I wrote:
> It turns out that pure 'syntax-rules' macros are turing complete, but
> they are limited in the ways that they can inspect the syntax objects
> given to them as operands. In particular, they cannot inspect atomic
> expressions, except to compare them with the finite set of literals in
> the first operand to 'syntax-rules'. This is not sufficient to
> interpret an arbitrary integer literal. It could only be done with
> 'syntax-rules' macros if the 'count' field were represented using a
> finite set of literals and/or list structure. E.g. it could be done if
> the count were represented as a list of decimal digits like (1 4 2) for
> 142.
Correction: the finite set of literals that can be recognized by
'syntax-rules' macros must be identifiers, so a representation with bare
decimal digits like (1 4 2) would not work. Something like (_1 _4 _2)
would be possible, though.
Mark
