effect-io-ai

Package: effect
Module: Result

Result.flatMap

Chains a function that returns a Result onto a successful value.

When to use

Use to sequence Result-returning computations that should short-circuit on failure.

Details

• If self is a Success, applies f to the value and returns the resulting Result
• If self is a Failure, short-circuits and returns it unchanged
• The error types are merged into a union (E | E2)
• This is the monadic bind / >>= for Result

Example (Validating sequentially)

import { pipe, Result } from "effect"

const result = pipe(
  Result.succeed(5),
  Result.flatMap((n) =>
    n > 0 ? Result.succeed(n * 2) : Result.fail("not positive")
  )
)
console.log(result)
// Output: { _tag: "Success", success: 10, ... }

See

• andThen for a more flexible variant that also accepts plain values
• map when f does not return a Result

Signature

declare const flatMap: { <A, A2, E2>(f: (a: A) => Result<A2, E2>): <E>(self: Result<A, E>) => Result<A2, E | E2>; <A, E, A2, E2>(self: Result<A, E>, f: (a: A) => Result<A2, E2>): Result<A2, E | E2>; }

Source

Since v2.0.0