Refactoring Service Implementations Outside Layer Definitions

const DatabaseLive = Layer.effect(
  Database,
  Effect.gen(function* () {

    const config = yield* Config
    const logger = yield* Logger

    return {
      query: (sql: string) =>
        Effect.gen(function* () {
          yield* logger.log(`Executing query: ${sql}`)
          const { connection } = yield* config.getConfig
          return { result: `Results from ${connection}` }
        })
    }

  })
)

// Implementation functions might live in different files
const queryLive = (sql: string) =>
  Effect.gen(function* () {
    const config = yield* Config

    const { connection } = yield* config.getConfig
    return { result: `Results from ${connection}` }
  })

// Live layer gets created from the various implementation functions
const DatabaseLive = Layer.effect(
  Database,
  Effect.gen(function* () {
    const config = yield* Config

    return {
      // provideToResultOfFn does not currently exist but would transform
      // queryLive to remove the Requirement from the returned Effect
      query: provideToResultOfFn(Config, queryLive)
    }

  })
)