effect-io-ai

Package: effect
Module: Option

Option.partitionMap

Splits an Option into two Options using a function that returns a Result.

When to use

Use when you need to split an optional value into “left” and “right” channels using a Result-returning function.

Details

• None → [None, None]
• Some where f returns Err → [Some(error), None]
• Some where f returns Ok → [None, Some(value)]

Example (Partitioning by Result)

import { Option, Result } from "effect"

const parseNumber = (s: string): Result.Result<number, string> => {
  const n = Number(s)
  return isNaN(n) ? Result.fail("Not a number") : Result.succeed(n)
}

console.log(Option.partitionMap(Option.some("42"), parseNumber))
// Output: [{ _id: 'Option', _tag: 'None' }, { _id: 'Option', _tag: 'Some', value: 42 }]

console.log(Option.partitionMap(Option.some("abc"), parseNumber))
// Output: [{ _id: 'Option', _tag: 'Some', value: 'Not a number' }, { _id: 'Option', _tag: 'None' }]

console.log(Option.partitionMap(Option.none(), parseNumber))
// Output: [{ _id: 'Option', _tag: 'None' }, { _id: 'Option', _tag: 'None' }]

See

• filter for simple predicate-based filtering

Signature

declare const partitionMap: { <A, B, C>(f: (a: A) => Result<C, B>): (self: Option<A>) => [left: Option<B>, right: Option<C>]; <A, B, C>(self: Option<A>, f: (a: A) => Result<C, B>): [left: Option<B>, right: Option<C>]; }

Source

Since v2.0.0