Ceylon Express Typesafe Interface

run.ceylon

"Run the module `my.blog`."
shared void run() {
	
	Application app;
	
	app = Application();

	dynamic server = app.js.listen(3000, void () {
		dynamic {
			console.log(
				"Express is listening to http://localhost:3000"
			);
		}
	});
	
}

shared dynamic AppInterface {
	shared formal void listen(Integer port, Anything() callback);
}

shared class Application() {
	
	"Encapsulates express logic that works when not interfaced"
	dynamic dynRequire() {
		dynamic {
	 		dynamic required = require("express");
	 		//must call here; otherwise gets "type not callable" errors
	 		dynamic calledRequired = required();
	 		return calledRequired;
	 	}
	}
	
	"Should apply interface to javascript code"
	AppInterface dynInit() { 
		dynamic {
			return dynRequire(); 
		}
	}
	
	"Contains the actual js object."
	shared AppInterface js = dynInit();
}

I think this is actually quite different from the new JavaScript pattern as this is calling a constructor function in js and ceylon-js code just keeps giving undefined errors.

What exactly does require("express") return? Is it really a function? Do you need to invoke that function with new or just a normal invocation?

just a normal invocation but I've run into two problems getting it to invoke:

1. If I apply an interface to its return, i try to call it and i get a "not callable" error. (Maybe you could add dynamic() Application { ... } where the parens indicate a callable dynamic interface)
2. If I try to call it as shown (within a dynamic block) I get this error:

if(type.t.$$.T$name in obj.getT$all()){
                           ^
TypeError: Cannot use 'in' operator to search for 'my.blog::AppInterface' in undefined
    at is$ (C:\Users\madca_000\.eclipse\org.eclipse.platform_4.4.1_1167611518_win32_win32_x86_64\plugins\com.redhat.ceylon.dist.repo_1.1.1.v20150208-2150\repo\ceylon\language\1.1.1\ceylon.language-1.1.1.js:340:28)
    at Object.dre$$ (C:\Users\madca_000\.eclipse\org.eclipse.platform_4.4.1_1167611518_win32_win32_x86_64\plugins\com.redhat.ceylon.dist.repo_1.1.1.v20150208-2150\repo\ceylon\language\1.1.1\ceylon.language-1.1.1.js:698:5)
    at $init$Application.application$.$5 (C:\Users\madca_000\eclipse\ceylon-express-attempt\modules\my\blog\1.0.0\my.blog-1.0.0.js:93:28)
    at Application (C:\Users\madca_000\eclipse\ceylon-express-attempt\modules\my\blog\1.0.0\my.blog-1.0.0.js:65:35)
    at run (C:\Users\madca_000\eclipse\ceylon-express-attempt\modules\my\blog\1.0.0\my.blog-1.0.0.js:14:8)
    at [eval]:1:283
    at Object.<anonymous> ([eval]-wrapper:6:22)
    at Module._compile (module.js:456:26)
    at evalScript (node.js:536:25)
    at startup (node.js:80:7)

Here is the express.js code from the main export file:

exports = module.exports = createApplication;

/**
 * Create an express application.
 *
 * @return {Function}
 * @api public
 */

function createApplication() {
  var app = function(req, res, next) {
    app.handle(req, res, next);
  };

  mixin(app, proto);
  mixin(app, EventEmitter.prototype);

  app.request = { __proto__: req, app: app };
  app.response = { __proto__: res, app: app };
  app.init();
  return app;
}

It's the same way that koa.js handles it too.

OK there were a couple of issues with some of the core functions when dealing with a native function with additional stuff; I've just fixed that. And now I've just started a little express server with this:

dynamic Response {
  shared formal void send(String text);
}

dynamic ExpressApp {
  shared formal void listen(Integer port, Anything() callback=()=>null);
  shared formal void get(String url, Anything(Anything,Response) callback);
}

shared void run() {
  ExpressApp app;
  dynamic {
    app=require("express")();
  }
  print(app);
  app.get("/", (req,resp) {
    print("Responding...");
    return resp.send("YEAH!");
  });
  app.listen(3000,
    ()=>print("OK, listening on port 3000"));
}

Excellent! I'll pull ceylon-js later this afternoon then and give it a go!

Don't forget to pull ceylon.language as well, since the latest fixes were in native JS code.