This fast-moving guide introduces web application development with Haskell and Yesod, a potent language/framework combination that supports high-performing applications that are modular, type-safe, and concise. Fully updated for Yesod 1.4, this second edition shows you how Yesod handles widgets, forms, persistence, and RESTful content. Author Michael Snoyman also introduces various Haskell tools to supplement your basic knowledge of the language. By the time you finish this book, you'll create a production-quality web application with Yesod's ready-to-use scaffolding. You'll also examine several real-world examples, including a blog, a wiki, a JSON web service, and a Sphinx search server. Build a simple application to learn Yesod's foundation datatype and Web Application Interface (WAI) Output HTML, CSS, and Javascript with Shakespearean template languages Get an indepth look at Yesod's core monads for producing cleaner, more modular code Probe Yesod's internal workings: learn the request handling process for a typical application Build forms on top of widgets by implementing the yesod-form declarative API Learn how Yesod and Haskell handle persistence and session data Serve an HTML page and a machine-friendly JSON page from the same URL