programming musings

I am very fond of Mac OS X’s graphical interface. As a GNU/Linux or FreeBSD user, i despise GUIs and usually work in a mostly text-based ambient powered by Emacs running inside a urxvt terminal. Things change dramatically when i enter OS X. There i discovered that it is not that i dislike GUIs, but that i dislike ugly GUIs (although the jury is still out on where i’m more productive).

Thus, OS X is the only environment where i feel like programming a GUI. From a programmer’s viewpoint things also start out better: one can go native and avoid C and C++. Cocoa’s native language is Objective-C, which happens to be a dynamic language. That is, one has a runtime where possibly dynamic objects live, good (but not great) reflective capabilities and a meta layer that let’s you, for instance, access class and metaclass objects. And all that at runtime. That allows (besides the fun of programming) funny tricks, like the ability to interact with running applications from the outside, in what constitutes an incredibly flexible plug-in system.

Probably the description above rang a bell: Smalltalk. Objective-C is a scaled down Smalltalk in many ways. The good news is that you can have the real thing: F-script is a Smalltalk dialect specifically designed to script Cocoa applications. It let’s you inspect any running Cocoa application, and manipulate the objects it contains in real time, so to speak. As any decent Smalltalk, it comes with a powerful object browser, which you can admire in all its beauty below. Moreover, F-script can be embedded in your Cocoa application, acting as an excellent extension language, way more cool than Apple’s default scripting language. A beautiful application taking full advantage of these abilities is ObjectiveCLIPS, a powerful rule-based development environment for Cocoa.

But still, to my knowledge, you cannot program a whole application in F-Script and, besides, Smalltalk is all very well, but it’s not Lisp. Support for Lisp in the Cocoa world is not as good, but shows promise. First, there’s OpenMCL, an excellent Common Lisp implementation for the Mac and Unix systems that comes with a Cocoa bridge. It includes a demo Cocoa IDE to get you started, and people have gone as far as creating games using it.

Until recently, poor Schemers were left in the cold. Enter Chicken and its Objective-C egg. Support is still rudimentary, but there’s already a nice tutorial on writing a currency converter, the default Cocoa Hello World app.

Probably, it’s still too hard to write a well-integrated Cocoa application using Lisp, but i think it’s just a matter of time. Happy hacking!

Tags: lisp, osx, objective-c, scheme, smalltalk