sexp

Is this a sane representation for s-expressions?

struct O
{
union {
Cell *o;
char *a;
};
int type;
};

struct Cell
{
O car, cdr;
};

Why LISP compiler are written in C/C++?
1. Implement LISP compiler N in LISP and C.
2. Compile N using #1 lisp compiler resulting in N2 compiler.
3. Compile N in N2 resulting in N3.
4. Compile N in N3 resulting in N4.
5.Repeat until the program binary output is identical to previous iteration.
6.Compile N in C, and benchmark #5 versus it.
7.Report results.