管道 Debug.log

在运行时，以下内容将在控制台中显示 url 列表并继续计算

payload =
    [{url:..., title:...}, {url=..., title=...}]

main = 
    payload
        |> List.map .url -- only takes the url
        |> Debug.log " My list of URLs" -- pass the url list to Debug.log and return it
        |> doSomething -- do something with the url list