There are times when we want to just write some Elm code and see what happens without having to install the Elm Platform and other required tools. The Try Elm site is perfect for that. Let’s run the Elm code for our home page on this site. Copy everything in the HomePage.elm file except the first line: module Main exposing (..) and paste it on the left hand side. After that click the Compile button. You should see our home page again on the right side.
The reason we can’t include the line that defines a module is because the Try Elm site creates a module of its own behind the scenes. And Elm doesn’t allow us to have two module definitions in one file. We will cover modules in detail in chapter 4.