Smalltalk on Objective-C

Mon, 14 Jul 2008 10:47:10 +0100

This looks interesting:

This week, I committed the first version of the Smalltalk compiler I have been working on to �toil� svn. Unlike other Smalltalk implementations, this is designed from the ground up for interoperability. Smalltalk objects are compiled (to native code) as Objective-C objects. This means that they can subclass Objective-C objects, and can even implement categories on Objective-C objects. There is no C function interface - if you want to call C functions then call them from Objective-C.

The compiler is in three components. SmalltalkKit contains everything required to take a string containing Smalltalk code and compile it to a set of Objective-C objects.

The Support library contains things needed by Smalltalk but not Objective-C. The most important class here is the BlockClosure class, which implements a Smalltalk block as an Objective-C object with a function pointer as an instance variable and pointers to bound variables and space for promoting other variables (eliminating the need for garbage collected stack frames). There are also a few categories, such as map: and related methods on NSArray which take blocks as arguments. Note that these are implemented in Objective-C even though they are used by Smalltalk - they could, in most cases, easily be implemented in Smalltalk instead.

Compiled Smalltalk on top of Objective-C? Damn! I wish I had time to look more closely but I haven't even had time to pursue Nu. I note in passing that it's implemented using LLVM which is something else I wish I had time to explore.

Curiouser and Curiouser! on llvm

Smalltalk on Objective-C