Scala, Clojure and Lisplets
December 22, 2007
The good thing is that through the comments of this post I learned about a few things, either directly or indirectly. Some of these thing have been around for a long time, but hey, I’m just learning about them.
First, there is a ground swell of support for Scala. I checked out the docs on their site and does look like a very powerful, expressive language. It seems to have many of the features of Lisp without being a Lisp dialect. It is syntactically Java-ish, but unlike Groovy, which really for some reason just seems like much-needed syntactic sugar for Java, Scala feels lieke a completely different language. In other words, and not that this is saying Groovy is a bad thing, but Groovy really isn’t conceptually different than Java, where as Scala is, with things like case classes, for example. This is a language I’ll have to look into some more.
There is also a mention of a new List-dialect for the JVM called Clojure. Clojure creator Rich Hickey (you need a blog Rich) recently gave a presentation on Clojure at LispNYC and the audio and slides are there. Clojure has a bunch of interesting ideas in it which he explains in the presentation. Clojure has a literal syntax for vectors (a.k.a arrays, lists) and maps (a.k.a Hashtables, Dicts) in addition to the traditional lisp lists. It is not quite a purely functional language, but strongly encourages it, making it the default programming paradigm over object-orientation. I’ve been wanting to check out Haskell and Erlang to get familiar with the functional programming paradigm, but Clojure might be a good way to get some exposure to that as well.
Another thing I found is Lisplets, which was created by Rich Hickey as well a few years ago. It is a Java Servlet that packages up the entire environment of an HTTP request, request parameters, cookies, session, etc, into an S-expression that is then handed off to a Lisp interpreter that listens on a socket. Lisp then reads the s-expression, does whatever it does, and then returns data to the Servlet which gets sent to the client. Mod_lisp is based on a similar concept. I think it’s kind of interesting to think of web development in this manner, with a definitive layer of abstraction between the processing of request into a data structure, and then processing the request based on that data structure.