effect-io-ai

Package: effect
Module: Effect

Effect.firstSuccessOf

Runs a sequence of effects and returns the result of the first successful one.

When to use

Use when you have prioritized fallback Effects, such as attempting multiple APIs, reading configuration from several sources, or trying alternative resource locations in order.

Details

This function executes the provided effects in sequence, stopping at the first success. If an effect succeeds, its result is returned immediately and no further effects in the sequence are executed.

If all effects fail, the returned effect fails with the error from the last effect. If the collection is empty, the returned effect defects with an Error whose message is "Received an empty collection of effects".

Example (Trying alternatives until one succeeds)

import { Effect } from "effect"

const primary = Effect.fail("primary unavailable")
const secondary = Effect.succeed("secondary result")
const tertiary = Effect.sync(() => {
  throw new Error("not evaluated")
})

const program = Effect.firstSuccessOf([
  primary,
  secondary,
  tertiary
])

console.log(Effect.runSync(program))
// Output: "secondary result"

Signature

declare const firstSuccessOf: <Eff extends Effect<any, any, any>>(effects: Iterable<Eff>) => Effect<Success<Eff>, Error<Eff>, Services<Eff>>

Source

Since v2.0.0