Overriding widgetFile - yesodweb/yesod GitHub Wiki

You can modify the behavior of widgetFile in the scaffolding by changing the widgetFileSettings value in Settings.hs. As an example:

widgetFileSettings = def { wfsLanguages = \hset -> defaultTemplateLanguages hset ++
    [ TemplateLanguage True  "coffee"  Text.Coffee.coffeeFile   Text.Coffee.coffeeFileReload
    ] }