Great post Mikael! So happy to read your thoughts.
On Sat, Jan 5, 2013 at 6:37 PM, Mikael mikael.rcv@gmail.com wrote:
The syntactic-closures based macro systems (syntax-rules/syntax case including define-syntax, syntax-rules, let-syntax, letrec-syntax) bring incredible complexity and with that low debuggability through a very complex identifier concept based a kind of duality of the identifier symbol in itself and the syntactic environment in which it is used in a particular instance, and brings a complex API for handling macros with this, that by nature is not Schemy and not suited for debugging.
Per came with the suggestions above based on having spent approx 6 months fulltime on developing the Black Hole module system, which does hybrid define-macro and syntactic closures expansion.
There might be some caveat I didn't get, but, I'd guess you could actually make a macro expander that supports both an alias macro system as per above and a syntactic-closures for compatibility with code that uses it, possibly by splitting expansion into two expansion phases, thus isolating all the identifier-related complexity.
While talking about the syntactic-closures, If we ignore syntax-case, I'll disagree that it brings "incredible" complexity. I've been uncertain on syntactic-closures for years, while this Holiday I finally got spare time reading its implementation in riaxpander/chibi-scheme, I found the concept of it is quite straight forward. Though I deadly missed an easy-to-understand, concrete implementation with document for it during the learning process.
I've cloned such a system in gambit, and keep digging on how to integrate hygiene with module system and gambit's compiling process.
Thanks Meng