A Lisp interpreter, not working yet, in Python. This is a quick
and dirty work, built in four days. I regret having chosen this
as my course assignment, since the course is targeted at non-CS
students like I am. This is way too hard for me.
It's likely to improve in the future, but will be *very* slow.
Just think of it as a toy.
The dialect is more like scheme, uses lexical scoping and full
closures. Functions are first-class. Design of macro is, by
now, very dirty --- dynamically scoped & first class macros. No
first-class continuations yet.
I wonder if it's Turing-complete now, but nothing really works,
except those well-known axioms. No string & numerical features