Fix

src/Layers/express/ExpressApp.ts

@@ -10,9 +10,11 @@ const importExpress = Effect.tryPromise({
     catch: cause => new Error("Could not import 'express'. Make sure it is installed.", { cause }),
 })
 
-export const ExpressAppLive = (config: {
+export const ExpressAppLive = (
+    config: {
         readonly trustProxy?: Config.Config<boolean>
-}) => Layer.effect(ExpressApp, Effect.gen(function*() {
+    } = {}
+) => Layer.effect(ExpressApp, Effect.gen(function*() {
     const app = (yield* importExpress).default()
     app.set("trust proxy", yield* config.trustProxy || Config.succeed(false))
     return app

src/Layers/express/ExpressNodeHTTPServer.ts

@@ -18,7 +18,8 @@ const serverListeningMessage = Match.type<AddressInfo | string | null>().pipe(
     Match.orElse(v => `HTTP server listening on ${ v.address }:${ v.port }`),
 )
 
-export const ExpressNodeHTTPServerLive = (config: {
+export const ExpressNodeHTTPServerLive = (
+    config: {
         readonly backlog?:      Config.Config<number | undefined>
         readonly exclusive?:    Config.Config<boolean | undefined>
         readonly host?:         Config.Config<string | undefined>
@@ -28,7 +29,8 @@ export const ExpressNodeHTTPServerLive = (config: {
         readonly readableAll?:  Config.Config<boolean | undefined>
         readonly signal?:       AbortSignal
         readonly writableAll?:  Config.Config<boolean | undefined>
-}) => Layer.effect(ExpressNodeHTTPServer, Effect.acquireRelease(
+    } = {}
+) => Layer.effect(ExpressNodeHTTPServer, Effect.acquireRelease(
     Effect.gen(function*() {
         const app  = yield* ExpressApp
         const http = yield* importNodeHTTP

src/Layers/express/tests.ts

@@ -0,0 +1,17 @@
+import { Config, Effect, Layer } from "effect"
+import { ExpressAppLive } from "./ExpressApp"
+import { ExpressNodeHTTPServerLive } from "./ExpressNodeHTTPServer"
+
+
+const AppLive = ExpressAppLive()
+const HTTPServerLive = ExpressNodeHTTPServerLive()
+
+const ServerLive = Layer.empty.pipe(
+    Layer.provideMerge(HTTPServerLive),
+    Layer.provideMerge(AppLive),
+)
+
+Layer.launch(ServerLive).pipe(
+    Effect.scoped,
+    Effect.runPromise,
+)