effect-io-ai

Package: effect
Module: Effect

Effect.validateFirst

This function is similar to validateAll but with a key difference: it returns the first successful result or all errors if none of the operations succeed.

Details

This function processes a collection of elements and applies an effectful operation to each. Unlike validateAll, which accumulates both successes and failures, Effect.validateFirst stops and returns the first success it encounters. If no success occurs, it returns all accumulated errors. This can be useful when you are interested in the first successful result and want to avoid processing further once a valid result is found.

Example

import { Effect, Console } from "effect"

//      ┌─── Effect<number, string[], never>
//      ▼
const program = Effect.validateFirst([1, 2, 3, 4, 5], (n) => {
  if (n < 4) {
    return Effect.fail(`${n} is not less that 4`)
  } else {
    return Console.log(`item ${n}`).pipe(Effect.as(n))
  }
})

Effect.runPromise(program).then(console.log, console.error)
// Output:
// item 4
// 4

See

• validateAll for a similar function that accumulates all results.
• firstSuccessOf for a similar function that processes multiple effects and returns the first successful one or the last error.

Signature

declare const validateFirst: { <A, B, E, R>(f: (a: A, i: number) => Effect<B, E, R>, options?: { readonly concurrency?: Concurrency | undefined; readonly batching?: boolean | "inherit" | undefined; readonly concurrentFinalizers?: boolean | undefined; } | undefined): (elements: Iterable<A>) => Effect<B, Array<E>, R>; <A, B, E, R>(elements: Iterable<A>, f: (a: A, i: number) => Effect<B, E, R>, options?: { readonly concurrency?: Concurrency | undefined; readonly batching?: boolean | "inherit" | undefined; readonly concurrentFinalizers?: boolean | undefined; } | undefined): Effect<B, Array<E>, R>; }

Source

Since v2.0.0