hello_controller.ex

defmodule Hello.HelloController do
  use Hello.Web, :controller
  plug :action

  def world(conn, %{"name" => name}) do
    render conn, "world.html", name: name
  end
end

hello_view.ex

defmodule Hello.HelloView do
  use Hello.Web, :view
end

router.ex

defmodule Hello.Router do
  use Hello.Web, :router

  pipeline :browser do
    plug :accepts, ["html"]
    plug :fetch_session
    plug :fetch_flash
    plug :protect_from_forgery
    plug :put_secure_browser_headers
  end

  pipeline :api do
    plug :accepts, ["json"]
  end

  scope "/", Hello do
    pipe_through :browser # Use the default browser stack

    get "/hello/:name", HelloController, :world
    get "/", PageController, :index
  end

  # Other scopes may use custom stacks.
  # scope "/api", Hello do
  #   pipe_through :api
  # end
end

world.html.eex

<h1>From layout: Hello <%= String.capitalize @name %>!</h1>