Seven Web Frameworks in Seven Weeks

Day 2: Views, Forms, and Auth

Web frameworks rely heavily on HTML templating systems to make adding dynamic output convenient. Unfortunately, most templating systems are thin veneers on string substitution, and as a result, it is very easy to introduce bugs and security vulnerabilities into your web app. For example, you might include incorrect links in a view or allow untrusted user-generated content to control a user’s browser.

Yesod includes several templating systems, but while they appear similar to ones you’ve no doubt seen before, they work very hard to prevent the kinds of bugs that are common in those other systems. In Yesod, URLs and inserted document content are type-safe, which means you don’t have to worry about updating views ...