I finally found time to get back to this. I found that it was easier to implement (i.e. many fewer changes to the existing Julia implementation) a more complex proposal where quote can be either hygienic or non-hygienic depending on whether it is used inside of a macro. However, it still seems like it should look very simple and straightforward to macro authors, which is my goal.
I have this working on my Linux machine. I can send diffs if anyone is interested. I don't know whether it is too late to make a change like this in the 0.3 release. Here's my strategy: Deprecate esc() and make it not do anything. Instead, quote marks all symbols that appear directly in the quote, rather than being interpolated, as hygienic. Post-processing of the macro expansion will replace these with the appropriate gensym, symbol, or module reference. Make a distinction between hygienic and non-hygienic quote, because quote is not only used by macros. Only hygienic quote does the above. Quote is hygienic when it is in the body of a macro or inside an @hygienic annotation. The output of hygienic quote will only work as part of a macro expansion, it will not work with eval. Unary : always behaves the same as quote. As a special exception, quoting a single symbol never makes it hygienic. This seems to be the best compromise to maximize usability without adding a new construct to reflect the fact that quoting a single symbol is sometimes used to construct executable code and other times used just to quote data. Fix the few macros in the base code that were broken by these changes. In the interest of simplicity, there are NO changes to the C code.
