[SOLVED] Customizing response headers in Wai middleware

Customizing response headers in Wai middleware

I'm currently using wai-middleware-static to serve up custom pages for my server. However, i saw that my server was getting requests for favicon.ico, etc. on every page load, and also every single one of my web fonts, so i decided to check the cache settings on the response headers and found that there were none.

wai-middleware-static returns a Middleware value, which I think is a callback to a function provided by the middleware that is run on every request. Is there a way to modify this to add in a response header to tell the browser to cache the result?

Solution

Multiple middlewares can be chained together with normal function composition, e.g.:

middleware1 . middleware2

So if you had a middleware that added the cache settings to the response, you should be set. A basic structure that may help you is:

addCacheSettings :: Middleware
addCacheSettings innerApp request = do
    innerResponse <- innerApp request
    return $ myHelper innerResponse
  where
    myHelper :: Response -> Response
    myHelper = error "Your logic here"