes.type VoidIfEmpty<S> =
keyof S extends never ? void : S
Conditional type that returns void if S is an empty object type,
otherwise returns S.
When to use
Use to erase an empty object type from an API result or parameter position.
VoidIfEmpty<{ readonly [function (type parameter) PP in keyof function (type parameter) A in <A extends Record<string, any> = {}>(args: Types.VoidIfEmpty<{ readonly [P in keyof A as P extends "_tag" ? never : P]: A[P]; }>): Cause.YieldableError & {
readonly _tag: Tag;
} & Readonly<A>
function (type parameter) PP extends "_tag" ? never : function (type parameter) PP]: function (type parameter) A in <A extends Record<string, any> = {}>(args: Types.VoidIfEmpty<{ readonly [P in keyof A as P extends "_tag" ? never : P]: A[P]; }>): Cause.YieldableError & {
readonly _tag: Tag;
} & Readonly<A>
function (type parameter) PP] }>
) => import CauseCause.type Cause.YieldableError = /*unresolved*/ anyYieldableError & { readonly _tag: Tag extends string_tag: function (type parameter) Tag in <Tag extends string>(tag: Tag): new <A extends Record<string, any> = {}>(args: Types.VoidIfEmpty<{ readonly [P in keyof A as P extends "_tag" ? never : P]: A[P]; }>) => Cause.YieldableError & {
readonly _tag: Tag;
} & Readonly<A>
type Readonly<T> = {
readonly [P in keyof T]: T[P]
}
Make all properties in T readonly
Readonly<function (type parameter) A in <A extends Record<string, any> = {}>(args: Types.VoidIfEmpty<{ readonly [P in keyof A as P extends "_tag" ? never : P]: A[P]; }>): Cause.YieldableError & {
readonly _tag: Tag;
} & Readonly<A>
import corecore.const TaggedError: <Tag extends string>(
tag: Tag
) => new <A extends Record<string, any> = {}>(
args: Types.VoidIfEmpty<{
readonly [P in keyof A as P extends "_tag"
? never
: P]: A[P]
}>
) => Cause.YieldableError & {
readonly _tag: Tag
} & Readonly<A>
Referenced by 46 symbols
ConfigProvider.SourceErrorCron.CronParseErrorEncoding.EncodingErrorGraph.GraphErrorPlatformError.BadArgumentPlatformError.PlatformErrorSchema.SchemaErrorSchemaError.SchemaErrorDurableQueueStore.DurableQueueError (hyperlink-ts)DynamicConfig.ConfigKeyNotSwappable (hyperlink-ts)Hyperlink.DuplicateGroupId (hyperlink-ts)Hyperlink.DuplicateHyperlinkKey (hyperlink-ts)Hyperlink.DuplicateInstance (hyperlink-ts)Hyperlink.EffectFnMissingPayload (hyperlink-ts)Hyperlink.IdentityMultiNode (hyperlink-ts)Hyperlink.IdentitySelfRequired (hyperlink-ts)Hyperlink.InstanceRoutingError (hyperlink-ts)Hyperlink.LocalOnlyMethod (hyperlink-ts)Hyperlink.LookupClientError (hyperlink-ts)Hyperlink.MissingClientProtocol (hyperlink-ts)Hyperlink.MissingContractMethod (hyperlink-ts)Hyperlink.ProtocolMismatch (hyperlink-ts)Lookup.LookupUnaddressed (hyperlink-ts)Node.AddressLessClaimLost (hyperlink-ts)Node.ClientsNodeMismatch (hyperlink-ts)Node.ContractMismatch (hyperlink-ts)Node.HttpListenRequiresHttp (hyperlink-ts)Node.InvalidHttpTarget (hyperlink-ts)Node.ListenTagNodeRequired (hyperlink-ts)Node.ListenUseProtocol (hyperlink-ts)Node.MalformedNode (hyperlink-ts)Node.NPipeListenRequiresIpc (hyperlink-ts)Node.NPipeRequiresWindows (hyperlink-ts)Node.NodeUnreachable (hyperlink-ts)Node.ProtocolKindMismatch (hyperlink-ts)Node.ProtocolUnanswered (hyperlink-ts)Node.ServiceNotReady (hyperlink-ts)Node.ServiceNotServed (hyperlink-ts)Node.UnaddressedNode (hyperlink-ts)Node.UnixListenRequiresIpc (hyperlink-ts)+6 more