effect-io-ai

Package: effect
Module: Data

Data.TaggedEnum.WithGenerics

Defines a tagged enum shape that accepts generic type parameters.

When to use

Use when variant payloads need to be parameterized, such as Result<E, A>.

Details

Extend this interface and set taggedEnum to your union type, using this["A"], this["B"], etc. as placeholders for the generics. The Count parameter declares how many generics are used (up to 4).

Example (Defining a generic tagged enum)

import { Data } from "effect"

type MyResult<E, A> = Data.TaggedEnum<{
  Failure: { readonly error: E }
  Success: { readonly value: A }
}>

interface MyResultDef extends Data.TaggedEnum.WithGenerics<2> {
  readonly taggedEnum: MyResult<this["A"], this["B"]>
}

const { Failure, Success } = Data.taggedEnum<MyResultDef>()

const ok = Success({ value: 42 })
// ok: { readonly _tag: "Success"; readonly value: number }

See

• Kind — apply concrete types to a WithGenerics definition
• taggedEnum — constructors and matchers

Signature

export interface WithGenerics<Count extends number> {
    readonly taggedEnum: { readonly _tag: string }
    readonly numberOfGenerics: Count

    readonly A: unknown
    readonly B: unknown
    readonly C: unknown
    readonly D: unknown
  }

Source

Since v2.0.0