by mpweiher | 2025-11-05 20:09:10+00:00
>> most impressive part of Smalltalk ecosystem is the structure of the image

> The image concept, in my opinion, is what really limited Smalltalk's appeal and distribution.

I'd say these statements are both true. The image concept is very impressive and can be very useful, it certainly achieved a lot of bang for very little buck.

And it also was/is one of the major impediments for Smalltalk, at least after the mid 1980s.

The impressive bit is shown by pretty much the entire industry slowly and painfully recreating the Smalltalk image, just usually worse.

For example on macOS a lot of applications nowadays auto-save their state and will completely return to the state they were last in. So much that nowadays if you have a lot of TextEdit windows open and wish to make sure everything is safe, you kill the program, you don't quit it.

Also, all/most of the shared libraries and frameworks that come with the system are not loaded individually, instead they are combined into one huge image file that is mapped into your process. At some point they stopped shipping the individual framework and shared library binaries.

User interfaces have also trended in the direction of a an application that contains its own little world, rather than editing files that exist within the wider Unix filesystem.

The image accomplished all that and more and did so very efficiently. Both in execution speed and in amount of mechanism required: have a contiguous piece of memory. Write to disk, make a note of the start pointer. On load, map or read it into memory, fix up the pointers if you didn't manage to load at the same address and you're ready to go. On G4/G5 era Macs, the latter would take maybe a second or two, whereas Pages, for example, took forever to load if things weren't already cached, despite having much less total data to load.

But the drawbacks are also huge. You're really in your little world and going outside of it is painful. On an Alto in the mid to late 1970s I imagine that wasn't much of an issue, because there wasn't really much outside world to connect to, computer-wise, and where would you fit it on a 128KB machine (including the bitmap display)? But nowadays the disadvantages far outweigh the advantages.

With Objective-S, I am building on top of Cocoa's Bundle concept, so special directories that can contain executable code, data or both. Being directories, bundles can nest. You can treat a bundle as data that your program (possibly the IDE) can edit. But you can also plonk the same bundle in the Resources folder of an application to have it become part of that application. In fact, the IDE contains an operation to just turn the current bundle into an application, by copying a generic wrapper application form its own resources and then placing the current bundle into that freshly created/copide app.

Being directories, data resources in bundles can remain standard files, etc.

With Objective-S being either interpreted or compiled, a bundle with executable code can just contain the source code, which the interpreter will load and execute. Compiling the code inside a bundle to binaries is just an optimization step, the artifact is still a bundle. Removing source code of a bundle that has an executable binary is just an obfuscation/minimization step, the bundle is still the bundle.