Module tp.client.pyscheme.analyzer

An analyzer that does syntactic analysis of an expression.

Danny Yoo (dyoo@hkn.eecs.berkeley.edu)

analyze() returns a function that can be evaluated just by calling it
with the environment and continuation.  It's based (or bastardized,
depending on your perspective... *grin*) on material in Chapter 4.1.7
of Structure and Interpretation of Computer Programs:

http://mitpress.mit.edu/sicp/full-text/book/book-Z-H-26.html#%25_sec_4.1.7

This is slightly more complicated since I'm using continuation passing
style and trampolining to get around Python's call stack.

The core forms that the analyzer recognizes is the following:

    self evaluating expressions
    variable references
    QUOTE
    SET!
    DEFINE
    IF
    LAMBDA
    BEGIN
    function application

Other special forms are handled by derivation: the expander module translates
the derived forms into these core forms.

FIXME: the analyzer itself is not in continuation passing mode.  The
analyzed expressions that it produces do use CPS.

FIXME: quasiquotation hasn't been pushed off into the expander yet.

analyze(exp) -> lambda env, cont: ...
Given an expression, returns a new lambda function that can be applied
on an environment and continuation.

Applies a procedure on a list of arguments.

This version of eval calls analyze, and then texec()s it
against the environment.

Executes each operand and constructs a new list.

texec applies the analyzedExpression against the environment.
Trampolined by eval(), and will be used by primitives like EVAL
and CALL/CC.