I'm not a lisper either, but I think the key idea, and I've looked but can't find the reference for this, is expanding the language space to intersect the probl

I'm not a lisper either, but I think the key idea, and I've looked but can't find the reference for this, is expanding the language space to intersect the problem space. Any given language has a domain of problems it's suited to: manipulating number, strings, objects with loops and conditionals and organizing code with data (oop). This is the language domain. Then users (programmers) create abstractions with the language to represent a problem domain (payment processing, cms, reddit, whatever). The idea with macros is to extend the syntax of the language to move the entire language to the problem domain, for example the html generating dsl pg and company used at viaweb (see his writing). This distinction is not as profound today, imo, because languages have come a long way. Php didn't exist when pg and friends were doing viaweb, today templating html is old hat, but at the time specifying a dsl in lisp macros to dyanmcically generate html was quiet innovative.