effect-io-ai

Package: effect
Module: Option

Option.let

Adds a computed plain value to the do notation record.

When to use

Use when you need to bind a derived non-Option value in an Option do notation pipeline.

Example (Adding a computed value)

import { Option, pipe } from "effect"
import * as assert from "node:assert"

const result = pipe(
  Option.Do,
  Option.bind("x", () => Option.some(2)),
  Option.bind("y", () => Option.some(3)),
  Option.let("sum", ({ x, y }) => x + y)
)
assert.deepStrictEqual(result, Option.some({ x: 2, y: 3, sum: 5 }))

See

• Do for starting the chain
• bind to add Option values
• bindTo to start by naming an existing Option

Signature

declare const let: { <N extends string, A extends object, B>(name: Exclude<N, keyof A>, f: (a: NoInfer<A>) => B): (self: Option<A>) => Option<{ [K in N | keyof A]: K extends keyof A ? A[K] : B; }>; <A extends object, N extends string, B>(self: Option<A>, name: Exclude<N, keyof A>, f: (a: NoInfer<A>) => B): Option<{ [K in N | keyof A]: K extends keyof A ? A[K] : B; }>; }

Source

Since v2.0.0