Effect Services

Folder Structure of a repository/service

|- services/
  |- foo-api/
    |- index.ts # entry point for the repo
    |- foo-api.ts
  |- foo-api-service/
    |- index.ts # entry point for the service, exports all
    |- foo-api-service.ts
    |- some-method.ts

"Repositories"

A repository is an abstraction over a service (api, db, etc...).

example, simple API Service

// ./services/foo-api/index.ts
export * from './foo-api';

// ./services/foo-api/foo-api.ts
import axios from 'axios';
import {Context, Effect, Layer, Config, LogLevel, pipe} from 'effect';

export const FOO_API_BASE_URL = pipe(
  Config.nonEmptyString('FOO_API_BASE_URL'),
  // same host used for all environments
  Config.withDefault('https://api.foo.com'),
);
export const FOO_API_TOKEN = Config.nonEmptyString('FOO_API_TOKEN');

export const createFooApi = Effect.gen(function* () {
  const baseURL = yield* FOO_API_BASE_URL;
  const token = yield* FOO_API_TOKEN;

  return axios.create({baseURL, headers: {'X-FOO-TOKEN': token}});
});

export class FooApi extends Context.Tag('FooApi')<
  FooApi,
  Effect.Effect.Success<typeof createFooApi>
>() {
  static Live = Layer.effect(this, createFooApi);
}

"Services"

A service is built on top of a repository (or multiple repositories) and provides Mavely specific functionality.

// ./services/foo-api-service/index.ts
export * from './foo-api-service';

// ./services/foo-api-service/some-method.ts
import {Array, Effect, Schema, Struct, pipe} from 'effect';
import {FooApi} from '../foo-api';

export const someMethod = (entityId: string) =>
  Effect.gen(function* () {
    const prisma = yield* Prisma;
    const fooApi = yield* FooApi;

    return yield* pipe(
      Effect.tryPromise(() => fooApi.get(`/some-endpoint/${entityId}`)),
      Effect.map(Struct.get('data')),
      Effect.flatMap(
        Schema.decodeUnknown(Schema.Struct({result: Struct.String})),
      ),
      Effect.map(Struct.get('result')),
      Effect.flatMap(result => prisma.user.findUnique({where: {id: result}})),
      // do more stuff
    );
  });

// ./services/foo-api-service/foo-api-service.ts
import {Context, Layer} from 'effect';
import {someMethod} from './some-method';

export const createFooApiService = () => ({someMethod});

export class FooApiService extends Context.Tag('FooApiService')<
  FooApiService,
  ReturnType<typeof createFooApiService>
>() {
  static Live = Layer.succeed(this, createFooApiService());
}

TODO: Show using this repo/service from a top level program