Ceylon Express attempt

express.ceylon

dynamic Express {}

Application requireExpressAndCallConstructor() {
	dynamic { return require("express")(); }
}

dynamic Request {}

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

dynamic Application {
	
	shared formal void get(String path, 
		Anything(Request, Response)|Null|Anything(Request, Response)[] callbacks=null);
	
	shared formal Server listen(Integer integer, Anything() callable);

}

nodejs.ceylon

dynamic Path {
	
}

dynamic Server {
	
	shared formal dynamic address();
	
}

run.ceylon

"Run the module `my.express`."
shared void run() {
    
	Application app = requireExpressAndCallConstructor();
    
    	app.get("/", (Request req, Response res) {
        	return res.send("Hello world!");
	});
	
	Server server = app.listen(3000, () {
		
		//dynamic host = server.address().address;
		//dynamic port = server.address().port;
		
		dynamic {
			console.log(
				"Example app listening..."// at http://%s:%s",
				//host,
				//port
			);
		}
		return nothing;
	});
}

On Line 47 of express.ceylon, there are two functions with the same name, how do I do that in a dynamic ceylon interface like this?

Also on Line 14, I get an error that says that server is undefined. But this is how the javascript looks. I tried putting the two values inside of the dynamic block but I still get the error.

---

Now the big question I have is why can't I get this to run. 😄

I click "run as javascript application" on the run() function and I get this error:

ceylon.language::Exception "Undefined or null reference: express"

I have a node_modules folder in my main project directory with express in it. Is there some configuration that I am missing. I am really new to Eclipse. Should I be setting up a run configuration or something?

Also on Line 24 of run.ceylon there is the return nothing; expression and that was the only way I could get the typechecker to not fail. Is this proper Ceylon? Did I declare my dynamic type interface wrong? Is this just because I am trying to abstract away the dynamic calls and now i have to do that to make the callback work for the typechecker? I am stumped! 😖

There aren't two functions with the same name; it's the same function but it works differently depending on what arguments you pass it. To define those methods in a dynamic interface you can use union types and optional/defaulted parameters.

return nothing will throw at runtime, but I'm not sure what you need to return there.

Try adding your node_modules directory as a repository in the run-js command; that will add the directory to the NODE_PATH so that your express module is found at runtime.

Is this the right type for that get function?

shared formal void get(String path, 
        Anything(Request, Response)|Null|Anything(Request, Response)[] callbacks=null);

I added node_modules and am still getting the same error. However, I am not sure what you mean by run-js command. I'm using the IDE and the only place I can find to add repos is in the project properties menu under Ceylon Configuration > Module Repositories. Should I be added it to the Environment tab in Run Configurations?

I think the problem is with return express(), not with require('express'). node.js throws when it can't find a module, and the message is Cannot find module 'blah'; your message is different. There's no express function defined anywhere in your code. If the express module contains it, you'd need to call it as requireExpress().express().

I also see a createApplication defined inside the Express dynamic interface. I haven't used express so I don't know if createApplication is really a function inside that module, but I see you define your own toplevel method with the same name.

Yeah I was trying to get around the fact that in JavaScript you call the express constructor with 'express()' and I couldn't figure out how to get that to work in Ceylon because it seems like the compiler is looking for some function that I'm referencing there. I'm away from my computer but will requireExpress.express() run Express' constructor?

The createApplication function was what I thought Express was calling when it constructed but Express gave me an error when I tried to call it so I was just using the name to encapsulate the dynamic return of the constructor and also as a place to add the Application type to what the constructor returns.

I've updated the code per your suggestions @chochos and I am now getting a new error that I don't understand 😕

if(type.t.$$.T$name in obj.getT$all()){
                           ^
TypeError: Cannot use 'in' operator to search for 'my.express::Application' in undefined
    at is$ (C:\Users\madca_000\.eclipse\org.eclipse.platform_4.4.1_1167611518_win32_win32_x86_64\plugins\com.redhat.ceylon.dist.repo_1.1.0.v20141013-1416\repo\ceylon\language\1.1.0\ceylon.language-1.1.0.js:188:28)
    at Object.dre$$ (C:\Users\madca_000\.eclipse\org.eclipse.platform_4.4.1_1167611518_win32_win32_x86_64\plugins\com.redhat.ceylon.dist.repo_1.1.0.v20141013-1416\repo\ceylon\language\1.1.0\ceylon.language-1.1.0.js:634:5)
    at requireExpressAndCallConstructor (C:\Users\madca_000\eclipse\ceylon-express-raw\modules\my\express\1.0.0\my.express-1.0.0.js:76:17)
    at run (C:\Users\madca_000\eclipse\ceylon-express-raw\modules\my\express\1.0.0\my.express-1.0.0.js:13:13)
    at [eval]:1:292
    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)
    at node.js:906:3

I know it has to do with calling the return of require (i.e., require("express")(); ) but that is how the JavaScript is done. Here is the example given in the Express.js docs:

var express = require('express')
var app = express()

app.get('/', function (req, res) {
  ...
})

var server = app.listen(3000, function () {

  ...

})

And when I don't call the return (i.e., require("express"); ), I get this:

    $3i.$_get("/",m$3h.$JsCallable((function($3j,$3k){
        ^
TypeError: Object 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;
} has no method '$_get'
    at run (C:\Users\madca_000\eclipse\ceylon-express-raw\modules\my\express\1.0.0\my.express-1.0.0.js:14:9)
    at [eval]:1:292
    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)
    at node.js:906:3