Architectural Overview

Here is a very brief architectural overview.

The architecture of Vista Smalltalk is best described as having three layers:

1. User Language
2. Lisp
3. Primitive Base

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User Language Layer
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The term “User Language” indicates any language which is designed for end-user interaction, such as:

•  Smalltalk
•  Basic
•  Python
•  Other

There are currently grammars for Smalltalk and Basic - the “Other” category might include specialized languages for modelling or games. “User” languages are converted to and from Lisp s-expression format for internal use.

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Lisp Layer
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The Lisp used internally is a very small dialect designed specifically for building object-oriented applications. It is implemented as an interpreter written in ActionScript (for Flash) or C# (for .Net). When C# 3.0 is released, I plan to add a compiler to the .Net version.

 It features:

• reader macros
• macro expansions
• standard list functions
• closures
• Xlisp-style messaging
• Smalltalk-like objects

Advantages of using Lisp are:

• macros
• excellent serialization
• mix data/code
• basis for AI techniques

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Primitive Base
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The primitive base is written in the host language of the implementation - C# for .Net or ActionScript for Flash.

It has three components:

• interpreter
• object system
• Lisp primitive functions

Language capabilities can be extended by adding new Lisp primitive functions which are then accessible by user languages such as Smalltalk.

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Summary
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The architecture has these goals:

• replace Javascript with better languages
• replace MXML/XAML with Lisp
• portable accross Flash or .Net
• extensible architecture
• basis for next generation AI