use-pattern.ts

import { Data, Effect, Layer, ServiceMap } from "effect"

// third party API
const ThirdPartyApi = {
    methodA: () => Promise.resolve(1),
    methodB: (arg: number) => Promise.resolve(arg * 2),
}

interface ThirdPartyApi { methodA: () => Promise<number>; methodB: (arg: number) => Promise<number> }

// wrapper
class ThirdPartyApiClientError extends Data.TaggedError("ThirdPartyApiClientError")<{
    cause: unknown
}> { }

class ThirdPartyApiClient extends ServiceMap.Service<
    ThirdPartyApiClient,
    {
        readonly use: <A>(fn: (_: ThirdPartyApi) => Promise<A>) => Effect.Effect<A, ThirdPartyApiClientError>
    }
>()("ThirdPartyApiClient") {
    static layer = (impl: ThirdPartyApi) => Layer.succeed(this, {
        use: cb => Effect.tryPromise({
            try: () => cb(impl),
            catch: error => new ThirdPartyApiClientError({ cause: error })
        })
    })
}

const program = Effect.gen(function* () {
    const api = yield* ThirdPartyApiClient
    const result = yield* api.use(_ => _.methodB(42))
    console.log(result)
})

program.pipe(Effect.provide(ThirdPartyApiClient.layer(ThirdPartyApi)), Effect.runPromise)