On Tue, Aug 25, 2009 at 3:14 AM, Peter Bex<[email protected]> wrote:
>
> Not necessarily.  I think all low-level systems allow for breaking of
> hygiene, but that's not the reason to prefer a low-level system.
> A low-level system is useful because it allows one to explain macros
> in terms of familiar Scheme primitives as cons, car and cdr.
> This simplicity fits well with Scheme, and I think it would also serve
> well in an educational setting - having to explain that high-level
> macro systems are their own language separate from Scheme is yet another
> layer of complexity.

The macro system usually referred to as 'syntax-case' doesn't rely on
the syntax-case macro.  In particular, only one additional primitive
function and one simple primitive form [1] not provided in the R6RS
are needed to implement the `syntax-case' as a library.

[1] PLT Scheme names these forms `syntax-local-value' and `quote-syntax'.

-- 
sam th
[email protected]

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