class.eu

// module name shoild follow folders, like PSR-4
module controllers

import "http" exposing Request, Response

export class HelloController {
    
    exposed function handle(req Request, res Response) {
        return res.send("Hello")
    }
}

hello.eu

import "http" exposing HttpServer, Request, Response
import "controllers" as c

function main() {
    HttpServer.get("/", c.HelloController.handle)
    
    HttpServer.listen(8080)
}