C programs in Scheme syntax

[Keith Wright]

I am thinkging about a project that uses Scheme macros
to generate C code.  To this end I want to encode C 
programs as S-expressions.  For example, the C program
that is encoded in Ascii as

for (j=0;j<12;++j) a[j] = j*pi/6;

might be encoded as an S-expression as

(for ((= j 0)(< j 12) (++ j)) (= (sub a j)(/ (* j pi) 6)))

Note that this is not a valid Scheme program, even with
non-standard functions defined.  It is a re-encoding
of the Ascii C syntax as an S-expression.

I think I have read about something like this, perhaps
on this list, I am not sure.  (Note to future language
inventors: a single letter name makes a horrible Google
search query.  Name things with made up but pronouncable
words---perl, fortran...)

I most need to convert S-expr encoded C, to Ascii encoded C,
but I am interested in
(a) programs to convert S-expresions to C
(b) specifications for the form of the S-expr encoding
(c) better plans; advice from those who have tried and failed.

Any pointers?

   -- Keith