I'm proud of my syntax definition language.

It means built-in commands can be sent as regular HyperTalk messages and parts of Stacksmith could possibly be implemented as regular HyperTalk. Also, later once I add a modern equivalent for XCMDs, one can define English-like syntax for the built-in XCMDs.

(Syntax definitions are only parsed once at startup, so stacks can't provide their own new syntax)