Question

I’m having a bit of trouble trying to understand how WARP could potentially interact with the client-side. If I were to build my server-side via WARP, and had a Javascript client-side. Could I hypothetically use AJAX as the bridge between the client side and server-side?

Answer 1

Yes. AJAX doesn’t need to know anything about your server to work. All it needs to do is request something at a url, and get a response.

For example, suppose you are using jquery. Your Ajax request could look like:

$.ajax({
  url: "/hello",
}).done(function() { 
  $(this).addClass("done");
});

This is requesting something at url /hello. Then your Yesod app needs to serve something at /hello:

mkYesod "yourapp" [parseRoutes|
/hello HelloR GET
|]

getHomeR :: Handler RepHtml
getHelloR = defaultLayout [whamlet|Hello!|]

(I haven’t used Yesod, so I can’t claim that that code is accurate).

Since WARP is a WAI handler, you can run any WAI application on it. Here’s another example, this time using scotty:

main = scotty 3000 $ do
  get "/hello" $ html "Hello!"