effect-io-ai

Package: effect
Module: Option

Option.flatMap

Applies a function that returns an Option to the value of a Some, flattening the result. Returns None if the input is None.

When to use

Use when you need to chain dependent Option computations where each step may return None.

Details

• Some → applies f to the value and returns its Option result
• None → returns None without calling f
• Equivalent to map followed by flatten

Example (Chaining optional lookups)

import { Option } from "effect"

interface User {
  readonly name: string
  readonly address: Option.Option<{ readonly street: Option.Option<string> }>
}

const user: User = {
  name: "John",
  address: Option.some({ street: Option.some("123 Main St") })
}

const street = user.address.pipe(
  Option.flatMap((addr) => addr.street)
)

console.log(street)
// Output: { _id: 'Option', _tag: 'Some', value: '123 Main St' }

See

• map when f returns a plain value
• andThen for a more flexible variant
• flatten to unwrap a nested Option<Option<A>>

Signature

declare const flatMap: { <A, B>(f: (a: A) => Option<B>): (self: Option<A>) => Option<B>; <A, B>(self: Option<A>, f: (a: A) => Option<B>): Option<B>; }

Source

Since v2.0.0