Edit: Fixed some factual inaccuracies about the language itself.
Tim Burks, noted contributor to RubyCocoa and creator of RubyObjC, gave a talk at C4[1] about his experiences with creating a Ruby <-> ObjectiveC bridge, and the problems he overcame in doing so. It was an interesting presentation, and we were all suitably appreciative when he showed his custom visual chip-design software written in Ruby with a Cocoa interface.
And then he dropped a bombshell.
For the past year, Tim’s been working on a new dialect of Lisp – written in Objective-C – called Nu. Here are its features (more precisely, here are the ones that I remember; I was so awestruck that many went over my head):
- Interpreted, running on top of Objective-C.
- Scheme-y syntax. Everything is an s-expression (data is code, code is data). Variable assignment was done without let-clauses (which are a pain in the ass) – all one has to do was
(set varname value). - Variable sigils to indicate variable scope.
- True object-orientation – everything is an object.
- True closures with the do-statement – which, incidentally, is how Ruby should have done it.
- Macros. HOLY CRAP, MACROS! When Tim showed us an example of using
define-macrofor syntactical abstraction, Wolf Rentzsch and I started spontaneously applauding. His example even contained an example of absolutely beautiful exception handling that should be familiar to anyone with any ObjC or Ruby experience. - Symbol generation (__) to make macros hygenic and prevent variable name conflicts.
- Nu data objects are Cocoa classes – the strings are NSStrings, the arrays NSArrays, etc.
- Ability to create new Obj-C classes from inside Nu.
- Interfaces with Cocoa libraries – you can access Core Data stores from within Nu in a much easier fashion than pure ObjC, thanks to Tim’s very clever idea of using a $session global to store the NSManagedObjectModel, NSManagedObjectContext, and NSPersistentStoreCoordinator.
- Ruby-style string interpolation with #{}.
- Regular expressions.
- Positively drool-inducing metaprogramming, including a simulation of Ruby’s
method_missingfunctionality. - A web-based templating system similar to ERb in 80 lines of Nu code – compare that with the 422 lines of code in erb.rb.
Tim showed us a MarsEdit-like blog editor written entirely in Nu, using Core Data as its backend – and then showed us the built-in Nu web server inside that program, complete with beautiful CSS/HTML/Ajax.
As F-Script is to Smalltalk, so Nu is to Lisp. Tim said that he hopes someday to open-source Nu; if he does, he will introduce what is quite possibly the most exciting development in the Lisp-related community in a long time. I don’t think I speak for just myself when I say I cannot wait to get my hands on it.