effect-io-ai

Package: effect
Module: Effect

Effect.let

The “do simulation” in Effect allows you to write code in a more declarative style, similar to the “do notation” in other programming languages. It provides a way to define variables and perform operations on them using functions like bind and let.

Here’s how the do simulation works:

1. Start the do simulation using the Do value
2. Within the do simulation scope, you can use the bind function to define variables and bind them to Effect values
3. You can accumulate multiple bind statements to define multiple variables within the scope
4. Inside the do simulation scope, you can also use the let function to define variables and bind them to simple values

Example

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

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

See

• Do
• bind
• bindTo

Signature

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

Source

Since v2.0.0