effect-io-ai

Package: effect
Module: Effect

Effect.provide

Provides necessary dependencies to an effect, removing its environmental requirements.

Details

This function allows you to supply the required environment for an effect. The environment can be provided in the form of one or more Layers, a Context, a Runtime, or a ManagedRuntime. Once the environment is provided, the effect can run without requiring external dependencies.

You can compose layers to create a modular and reusable way of setting up the environment for effects. For example, layers can be used to configure databases, logging services, or any other required dependencies.

Example

import { Context, Effect, Layer } from "effect"

class Database extends Context.Tag("Database")<
  Database,
  { readonly query: (sql: string) => Effect.Effect<Array<unknown>> }
>() {}

const DatabaseLive = Layer.succeed(
  Database,
  {
    // Simulate a database query
    query: (sql: string) => Effect.log(`Executing query: ${sql}`).pipe(Effect.as([]))
  }
)

//      ┌─── Effect<unknown[], never, Database>
//      ▼
const program = Effect.gen(function*() {
  const database = yield* Database
  const result = yield* database.query("SELECT * FROM users")
  return result
})

//      ┌─── Effect<unknown[], never, never>
//      ▼
const runnable = Effect.provide(program, DatabaseLive)

Effect.runPromise(runnable).then(console.log)
// Output:
// timestamp=... level=INFO fiber=#0 message="Executing query: SELECT * FROM users"
// []

See

• provideService for providing a service to an effect.

Signature

declare const provide: { <const Layers extends readonly [Layer.Layer.Any, ...Array<Layer.Layer.Any>]>(layers: Layers): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E | { [k in keyof Layers]: Layer.Layer.Error<Layers[k]>; }[number], { [k in keyof Layers]: Layer.Layer.Context<Layers[k]>; }[number] | Exclude<R, { [k in keyof Layers]: Layer.Layer.Success<Layers[k]>; }[number]>>; <ROut, E2, RIn>(layer: Layer.Layer<ROut, E2, RIn>): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E | E2, RIn | Exclude<R, ROut>>; <R2>(context: Context.Context<R2>): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, R2>>; <R2>(runtime: Runtime.Runtime<R2>): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E, Exclude<R, R2>>; <E2, R2>(managedRuntime: ManagedRuntime.ManagedRuntime<R2, E2>): <A, E, R>(self: Effect<A, E, R>) => Effect<A, E | E2, Exclude<R, R2>>; <A, E, R, const Layers extends readonly [Layer.Layer.Any, ...Array<Layer.Layer.Any>]>(self: Effect<A, E, R>, layers: Layers): Effect<A, E | { [k in keyof Layers]: Layer.Layer.Error<Layers[k]>; }[number], { [k in keyof Layers]: Layer.Layer.Context<Layers[k]>; }[number] | Exclude<R, { [k in keyof Layers]: Layer.Layer.Success<Layers[k]>; }[number]>>; <A, E, R, ROut, E2, RIn>(self: Effect<A, E, R>, layer: Layer.Layer<ROut, E2, RIn>): Effect<A, E | E2, RIn | Exclude<R, ROut>>; <A, E, R, R2>(self: Effect<A, E, R>, context: Context.Context<R2>): Effect<A, E, Exclude<R, R2>>; <A, E, R, R2>(self: Effect<A, E, R>, runtime: Runtime.Runtime<R2>): Effect<A, E, Exclude<R, R2>>; <A, E, E2, R, R2>(self: Effect<A, E, R>, runtime: ManagedRuntime.ManagedRuntime<R2, E2>): Effect<A, E | E2, Exclude<R, R2>>; }

Source

Since v2.0.0