zhtw, your profile says you're building a lisp compiler, so I'm taking the liberty of exposing the innards of rainbow a little, it might be helpful:
public class Symbol {
String name;
ArcObject value;
// ... etc
}
Pieces of arc code contain direct references to these Symbol objects. For example, (car x) is implemented by something like this:
class Invoke_Sym_Lex {
Symbol fn; // points to the "car" symbol
LexicalSymbol arg;
public void invoke(...) {
fn.value.invoke(arg);
}
}
there is no lookup. The symbol is baked into the code. Lexically-bound symbols are more complicated, but they don't use hashes for lookup either.
As far as I can tell, this approach will support namespaces without any performance penalty, except perhaps at read/compile-time. Assuming arc gets namespaces one day ...
