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Use .provide(layer) to make Effect services available to downstream procedures.
services.ts
import { Effect } from "effect";

export class UsersRepo extends Effect.Service<UsersRepo>()("UsersRepo", {
  accessors: true,
  sync: () => ({
    findById: (id: string) => ({ id, name: "Ada Lovelace" }),
  }),
}) {}
procedure.ts
import { eos } from "effect-orpc";

const effectProcedure = eos.provide(UsersRepo.Default);

const getUser = effectProcedure.effect(function* () {
  return yield* UsersRepo.findById("1");
});

​
Missing services are type errors

If a handler yields a service that was not provided, the procedure should fail to type-check.
missing-service.ts
class MissingRepo extends Context.Tag("MissingRepo")<
  MissingRepo,
  { find: () => Effect.Effect<string> }
>() {}

const procedure = eos.provide(UsersRepo.Default).effect(
  // @ts-expect-error MissingRepo was not provided.
  function* () {
    return yield* MissingRepo;
  },
);

​
Provide multiple services

Merge services into one application layer, then provide that layer once.
app-layer.ts
const AppLive = Layer.mergeAll(UsersRepo.Default, Logger.pretty, Cache.Default);

const effectProcedure = eos.provide(AppLive);

​
Next step

Use request data to provide per-request services in Request-scoped services.
Last modified on June 15, 2026