Question

What are examples of well designed functional (as opposed to object oriented) web apps that make their source code available? I am currently studying the Hacker News source but I’d like to see some other non-trivial examples, ideally in clojure.

For MVC there are lots of Rails and PHP apps, frameworks, and tutorials to study – what is there for functional programming?

Answer 1

There’s:

• Compojure (clojure)
• PLT Scheme Webserver (PLT Scheme)
• Erlyweb (erlang)
• Seaside (smalltalk)

That list is enough to keep you busy giving a sample of functional languages with different characteristics:

• Clojure: multi-paradigm?, flexible? it isn’t a pure functional language and although it is preferred that you program in a functional style, it isn’t strictly necessary. You can write java-style OOP through the Java interop, or you can abstract away from it using multi-methods. There’s a lot of flexibility there, although it is still a little early to say whether it is just “flexible” or “multiparadigm” in the way common lisp is. Designed, in part, to be a lisp that handles concurrency easily, it actually shoots at a lot of targets, hence the flexible or multiparadigm designation.
• Scheme: Closer to being a pure functional language than Clojure, it pushes the programmer a bit more forcefully into a functional style than does Clojure.
• Erlang: Functional programming built for reliable concurrency. Erlyweb is built on a platform that is designed to be highly concurrent.
• Smalltalk: Highly OO functional programming (even control structures are objects within the object system, and not syntactic constructs).

If you want to see how webapps look in a language that is functional “at all costs”, then the jrockway’s suggestion is the one to look at.