Switch HTTP server API to RequestContext receivers

docs/lyng.io.http.server.md

@@ -43,23 +43,52 @@ suspend fun bootstrapHttpServer() {
 import lyng.io.http.server
 
 val server = HttpServer()
-server.get("/hello") { ex ->
+server.get("/hello") {
-    ex.setHeader("Content-Type", "text/plain")
+    setHeader("Content-Type", "text/plain")
-    ex.respondText(200, "hello")
+    respondText(200, "hello")
 }
 server.listen(8080, "127.0.0.1")
 ```
 
 ---
 
+#### Reusable routers
+
+`Router` collects the same route kinds as `HttpServer`, but does not listen on sockets by itself.  
+Mount it into `HttpServer` or another `Router`.
+
+```lyng
+import lyng.io.http.server
+
+val api = Router()
+api.get("/health") {
+    respondText(200, "ok")
+}
+
+val users = Router()
+users.getPath("/users/{id}") {
+    respondJson({ id: routeParams["id"] })
+}
+
+api.mount(users)
+
+val server = HttpServer()
+server.mount(api)
+server.listen(8080, "127.0.0.1")
+```
+
+Mounted routers reuse the built-in server router. They are configuration-time composition, not an extra per-request Lyng dispatch layer.
+
+---
+
 #### Regex route
 
 Regex routes match the whole request path, not a substring.
 
 ```lyng
-server.get("^/users/([0-9]+)/posts/([0-9]+)$".re) { ex ->
+server.get("^/users/([0-9]+)/posts/([0-9]+)$".re) {
-    val m = ex.routeMatch!!
+    val m = routeMatch!!
-    ex.respondText(200, "user=" + m[1] + ", post=" + m[2])
+    respondText(200, "user=" + m[1] + ", post=" + m[2])
 }
 ```
 
@@ -70,10 +99,10 @@ server.get("^/users/([0-9]+)/posts/([0-9]+)$".re) { ex ->
 Path templates are sugar on top of regex routes. Template parameters are exposed as decoded `routeParams`.
 
 ```lyng
-server.getPath("/users/{userId}/posts/{postId}") { ex ->
+server.getPath("/users/{userId}/posts/{postId}") {
-    ex.respondText(
+    respondText(
         200,
-        ex.routeParams["userId"] + ":" + ex.routeParams["postId"]
+        routeParams["userId"] + ":" + routeParams["postId"]
     )
 }
 ```
@@ -104,7 +133,7 @@ Template rules:
 - `headers: HttpHeaders`
 - `body: Buffer`
 
-`ServerExchange` exposes routing context and response controls:
+`RequestContext` exposes routing context and response controls:
 
 - `request: ServerRequest`
 - `routeMatch: RegexMatch?`
@@ -125,7 +154,7 @@ For path-template routes, both `routeMatch` and `routeParams` are set.
 
 #### JSON request/response helpers
 
-For ordinary HTTP JSON APIs, `ServerExchange` includes two helpers:
+For ordinary HTTP JSON APIs, `RequestContext` includes two helpers:
 
 - `jsonBody<T>()` decodes the request body with typed `Json.decodeAs(...)`
 - `respondJson(body, status = 200)` sets JSON content type and responds with plain `toJsonString()`
@@ -140,15 +169,15 @@ closed class CreateUserResponse(id: Int, name: String, age: Int)
 
 val server = HttpServer()
 
-server.postPath("/api/users") { ex ->
+server.postPath("/api/users") {
-    val req = ex.jsonBody<CreateUserRequest>()
+    val req = jsonBody<CreateUserRequest>()
 
     if (req.name.isBlank()) {
-        ex.respondJson({ error: "name must not be empty" }, 400)
+        respondJson({ error: "name must not be empty" }, 400)
         return
     }
 
-    ex.respondJson(CreateUserResponse(101, req.name, req.age), 201)
+    respondJson(CreateUserResponse(101, req.name, req.age), 201)
 }
 
 server.listen(8080, "127.0.0.1")
@@ -177,13 +206,13 @@ This means exact routes stay fast and always win over template or regex routes f
 You can route websocket upgrades by exact path, regex, or path template:
 
 ```lyng
-server.ws("/chat") { ws, ex ->
+server.ws("/chat") { ws ->
     ws.sendText("hello")
     ws.close()
 }
 
-server.wsPath("/ws/{room}") { ws, ex ->
+server.wsPath("/ws/{room}") { ws ->
-    ws.sendText("room=" + ex.routeParams["room"])
+    ws.sendText("room=" + routeParams["room"])
     ws.close()
 }
 ```
@@ -192,6 +221,23 @@ server.wsPath("/ws/{room}") { ws, ex ->
 
 #### API surface
 
+`Router` route registration methods:
+
+- `get(path: String|Regex, handler)`
+- `getPath(pathTemplate: String, handler)`
+- `post(path: String|Regex, handler)`
+- `postPath(pathTemplate: String, handler)`
+- `put(path: String|Regex, handler)`
+- `putPath(pathTemplate: String, handler)`
+- `delete(path: String|Regex, handler)`
+- `deletePath(pathTemplate: String, handler)`
+- `any(path: String|Regex, handler)`
+- `anyPath(pathTemplate: String, handler)`
+- `ws(path: String|Regex, handler)`
+- `wsPath(pathTemplate: String, handler)`
+- `fallback(handler)`
+- `mount(router)`
+
 `HttpServer` route registration methods:
 
 - `get(path: String|Regex, handler)`
@@ -207,4 +253,5 @@ server.wsPath("/ws/{room}") { ws, ex ->
 - `ws(path: String|Regex, handler)`
 - `wsPath(pathTemplate: String, handler)`
 - `fallback(handler)`
+- `mount(router)`
 - `listen(port, host = null, backlog = 128)`

docs/lyngio.md

@@ -17,7 +17,7 @@
 - **[lyng.io.process](lyng.io.process.md):** External process execution and shell commands. Provides `Process`, `RunningProcess`, and `Platform` information.
 - **[lyng.io.console](lyng.io.console.md):** Rich console/TTY access. Provides `Console` capability detection, geometry, output, and iterable events.
 - **[lyng.io.http](lyng.io.http.md):** HTTP/HTTPS client access. Provides `Http`, `HttpRequest`, `HttpResponse`, and `HttpHeaders`.
-- **[lyng.io.http.server](lyng.io.http.server.md):** Minimal HTTP/1.1 and WebSocket server. Provides `HttpServer`, `ServerRequest`, `ServerExchange`, and `ServerWebSocket`.
+- **[lyng.io.http.server](lyng.io.http.server.md):** Minimal HTTP/1.1 and WebSocket server. Provides `HttpServer`, `Router`, `ServerRequest`, `RequestContext`, and `ServerWebSocket`.
 - **[lyng.io.ws](lyng.io.ws.md):** WebSocket client access. Provides `Ws`, `WsSession`, and `WsMessage`.
 - **[lyng.io.net](lyng.io.net.md):** Transport networking. Provides `Net`, `TcpSocket`, `TcpServer`, `UdpSocket`, and `SocketAddress`.
 - **Shared networking type packages:** `lyng.io.http.types`, `lyng.io.ws.types`, and `lyng.io.net.types` expose reusable value types such as `HttpHeaders`, `WsMessage`, `IpVersion`, `SocketAddress`, and `Datagram` when host code wants type-only imports without installing the corresponding capability object module.

lyngio/src/commonMain/kotlin/net/sergeych/lyng/io/http/server/LyngHttpServerModule.kt

@@ -6,6 +6,7 @@ import net.sergeych.lyng.Scope
 import net.sergeych.lyng.ScopeFacade
 import net.sergeych.lyng.Source
 import net.sergeych.lyng.Arguments
+import net.sergeych.lyng.CallSignature
 import net.sergeych.lyng.TypeDecl
 import net.sergeych.lyng.asFacade
 import net.sergeych.lyng.obj.Obj
@@ -70,14 +71,15 @@ fun createHttpServer(policy: NetAccessPolicy, manager: ImportManager): Boolean =
 
 private suspend fun buildHttpServerModule(module: ModuleScope, policy: NetAccessPolicy) {
     module.eval(Source(HTTP_SERVER_MODULE_NAME, http_serverLyng))
-    val serverExchangeClass = ObjServerExchange.type(module.requireClass("ServerExchange"))
+    val requestContextClass = ObjServerExchange.type(module.requireClass("RequestContext"))
     module.addConst("HttpHeaders", ObjHttpHeaders.type)
     module.addConst("WsMessage", ObjWsMessage.type)
     module.addConst("ServerRequest", ObjServerRequest.type)
-    module.addConst("ServerExchange", serverExchangeClass)
+    module.addConst("RequestContext", requestContextClass)
     module.addConst("ServerWebSocket", ObjServerWebSocket.type)
     module.addConst("HttpServerHandle", ObjHttpServerHandle.type)
-    module.addConst("HttpServer", ObjLyngHttpServer.type(policy, serverExchangeClass))
+    module.addConst("Router", ObjLyngRouter.type(requestContextClass))
+    module.addConst("HttpServer", ObjLyngHttpServer.type(policy, requestContextClass))
 }
 
 private suspend inline fun ScopeFacade.httpServerGuard(crossinline block: suspend () -> Obj): Obj {
@@ -104,6 +106,9 @@ private fun captureCallable(scope: Scope, rawCallable: Obj): RegisteredCallable
 private suspend fun RegisteredCallable.call(vararg args: Obj): Obj =
     scope.asFacade().call(callable, Arguments(args.toList()))
 
+private suspend fun RegisteredCallable.callWithReceiver(receiver: Obj, vararg args: Obj): Obj =
+    scope.asFacade().call(callable, Arguments(args.toList()), receiver)
+
 private val stringType = TypeDecl.Simple("String", false)
 private val nullableStringType = TypeDecl.Simple("String", true)
 private val boolType = TypeDecl.Simple("Bool", false)
@@ -115,11 +120,12 @@ private val nullableRegexMatchType = TypeDecl.Simple("RegexMatch", true)
 private val voidType = TypeDecl.Simple("Void", false)
 private val httpHeadersType = TypeDecl.Simple("HttpHeaders", false)
 private val serverRequestType = TypeDecl.Simple("ServerRequest", false)
-private val serverExchangeType = TypeDecl.Simple("ServerExchange", false)
+private val requestContextType = TypeDecl.Simple("RequestContext", false)
 private val serverWebSocketType = TypeDecl.Simple("ServerWebSocket", false)
 private val nullableServerWsMessageType = TypeDecl.Simple("WsMessage", true)
 private val httpServerHandleType = TypeDecl.Simple("HttpServerHandle", false)
 private val httpServerType = TypeDecl.Simple("HttpServer", false)
+private val routerType = TypeDecl.Simple("Router", false)
 private val nullableAnyType = TypeDecl.TypeNullableAny
 
 private fun listType(item: TypeDecl) = TypeDecl.Generic("List", listOf(item), false)
@@ -129,10 +135,17 @@ private fun unionType(vararg options: TypeDecl) = TypeDecl.Union(options.toList(
 private fun fnType(returnType: TypeDecl, vararg params: TypeDecl) =
     TypeDecl.Function(receiver = null, params = params.toList(), returnType = returnType)
 
+private fun receiverFnType(receiver: TypeDecl, returnType: TypeDecl, vararg params: TypeDecl) =
+    TypeDecl.Function(receiver = receiver, params = params.toList(), returnType = returnType)
+
+private fun receiverCallSignature(receiverTypeName: String) =
+    CallSignature(tailBlockReceiverType = receiverTypeName)
+
 private fun bridgeFn(
     owner: ObjClass,
     name: String,
     typeDecl: TypeDecl.Function,
+    callSignature: net.sergeych.lyng.CallSignature? = null,
     code: suspend ScopeFacade.() -> Obj,
 ) {
     owner.createField(
@@ -140,6 +153,7 @@ private fun bridgeFn(
         initialValue = ObjExternCallable.fromBridge { code() },
         type = net.sergeych.lyng.obj.ObjRecord.Type.Fun,
         typeDecl = typeDecl,
+        callSignature = callSignature,
     )
 }
 
@@ -157,10 +171,24 @@ private fun bridgeProperty(
     )
 }
 
-private class ObjLyngHttpServer(
+private fun requireRoutePattern(scope: ScopeFacade, index: Int): RoutePattern = when (val path = scope.args.list.getOrNull(index)) {
-    private val netPolicy: NetAccessPolicy,
+    is ObjString -> {
+        if (!path.value.startsWith('/')) scope.raiseIllegalArgument("path must start with '/'")
+        RoutePattern.Exact(path.value)
+    }
+    is ObjRegex -> RoutePattern.Regex(path)
+    else -> scope.raiseClassCastError("path must be String or Regex")
+}
+
+private fun requirePathTemplate(scope: ScopeFacade, index: Int): String {
+    val template = scope.requiredArg<ObjString>(index).value
+    if (!template.startsWith('/')) scope.raiseIllegalArgument("pathTemplate must start with '/'")
+    return template
+}
+
+private class RouteRegistry(
     private val exchangeClass: ObjClass,
-) : Obj() {
+) {
     private val methodRoutes = linkedMapOf<String, LinkedHashMap<String, RegisteredCallable>>()
     private val methodRegexRoutes = linkedMapOf<String, MutableList<RegisteredRegexRoute>>()
     private val anyRoutes = linkedMapOf<String, RegisteredCallable>()
@@ -168,87 +196,8 @@ private class ObjLyngHttpServer(
     private val wsRoutes = linkedMapOf<String, RegisteredCallable>()
     private val wsRegexRoutes = mutableListOf<RegisteredRegexRoute>()
     private var fallback: RegisteredCallable? = null
-    private var handle: net.sergeych.lyngio.http.server.HttpServer? = null
 
-    override val objClass: ObjClass
+    suspend fun registerRoute(method: String, scope: ScopeFacade) {
-        get() = type(netPolicy, exchangeClass)
-
-    companion object {
-        private val types = mutableMapOf<Pair<NetAccessPolicy, ObjClass>, ObjClass>()
-
-        fun type(netPolicy: NetAccessPolicy, exchangeClass: ObjClass): ObjClass =
-            types.getOrPut(netPolicy to exchangeClass) {
-                object : ObjClass("HttpServer") {
-                    override suspend fun callOn(scope: Scope): Obj {
-                        if (scope.args.list.isNotEmpty()) scope.raiseError("HttpServer() does not accept arguments")
-                        return ObjLyngHttpServer(netPolicy, exchangeClass)
-                    }
-                }.apply {
-                    val routeArgType = unionType(stringType, regexType)
-                    val exchangeHandlerType = fnType(nullableAnyType, serverExchangeType)
-                    val webSocketHandlerType = fnType(nullableAnyType, serverWebSocketType, serverExchangeType)
-
-                    bridgeFn(this, "get", fnType(httpServerType, routeArgType, exchangeHandlerType)) {
-                        thisAs<ObjLyngHttpServer>().registerRoute("GET", this)
-                    }
-                    bridgeFn(this, "getPath", fnType(httpServerType, stringType, exchangeHandlerType)) {
-                        thisAs<ObjLyngHttpServer>().registerTemplateRoute("GET", this)
-                    }
-                    bridgeFn(this, "post", fnType(httpServerType, routeArgType, exchangeHandlerType)) {
-                        thisAs<ObjLyngHttpServer>().registerRoute("POST", this)
-                    }
-                    bridgeFn(this, "postPath", fnType(httpServerType, stringType, exchangeHandlerType)) {
-                        thisAs<ObjLyngHttpServer>().registerTemplateRoute("POST", this)
-                    }
-                    bridgeFn(this, "put", fnType(httpServerType, routeArgType, exchangeHandlerType)) {
-                        thisAs<ObjLyngHttpServer>().registerRoute("PUT", this)
-                    }
-                    bridgeFn(this, "putPath", fnType(httpServerType, stringType, exchangeHandlerType)) {
-                        thisAs<ObjLyngHttpServer>().registerTemplateRoute("PUT", this)
-                    }
-                    bridgeFn(this, "delete", fnType(httpServerType, routeArgType, exchangeHandlerType)) {
-                        thisAs<ObjLyngHttpServer>().registerRoute("DELETE", this)
-                    }
-                    bridgeFn(this, "deletePath", fnType(httpServerType, stringType, exchangeHandlerType)) {
-                        thisAs<ObjLyngHttpServer>().registerTemplateRoute("DELETE", this)
-                    }
-                    bridgeFn(this, "any", fnType(httpServerType, routeArgType, exchangeHandlerType)) {
-                        thisAs<ObjLyngHttpServer>().registerAny(this)
-                    }
-                    bridgeFn(this, "anyPath", fnType(httpServerType, stringType, exchangeHandlerType)) {
-                        thisAs<ObjLyngHttpServer>().registerTemplateAny(this)
-                    }
-                    bridgeFn(this, "ws", fnType(httpServerType, routeArgType, webSocketHandlerType)) {
-                        thisAs<ObjLyngHttpServer>().registerWs(this)
-                    }
-                    bridgeFn(this, "wsPath", fnType(httpServerType, stringType, webSocketHandlerType)) {
-                        thisAs<ObjLyngHttpServer>().registerTemplateWs(this)
-                    }
-                    bridgeFn(this, "fallback", fnType(httpServerType, exchangeHandlerType)) {
-                        thisAs<ObjLyngHttpServer>().registerFallback(this)
-                    }
-                    bridgeFn(this, "listen", fnType(httpServerHandleType, intType, nullableStringType, intType)) {
-                        thisAs<ObjLyngHttpServer>().listen(this)
-                    }
-                }
-            }
-    }
-
-    private fun ensureMutable(scope: ScopeFacade) {
-        if (handle != null) scope.raiseIllegalState("HttpServer routes cannot be modified after listen()")
-    }
-
-    private fun requireRoutePattern(scope: ScopeFacade, index: Int): RoutePattern = when (val path = scope.args.list.getOrNull(index)) {
-        is ObjString -> {
-            if (!path.value.startsWith('/')) scope.raiseIllegalArgument("path must start with '/'")
-            RoutePattern.Exact(path.value)
-        }
-        is ObjRegex -> RoutePattern.Regex(path)
-        else -> scope.raiseClassCastError("path must be String or Regex")
-    }
-
-    private suspend fun registerRoute(method: String, scope: ScopeFacade): Obj = scope.httpServerGuard {
-        ensureMutable(scope)
         val path = requireRoutePattern(scope, 0)
         val handler = captureCallable(scope.requireScope(), scope.args.list[1])
         when (path) {
@@ -265,11 +214,9 @@ private class ObjLyngHttpServer(
                 routes += RegisteredRegexRoute(path.regex, handler)
             }
         }
-        scope.thisObj
     }
 
-    private suspend fun registerTemplateRoute(method: String, scope: ScopeFacade): Obj = scope.httpServerGuard {
+    suspend fun registerTemplateRoute(method: String, scope: ScopeFacade) {
-        ensureMutable(scope)
         val template = requirePathTemplate(scope, 0)
         val handler = captureCallable(scope.requireScope(), scope.args.list[1])
         val routes = methodRegexRoutes.getOrPut(method) { mutableListOf() }
@@ -278,11 +225,9 @@ private class ObjLyngHttpServer(
             scope.raiseIllegalArgument("duplicate path route for $method $template")
         }
         routes += RegisteredRegexRoute(compiled.pattern, handler, compiled.paramNames, compiled.identity)
-        scope.thisObj
     }
 
-    private suspend fun registerAny(scope: ScopeFacade): Obj = scope.httpServerGuard {
+    suspend fun registerAny(scope: ScopeFacade) {
-        ensureMutable(scope)
         val path = requireRoutePattern(scope, 0)
         val handler = captureCallable(scope.requireScope(), scope.args.list[1])
         when (path) {
@@ -297,11 +242,9 @@ private class ObjLyngHttpServer(
                 anyRegexRoutes += RegisteredRegexRoute(path.regex, handler)
             }
         }
-        scope.thisObj
     }
 
-    private suspend fun registerTemplateAny(scope: ScopeFacade): Obj = scope.httpServerGuard {
+    suspend fun registerTemplateAny(scope: ScopeFacade) {
-        ensureMutable(scope)
         val template = requirePathTemplate(scope, 0)
         val handler = captureCallable(scope.requireScope(), scope.args.list[1])
         val compiled = compilePathTemplate(template, scope)
@@ -309,11 +252,9 @@ private class ObjLyngHttpServer(
             scope.raiseIllegalArgument("duplicate path route for ANY $template")
         }
         anyRegexRoutes += RegisteredRegexRoute(compiled.pattern, handler, compiled.paramNames, compiled.identity)
-        scope.thisObj
     }
 
-    private suspend fun registerWs(scope: ScopeFacade): Obj = scope.httpServerGuard {
+    suspend fun registerWs(scope: ScopeFacade) {
-        ensureMutable(scope)
         val path = requireRoutePattern(scope, 0)
         val handler = captureCallable(scope.requireScope(), scope.args.list[1])
         when (path) {
@@ -328,11 +269,9 @@ private class ObjLyngHttpServer(
                 wsRegexRoutes += RegisteredRegexRoute(path.regex, handler)
             }
         }
-        scope.thisObj
     }
 
-    private suspend fun registerTemplateWs(scope: ScopeFacade): Obj = scope.httpServerGuard {
+    suspend fun registerTemplateWs(scope: ScopeFacade) {
-        ensureMutable(scope)
         val template = requirePathTemplate(scope, 0)
         val handler = captureCallable(scope.requireScope(), scope.args.list[1])
         val compiled = compilePathTemplate(template, scope)
@@ -340,51 +279,68 @@ private class ObjLyngHttpServer(
             scope.raiseIllegalArgument("duplicate websocket path route for $template")
         }
         wsRegexRoutes += RegisteredRegexRoute(compiled.pattern, handler, compiled.paramNames, compiled.identity)
-        scope.thisObj
     }
 
-    private suspend fun registerFallback(scope: ScopeFacade): Obj = scope.httpServerGuard {
+    suspend fun registerFallback(scope: ScopeFacade) {
-        ensureMutable(scope)
         fallback = captureCallable(scope.requireScope(), scope.args.list[0])
-        scope.thisObj
     }
 
-    private fun requirePathTemplate(scope: ScopeFacade, index: Int): String {
+    fun mount(scope: ScopeFacade, other: RouteRegistry) {
-        val template = scope.requiredArg<ObjString>(index).value
+        other.methodRoutes.forEach { (method, routes) ->
-        if (!template.startsWith('/')) scope.raiseIllegalArgument("pathTemplate must start with '/'")
+            val target = methodRoutes.getOrPut(method) { linkedMapOf() }
-        return template
+            routes.forEach { (path, handler) ->
+                if (target.containsKey(path)) scope.raiseIllegalArgument("duplicate route for $method $path")
+                target[path] = handler
+            }
+        }
+        other.methodRegexRoutes.forEach { (method, routes) ->
+            val target = methodRegexRoutes.getOrPut(method) { mutableListOf() }
+            routes.forEach { route ->
+                if (target.any { it.identity == route.identity }) {
+                    scope.raiseIllegalArgument("duplicate route for $method ${route.identity.removePrefix("path:")}")
+                }
+                target += route
+            }
+        }
+        other.anyRoutes.forEach { (path, handler) ->
+            if (anyRoutes.containsKey(path)) scope.raiseIllegalArgument("duplicate route for ANY $path")
+            anyRoutes[path] = handler
+        }
+        other.anyRegexRoutes.forEach { route ->
+            if (anyRegexRoutes.any { it.identity == route.identity }) {
+                scope.raiseIllegalArgument("duplicate route for ANY ${route.identity.removePrefix("path:")}")
+            }
+            anyRegexRoutes += route
+        }
+        other.wsRoutes.forEach { (path, handler) ->
+            if (wsRoutes.containsKey(path)) scope.raiseIllegalArgument("duplicate websocket route for $path")
+            wsRoutes[path] = handler
+        }
+        other.wsRegexRoutes.forEach { route ->
+            if (wsRegexRoutes.any { it.identity == route.identity }) {
+                scope.raiseIllegalArgument("duplicate websocket route for ${route.identity.removePrefix("path:")}")
+            }
+            wsRegexRoutes += route
+        }
+        if (other.fallback != null) {
+            if (fallback != null) scope.raiseIllegalArgument("fallback is already defined")
+            fallback = other.fallback
+        }
     }
 
-    private suspend fun listen(scope: ScopeFacade): Obj = scope.httpServerGuard {
+    suspend fun dispatchRequest(request: HttpRequest): HttpHandlerResult {
-        ensureMutable(scope)
-        val port = scope.requiredArg<ObjInt>(0).value.toInt()
-        val host = scope.args.list.getOrNull(1)?.let { objOrNullToString(scope, it, "host") }
-        val backlog = scope.args.list.getOrNull(2)?.let { objToInt(scope, it, "backlog") } ?: 128
-        if (port !in 0..65535) scope.raiseIllegalArgument("port must be in 0..65535")
-        if (backlog <= 0) scope.raiseIllegalArgument("backlog must be positive")
-        netPolicy.require(NetAccessOp.TcpListen(host, port, backlog))
-        val started = startHttpServer(
-            config = HttpServerConfig(host = host ?: "127.0.0.1", port = port, backlog = backlog),
-        ) { request ->
-            dispatchRequest(request)
-        }
-        handle = started
-        ObjHttpServerHandle(started)
-    }
-
-    private suspend fun dispatchRequest(request: HttpRequest): HttpHandlerResult {
         val path = request.head.path
         if (request.head.wantsWebSocketUpgrade) {
             wsRoutes[path]?.let { route ->
                 return HttpHandlerResult.WebSocket { session ->
                     val exchange = ObjServerExchange(request, null, emptyMap(), exchangeClass)
-                    route.call(ObjServerWebSocket(session), exchange)
+                    route.callWithReceiver(exchange, ObjServerWebSocket(session))
                 }
             }
             matchRegexRoute(wsRegexRoutes, path)?.let { matched ->
                 return HttpHandlerResult.WebSocket { session ->
                     val exchange = ObjServerExchange(request, ObjRegexMatch(matched.match), matched.params, exchangeClass)
-                    matched.handler.call(ObjServerWebSocket(session), exchange)
+                    matched.handler.callWithReceiver(exchange, ObjServerWebSocket(session))
                 }
             }
         }
@@ -393,19 +349,19 @@ private class ObjLyngHttpServer(
         val exactRoute = methodRoutes[method]?.get(path) ?: anyRoutes[path]
         if (exactRoute != null) {
             val exchange = ObjServerExchange(request, null, emptyMap(), exchangeClass)
-            exactRoute.call(exchange)
+            exactRoute.callWithReceiver(exchange)
             return exchangeResult(exactRoute === fallback, exchange)
         }
 
         matchRegexRoute(methodRegexRoutes[method], path)?.let { matched ->
             val exchange = ObjServerExchange(request, ObjRegexMatch(matched.match), matched.params, exchangeClass)
-            matched.handler.call(exchange)
+            matched.handler.callWithReceiver(exchange)
             return exchangeResult(false, exchange)
         }
 
         matchRegexRoute(anyRegexRoutes, path)?.let { matched ->
             val exchange = ObjServerExchange(request, ObjRegexMatch(matched.match), matched.params, exchangeClass)
-            matched.handler.call(exchange)
+            matched.handler.callWithReceiver(exchange)
             return exchangeResult(false, exchange)
         }
 
@@ -413,7 +369,7 @@ private class ObjLyngHttpServer(
             HttpResponse(status = 404, body = "not found".encodeToByteArray())
         )
         val exchange = ObjServerExchange(request, null, emptyMap(), exchangeClass)
-        fallbackRoute.call(exchange)
+        fallbackRoute.callWithReceiver(exchange)
         return exchangeResult(true, exchange)
     }
 
@@ -430,6 +386,262 @@ private class ObjLyngHttpServer(
     }
 }
 
+private class ObjLyngHttpServer(
+    private val netPolicy: NetAccessPolicy,
+    private val requestContextClass: ObjClass,
+) : Obj() {
+    private val routes = RouteRegistry(requestContextClass)
+    private var handle: net.sergeych.lyngio.http.server.HttpServer? = null
+
+    override val objClass: ObjClass
+        get() = type(netPolicy, requestContextClass)
+
+    companion object {
+        private val types = mutableMapOf<Pair<NetAccessPolicy, ObjClass>, ObjClass>()
+
+        fun type(netPolicy: NetAccessPolicy, requestContextClass: ObjClass): ObjClass =
+            types.getOrPut(netPolicy to requestContextClass) {
+                object : ObjClass("HttpServer") {
+                    override suspend fun callOn(scope: Scope): Obj {
+                        if (scope.args.list.isNotEmpty()) scope.raiseError("HttpServer() does not accept arguments")
+                        return ObjLyngHttpServer(netPolicy, requestContextClass)
+                    }
+                }.apply {
+                    val routeArgType = unionType(stringType, regexType)
+                    val exchangeHandlerType = receiverFnType(requestContextType, nullableAnyType)
+                    val webSocketHandlerType = receiverFnType(requestContextType, nullableAnyType, serverWebSocketType)
+                    val exchangeHandlerSignature = receiverCallSignature("RequestContext")
+
+                    bridgeFn(this, "get", fnType(httpServerType, routeArgType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngHttpServer>().registerRoute("GET", this)
+                    }
+                    bridgeFn(this, "getPath", fnType(httpServerType, stringType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngHttpServer>().registerTemplateRoute("GET", this)
+                    }
+                    bridgeFn(this, "post", fnType(httpServerType, routeArgType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngHttpServer>().registerRoute("POST", this)
+                    }
+                    bridgeFn(this, "postPath", fnType(httpServerType, stringType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngHttpServer>().registerTemplateRoute("POST", this)
+                    }
+                    bridgeFn(this, "put", fnType(httpServerType, routeArgType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngHttpServer>().registerRoute("PUT", this)
+                    }
+                    bridgeFn(this, "putPath", fnType(httpServerType, stringType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngHttpServer>().registerTemplateRoute("PUT", this)
+                    }
+                    bridgeFn(this, "delete", fnType(httpServerType, routeArgType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngHttpServer>().registerRoute("DELETE", this)
+                    }
+                    bridgeFn(this, "deletePath", fnType(httpServerType, stringType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngHttpServer>().registerTemplateRoute("DELETE", this)
+                    }
+                    bridgeFn(this, "any", fnType(httpServerType, routeArgType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngHttpServer>().registerAny(this)
+                    }
+                    bridgeFn(this, "anyPath", fnType(httpServerType, stringType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngHttpServer>().registerTemplateAny(this)
+                    }
+                    bridgeFn(this, "ws", fnType(httpServerType, routeArgType, webSocketHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngHttpServer>().registerWs(this)
+                    }
+                    bridgeFn(this, "wsPath", fnType(httpServerType, stringType, webSocketHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngHttpServer>().registerTemplateWs(this)
+                    }
+                    bridgeFn(this, "fallback", fnType(httpServerType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngHttpServer>().registerFallback(this)
+                    }
+                    bridgeFn(this, "mount", fnType(httpServerType, routerType)) {
+                        thisAs<ObjLyngHttpServer>().mount(this)
+                    }
+                    bridgeFn(this, "listen", fnType(httpServerHandleType, intType, nullableStringType, intType)) {
+                        thisAs<ObjLyngHttpServer>().listen(this)
+                    }
+                }
+            }
+    }
+
+    private fun ensureMutable(scope: ScopeFacade) {
+        if (handle != null) scope.raiseIllegalState("HttpServer routes cannot be modified after listen()")
+    }
+
+    private suspend fun registerRoute(method: String, scope: ScopeFacade): Obj = scope.httpServerGuard {
+        ensureMutable(scope)
+        routes.registerRoute(method, scope)
+        scope.thisObj
+    }
+
+    private suspend fun registerTemplateRoute(method: String, scope: ScopeFacade): Obj = scope.httpServerGuard {
+        ensureMutable(scope)
+        routes.registerTemplateRoute(method, scope)
+        scope.thisObj
+    }
+
+    private suspend fun registerAny(scope: ScopeFacade): Obj = scope.httpServerGuard {
+        ensureMutable(scope)
+        routes.registerAny(scope)
+        scope.thisObj
+    }
+
+    private suspend fun registerTemplateAny(scope: ScopeFacade): Obj = scope.httpServerGuard {
+        ensureMutable(scope)
+        routes.registerTemplateAny(scope)
+        scope.thisObj
+    }
+
+    private suspend fun registerWs(scope: ScopeFacade): Obj = scope.httpServerGuard {
+        ensureMutable(scope)
+        routes.registerWs(scope)
+        scope.thisObj
+    }
+
+    private suspend fun registerTemplateWs(scope: ScopeFacade): Obj = scope.httpServerGuard {
+        ensureMutable(scope)
+        routes.registerTemplateWs(scope)
+        scope.thisObj
+    }
+
+    private suspend fun registerFallback(scope: ScopeFacade): Obj = scope.httpServerGuard {
+        ensureMutable(scope)
+        routes.registerFallback(scope)
+        scope.thisObj
+    }
+
+    private suspend fun mount(scope: ScopeFacade): Obj = scope.httpServerGuard {
+        ensureMutable(scope)
+        routes.mount(scope, scope.requiredArg<ObjLyngRouter>(0).routes)
+        scope.thisObj
+    }
+
+    private suspend fun listen(scope: ScopeFacade): Obj = scope.httpServerGuard {
+        ensureMutable(scope)
+        val port = scope.requiredArg<ObjInt>(0).value.toInt()
+        val host = scope.args.list.getOrNull(1)?.let { objOrNullToString(scope, it, "host") }
+        val backlog = scope.args.list.getOrNull(2)?.let { objToInt(scope, it, "backlog") } ?: 128
+        if (port !in 0..65535) scope.raiseIllegalArgument("port must be in 0..65535")
+        if (backlog <= 0) scope.raiseIllegalArgument("backlog must be positive")
+        netPolicy.require(NetAccessOp.TcpListen(host, port, backlog))
+        val started = startHttpServer(
+            config = HttpServerConfig(host = host ?: "127.0.0.1", port = port, backlog = backlog),
+        ) { request ->
+            routes.dispatchRequest(request)
+        }
+        handle = started
+        ObjHttpServerHandle(started)
+    }
+}
+
+private class ObjLyngRouter(
+    private val requestContextClass: ObjClass,
+) : Obj() {
+    val routes = RouteRegistry(requestContextClass)
+
+    override val objClass: ObjClass
+        get() = type(requestContextClass)
+
+    companion object {
+        private val types = mutableMapOf<ObjClass, ObjClass>()
+
+        fun type(requestContextClass: ObjClass): ObjClass =
+            types.getOrPut(requestContextClass) {
+                object : ObjClass("Router") {
+                    override suspend fun callOn(scope: Scope): Obj {
+                        if (scope.args.list.isNotEmpty()) scope.raiseError("Router() does not accept arguments")
+                        return ObjLyngRouter(requestContextClass)
+                    }
+                }.apply {
+                    val routeArgType = unionType(stringType, regexType)
+                    val exchangeHandlerType = receiverFnType(requestContextType, nullableAnyType)
+                    val webSocketHandlerType = receiverFnType(requestContextType, nullableAnyType, serverWebSocketType)
+                    val exchangeHandlerSignature = receiverCallSignature("RequestContext")
+
+                    bridgeFn(this, "get", fnType(routerType, routeArgType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngRouter>().registerRoute("GET", this)
+                    }
+                    bridgeFn(this, "getPath", fnType(routerType, stringType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngRouter>().registerTemplateRoute("GET", this)
+                    }
+                    bridgeFn(this, "post", fnType(routerType, routeArgType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngRouter>().registerRoute("POST", this)
+                    }
+                    bridgeFn(this, "postPath", fnType(routerType, stringType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngRouter>().registerTemplateRoute("POST", this)
+                    }
+                    bridgeFn(this, "put", fnType(routerType, routeArgType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngRouter>().registerRoute("PUT", this)
+                    }
+                    bridgeFn(this, "putPath", fnType(routerType, stringType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngRouter>().registerTemplateRoute("PUT", this)
+                    }
+                    bridgeFn(this, "delete", fnType(routerType, routeArgType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngRouter>().registerRoute("DELETE", this)
+                    }
+                    bridgeFn(this, "deletePath", fnType(routerType, stringType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngRouter>().registerTemplateRoute("DELETE", this)
+                    }
+                    bridgeFn(this, "any", fnType(routerType, routeArgType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngRouter>().registerAny(this)
+                    }
+                    bridgeFn(this, "anyPath", fnType(routerType, stringType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngRouter>().registerTemplateAny(this)
+                    }
+                    bridgeFn(this, "ws", fnType(routerType, routeArgType, webSocketHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngRouter>().registerWs(this)
+                    }
+                    bridgeFn(this, "wsPath", fnType(routerType, stringType, webSocketHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngRouter>().registerTemplateWs(this)
+                    }
+                    bridgeFn(this, "fallback", fnType(routerType, exchangeHandlerType), exchangeHandlerSignature) {
+                        thisAs<ObjLyngRouter>().registerFallback(this)
+                    }
+                    bridgeFn(this, "mount", fnType(routerType, routerType)) {
+                        thisAs<ObjLyngRouter>().mount(this)
+                    }
+                }
+            }
+    }
+
+    private suspend fun registerRoute(method: String, scope: ScopeFacade): Obj = scope.httpServerGuard {
+        routes.registerRoute(method, scope)
+        scope.thisObj
+    }
+
+    private suspend fun registerTemplateRoute(method: String, scope: ScopeFacade): Obj = scope.httpServerGuard {
+        routes.registerTemplateRoute(method, scope)
+        scope.thisObj
+    }
+
+    private suspend fun registerAny(scope: ScopeFacade): Obj = scope.httpServerGuard {
+        routes.registerAny(scope)
+        scope.thisObj
+    }
+
+    private suspend fun registerTemplateAny(scope: ScopeFacade): Obj = scope.httpServerGuard {
+        routes.registerTemplateAny(scope)
+        scope.thisObj
+    }
+
+    private suspend fun registerWs(scope: ScopeFacade): Obj = scope.httpServerGuard {
+        routes.registerWs(scope)
+        scope.thisObj
+    }
+
+    private suspend fun registerTemplateWs(scope: ScopeFacade): Obj = scope.httpServerGuard {
+        routes.registerTemplateWs(scope)
+        scope.thisObj
+    }
+
+    private suspend fun registerFallback(scope: ScopeFacade): Obj = scope.httpServerGuard {
+        routes.registerFallback(scope)
+        scope.thisObj
+    }
+
+    private suspend fun mount(scope: ScopeFacade): Obj = scope.httpServerGuard {
+        routes.mount(scope, scope.requiredArg<ObjLyngRouter>(0).routes)
+        scope.thisObj
+    }
+}
+
 private sealed interface RoutePattern {
     data class Exact(val path: String) : RoutePattern
     data class Regex(val regex: ObjRegex) : RoutePattern
@@ -604,9 +816,9 @@ private class ObjServerExchange(
 
         fun type(base: ObjClass): ObjClass =
             types.getOrPut(base) {
-                object : ObjClass("ServerExchange") {
+                object : ObjClass("RequestContext") {
                     override suspend fun callOn(scope: Scope): Obj {
-                        scope.raiseError("ServerExchange cannot be created directly")
+                        scope.raiseError("RequestContext cannot be created directly")
                     }
                 }.apply {
                     bridgeProperty(this, "request", serverRequestType) {
@@ -618,8 +830,11 @@ private class ObjServerExchange(
                     bridgeProperty(this, "routeParams", mapType(stringType, stringType)) {
                         thisAs<ObjServerExchange>().routeParams.toObjMap()
                     }
-                    addFn(
+                    bridgeFn(
+                        this,
                         "jsonBody",
+                        base.getInstanceMemberOrNull("jsonBody")?.typeDecl as? TypeDecl.Function
+                            ?: fnType(nullableAnyType),
                         callSignature = base.getInstanceMemberOrNull("jsonBody")?.callSignature
                     ) {
                         val self = thisAs<ObjServerExchange>()
@@ -641,8 +856,11 @@ private class ObjServerExchange(
                         self.setHttpResponse(status, bodyText.encodeToByteArray())
                         ObjVoid
                     }
-                    addFn(
+                    bridgeFn(
+                        this,
                         "respondJson",
+                        base.getInstanceMemberOrNull("respondJson")?.typeDecl as? TypeDecl.Function
+                            ?: fnType(voidType, nullableAnyType, intType),
                         callSignature = base.getInstanceMemberOrNull("respondJson")?.callSignature
                     ) {
                         val self = thisAs<ObjServerExchange>()
@@ -677,14 +895,15 @@ private class ObjServerExchange(
                     bridgeFn(
                         this,
                         "acceptWebSocket",
-                        fnType(voidType, fnType(nullableAnyType, serverWebSocketType, serverExchangeType))
+                        fnType(voidType, receiverFnType(requestContextType, nullableAnyType, serverWebSocketType)),
+                        receiverCallSignature("RequestContext")
                     ) {
                         val self = thisAs<ObjServerExchange>()
                         val registered = captureCallable(requireScope(), args.list[0])
                         self.ensureMutable(this)
                         self.result = ExchangeResult.WebSocket(
                             HttpHandlerResult.WebSocket { session ->
-                                registered.call(ObjServerWebSocket(session), self)
+                                registered.callWithReceiver(self, ObjServerWebSocket(session))
                             }
                         )
                         ObjVoid

lyngio/src/jvmTest/kotlin/net/sergeych/lyng/io/http/server/LyngHttpServerModuleTest.kt

@@ -51,12 +51,12 @@ class LyngHttpServerModuleTest {
             import lyng.io.http.server
 
             val server = HttpServer()
-            server.get("/hello") { ex ->
+            server.get("/hello") {
-                ex.setHeader("Content-Type", "text/plain")
+                setHeader("Content-Type", "text/plain")
-                ex.respondText(200, "hello from lyng")
+                respondText(200, "hello from lyng")
             }
-            server.fallback { ex ->
+            server.fallback {
-                ex.respondText(404, "miss:" + ex.request.path)
+                respondText(404, "miss:" + request.path)
             }
             server.listen(0, "127.0.0.1")
         """.trimIndent()
@@ -101,11 +101,11 @@ class LyngHttpServerModuleTest {
             import lyng.io.http.server
 
             val server = HttpServer()
-            server.get("/query") { ex ->
+            server.get("/query") {
-                val q = ex.request.query
+                val q = request.query
-                ex.respondText(
+                respondText(
                     200,
-                    (ex.request.queryString ?: "<null>") +
+                    (request.queryString ?: "<null>") +
                         "|" + q.size +
                         "|" + (q["a"] ?: "<null>") +
                         "|" + (q["b"] ?: "<null>") +
@@ -165,20 +165,20 @@ class LyngHttpServerModuleTest {
             import lyng.io.http.server
 
             val server = HttpServer()
-            server.get("^/users/([0-9]+)/posts/([0-9]+)$".re) { ex ->
+            server.get("^/users/([0-9]+)/posts/([0-9]+)$".re) {
-                val m = ex.routeMatch!!
+                val m = routeMatch!!
-                ex.respondText(
+                respondText(
                     200,
                     m[1] +
                         "|" + m[2] +
-                        "|" + ex.request.pathParts[0] +
+                        "|" + request.pathParts[0] +
-                        "," + ex.request.pathParts[1] +
+                        "," + request.pathParts[1] +
-                        "," + ex.request.pathParts[2] +
+                        "," + request.pathParts[2] +
-                        "," + ex.request.pathParts[3]
+                        "," + request.pathParts[3]
                 )
             }
-            server.get("/users/fixed/posts/9") { ex ->
+            server.get("/users/fixed/posts/9") {
-                ex.respondText(200, "fixed|" + (ex.routeMatch == null))
+                respondText(200, "fixed|" + (routeMatch == null))
             }
             server.listen(0, "127.0.0.1")
         """.trimIndent()
@@ -223,17 +223,17 @@ class LyngHttpServerModuleTest {
             import lyng.io.http.server
 
             val server = HttpServer()
-            server.get("/users/fixed/posts/9") { ex ->
+            server.get("/users/fixed/posts/9") {
-                ex.respondText(200, "fixed|" + ex.routeParams.size)
+                respondText(200, "fixed|" + routeParams.size)
             }
-            server.getPath("/users/{userId}/posts/{postId}") { ex ->
+            server.getPath("/users/{userId}/posts/{postId}") {
-                ex.respondText(
+                respondText(
                     200,
-                    ex.routeParams["userId"] + "|" +
+                    routeParams["userId"] + "|" +
-                        ex.routeParams["postId"] + "|" +
+                        routeParams["postId"] + "|" +
-                        ex.request.pathParts[1] + "|" +
+                        request.pathParts[1] + "|" +
-                        ex.request.pathParts[3] + "|" +
+                        request.pathParts[3] + "|" +
-                        (ex.routeMatch != null)
+                        (routeMatch != null)
                 )
             }
             server.listen(0, "127.0.0.1")
@@ -282,9 +282,9 @@ class LyngHttpServerModuleTest {
             closed class CreateUserResponse(id: Int, name: String, age: Int)
 
             val server = HttpServer()
-            server.postPath("/api/users") { ex ->
+            server.postPath("/api/users") {
-                val req = ex.jsonBody<CreateUserRequest>()
+                val req = jsonBody<CreateUserRequest>()
-                ex.respondJson(CreateUserResponse(101, req.name, req.age), 201)
+                respondJson(CreateUserResponse(101, req.name, req.age), 201)
             }
             server.listen(0, "127.0.0.1")
         """.trimIndent()
@@ -315,6 +315,76 @@ class LyngHttpServerModuleTest {
         handle.invokeInstanceMethod(scope, "close")
     }
 
+    @Test
+    fun routerMountPreservesBuiltInRoutingSemantics() = runBlocking {
+        val engine = getSystemNetEngine()
+        if (!engine.isSupported || !engine.isTcpAvailable) return@runBlocking
+
+        val scope = Script.newScope()
+        createHttpServerModule(PermitAllNetAccessPolicy, scope)
+
+        val code = """
+            import lyng.io.http.server
+
+            val api = Router()
+            api.get("/health") {
+                respondText(200, "ok")
+            }
+
+            val users = Router()
+            users.getPath("/users/{id}") {
+                respondText(200, "user:" + routeParams["id"])
+            }
+            users.fallback {
+                respondText(404, "router-miss:" + request.path)
+            }
+
+            api.mount(users)
+
+            val server = HttpServer()
+            server.mount(api)
+            server.listen(0, "127.0.0.1")
+        """.trimIndent()
+
+        val handle = Compiler.compile(code).execute(scope)
+        val port = waitForPort(handle, scope)
+
+        val client = engine.tcpConnect("127.0.0.1", port, 2_000, true)
+        try {
+            client.writeUtf8("GET /health HTTP/1.1\r\nHost: localhost\r\nConnection: close\r\n\r\n")
+            client.flush()
+            val response = readHttpResponse(client)
+            assertTrue(response.contains("200 OK"), response)
+            assertTrue(response.endsWith("ok"), response)
+        } finally {
+            client.close()
+        }
+
+        val client2 = engine.tcpConnect("127.0.0.1", port, 2_000, true)
+        try {
+            client2.writeUtf8("GET /users/alice HTTP/1.1\r\nHost: localhost\r\nConnection: close\r\n\r\n")
+            client2.flush()
+            val response = readHttpResponse(client2)
+            assertTrue(response.contains("200 OK"), response)
+            assertTrue(response.endsWith("user:alice"), response)
+        } finally {
+            client2.close()
+        }
+
+        val client3 = engine.tcpConnect("127.0.0.1", port, 2_000, true)
+        try {
+            client3.writeUtf8("GET /missing HTTP/1.1\r\nHost: localhost\r\nConnection: close\r\n\r\n")
+            client3.flush()
+            val response = readHttpResponse(client3)
+            assertTrue(response.contains("404"), response)
+            assertTrue(response.endsWith("router-miss:/missing"), response)
+        } finally {
+            client3.close()
+        }
+
+        handle.invokeInstanceMethod(scope, "close")
+    }
+
     private suspend fun waitForPort(handle: Obj, scope: net.sergeych.lyng.Scope): Int {
         repeat(100) {
             val port = runCatching {

lyngio/stdlib/lyng/io/http_server.lyng

@@ -28,7 +28,7 @@ extern class ServerWebSocket {
 }
 
 /* Mutable exchange object for one incoming request. */
-extern class ServerExchange {
+extern class RequestContext {
     val request: ServerRequest
     val routeMatch: RegexMatch?
     val routeParams: Map<String, String>
@@ -38,7 +38,7 @@ extern class ServerExchange {
     fun respondJson(body: Object?, status: Int = 200): void
     fun setHeader(name: String, value: String): void
     fun addHeader(name: String, value: String): void
-    fun acceptWebSocket(handler: (ServerWebSocket, ServerExchange) -> Object?): void
+    fun acceptWebSocket(handler: RequestContext.(ServerWebSocket) -> Object?): void
     fun isHandled(): Bool
 }
 
@@ -48,20 +48,39 @@ extern class HttpServerHandle {
     fun close(): void
 }
 
-/* Exact-path HTTP/WebSocket server with built-in router. */
+/* Reusable route collection mounted into HttpServer or other Router. */
+extern class Router {
+    fun get(path: String|Regex, handler: RequestContext.() -> Object?): Router
+    fun getPath(pathTemplate: String, handler: RequestContext.() -> Object?): Router
+    fun post(path: String|Regex, handler: RequestContext.() -> Object?): Router
+    fun postPath(pathTemplate: String, handler: RequestContext.() -> Object?): Router
+    fun put(path: String|Regex, handler: RequestContext.() -> Object?): Router
+    fun putPath(pathTemplate: String, handler: RequestContext.() -> Object?): Router
+    fun delete(path: String|Regex, handler: RequestContext.() -> Object?): Router
+    fun deletePath(pathTemplate: String, handler: RequestContext.() -> Object?): Router
+    fun any(path: String|Regex, handler: RequestContext.() -> Object?): Router
+    fun anyPath(pathTemplate: String, handler: RequestContext.() -> Object?): Router
+    fun ws(path: String|Regex, handler: RequestContext.(ServerWebSocket) -> Object?): Router
+    fun wsPath(pathTemplate: String, handler: RequestContext.(ServerWebSocket) -> Object?): Router
+    fun fallback(handler: RequestContext.() -> Object?): Router
+    fun mount(router: Router): Router
+}
+
+/* HTTP/WebSocket server with built-in router. */
 extern class HttpServer {
-    fun get(path: String|Regex, handler: (ServerExchange) -> Object?): HttpServer
+    fun get(path: String|Regex, handler: RequestContext.() -> Object?): HttpServer
-    fun getPath(pathTemplate: String, handler: (ServerExchange) -> Object?): HttpServer
+    fun getPath(pathTemplate: String, handler: RequestContext.() -> Object?): HttpServer
-    fun post(path: String|Regex, handler: (ServerExchange) -> Object?): HttpServer
+    fun post(path: String|Regex, handler: RequestContext.() -> Object?): HttpServer
-    fun postPath(pathTemplate: String, handler: (ServerExchange) -> Object?): HttpServer
+    fun postPath(pathTemplate: String, handler: RequestContext.() -> Object?): HttpServer
-    fun put(path: String|Regex, handler: (ServerExchange) -> Object?): HttpServer
+    fun put(path: String|Regex, handler: RequestContext.() -> Object?): HttpServer
-    fun putPath(pathTemplate: String, handler: (ServerExchange) -> Object?): HttpServer
+    fun putPath(pathTemplate: String, handler: RequestContext.() -> Object?): HttpServer
-    fun delete(path: String|Regex, handler: (ServerExchange) -> Object?): HttpServer
+    fun delete(path: String|Regex, handler: RequestContext.() -> Object?): HttpServer
-    fun deletePath(pathTemplate: String, handler: (ServerExchange) -> Object?): HttpServer
+    fun deletePath(pathTemplate: String, handler: RequestContext.() -> Object?): HttpServer
-    fun any(path: String|Regex, handler: (ServerExchange) -> Object?): HttpServer
+    fun any(path: String|Regex, handler: RequestContext.() -> Object?): HttpServer
-    fun anyPath(pathTemplate: String, handler: (ServerExchange) -> Object?): HttpServer
+    fun anyPath(pathTemplate: String, handler: RequestContext.() -> Object?): HttpServer
-    fun ws(path: String|Regex, handler: (ServerWebSocket, ServerExchange) -> Object?): HttpServer
+    fun ws(path: String|Regex, handler: RequestContext.(ServerWebSocket) -> Object?): HttpServer
-    fun wsPath(pathTemplate: String, handler: (ServerWebSocket, ServerExchange) -> Object?): HttpServer
+    fun wsPath(pathTemplate: String, handler: RequestContext.(ServerWebSocket) -> Object?): HttpServer
-    fun fallback(handler: (ServerExchange) -> Object?): HttpServer
+    fun fallback(handler: RequestContext.() -> Object?): HttpServer
+    fun mount(router: Router): HttpServer
     fun listen(port: Int, host: String? = null, backlog: Int = 128): HttpServerHandle
 }

lynglib/src/commonMain/kotlin/net/sergeych/lyng/Compiler.kt

@@ -3463,12 +3463,13 @@ class Compiler(
             is FastLocalVarRef -> ref.name
             is LocalSlotRef -> ref.name
             is FieldRef -> ref.name
+            is ImplicitThisMemberRef -> ref.name
             else -> null
         }
         if (name != null) {
             if (lookupGenericFunctionDecl(name) != null) return true
             if (name.firstOrNull()?.isUpperCase() == true) return true
-            return ref is FieldRef
+            return ref is FieldRef || ref is ImplicitThisMemberRef
         }
         return ref is ConstRef && ref.constValue is ObjClass
     }
@@ -3482,6 +3483,13 @@ class Compiler(
         implicitItType: TypeDecl? = null,
         expectedCallableType: TypeDecl.Function? = null
     ): ObjRef {
+        fun receiverTypeName(typeDecl: TypeDecl?): String? = when (typeDecl) {
+            is TypeDecl.Simple -> typeDecl.name
+            is TypeDecl.Generic -> typeDecl.name
+            else -> null
+        }
+
+        val effectiveExpectedReceiverType = expectedReceiverType ?: receiverTypeName(expectedCallableType?.receiver)
         // lambda args are different:
         val startPos = cc.currentPos()
         val label = lastLabel
@@ -3545,7 +3553,13 @@ class Compiler(
         val capturePlan = CapturePlan(paramSlotPlan, isFunction = true, propagateToParentFunction = lambdaDepth > 0)
         capturePlanStack.add(capturePlan)
         val parsedBody = try {
-            inCodeContext(CodeContext.Function("<lambda>", implicitThisMembers = true, implicitThisTypeName = expectedReceiverType)) {
+            inCodeContext(
+                CodeContext.Function(
+                    "<lambda>",
+                    implicitThisMembers = true,
+                    implicitThisTypeName = effectiveExpectedReceiverType
+                )
+            ) {
                 val returnLabels = label?.let { setOf(it) } ?: emptySet()
                 returnLabelStack.addLast(returnLabels)
                 try {
@@ -3798,13 +3812,13 @@ class Compiler(
             inferredReturnClass = returnClass,
             inlineBodyRef = inlineBodyRef,
             supportsDirectInvokeFastPath = supportsDirectInvokeFastPath,
-            preferredThisType = expectedReceiverType,
+            preferredThisType = effectiveExpectedReceiverType,
             wrapAsExtensionCallable = wrapAsExtensionCallable,
             returnLabels = returnLabels,
             pos = startPos
         )
         val lambdaTypeDecl = TypeDecl.Function(
-            receiver = null,
+            receiver = effectiveExpectedReceiverType?.let { TypeDecl.Simple(it, false) },
             params = lambdaParamTypeDecls.toList(),
             returnType = inferredReturnDecl ?: returnClass?.let { TypeDecl.Simple(it.className, false) } ?: TypeDecl.TypeAny,
             nullable = false
@@ -7121,7 +7135,19 @@ class Compiler(
         }
         val result = when (left) {
             is ImplicitThisMemberRef ->
-                if (left.methodId == null && left.fieldId != null) {
+                if (!explicitTypeArgs.isNullOrEmpty()) {
+                    val explicitReceiver: ObjRef = (left.preferredThisTypeName() ?: implicitThisTypeName)
+                        ?.let { QualifiedThisRef(it, left.atPos) }
+                        ?: LocalVarRef("this", left.atPos)
+                    MethodCallRef(
+                        explicitReceiver,
+                        left.name,
+                        args,
+                        detectedBlockArgument,
+                        isOptional,
+                        explicitTypeArgs
+                    )
+                } else if (left.methodId == null && left.fieldId != null) {
                     CallRef(left, args, detectedBlockArgument, isOptional, explicitTypeArgs).also { callRef ->
                         applyExplicitCallTypeArgs(callRef, explicitTypeArgs)
                     }