This was a pain point. I had hacked the "names" of symbols into the
throw/catch representation, never appreciating how badly I was screwing
up my understanding of LiSP. The symbols are supposed to evaluate
to something. When they're self-evaluating expressions (strings and
numbers), those become the keys in the block stack that matter. Getting
SEE's right, whether they're quoted or not, was really signficant.
This is cool. Now, on to rewind/protect!
This is a big refactoring; the parser is now modal, to handle either
complex Node objects that carry around a lot of state with them, or
simpler objects that represent the McCarthy-style IST. I'm still
feeling my way through the subject material. The node construction
is such pure artifice I feel silly keeping it, and may end up revising
it (again).
The nice thing is, everything goes through evaluate. Almost no other
code needs to know anything at all about the shape of the Nodes themselves;
it all makes assumptions based on the return value (or continuation passed)
by evaluate.
This also adds a number of accesory functions necessary for rationalizing
the record structure of an object in the lex/parse phase into something
more lisp-like. There's a metadata issue here that I'm not quite wrapping
my head around.
Elf M. Sternberg
Ken Elf Mathieu Sternberg