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Re: Specification



On 6/26/06, Andre van Tonder <andre@xxxxxxxxxxxxxxxxx> wrote:

I like the operational semantics in the SRFI, since it may be less ambiguous
than the alternative declarative approach.

As corrobrating evidence, I can mention the syntax-case implementation in
SRFI-72.  That implementation satisfies declarative descriptions of
hygiene.  However, the implementation technique is based on an "implicitized"
version of explicit renaming, not marking/substitution.  There are some highly
obscure corner cases where it behaves differently from the marking algorithm,
while still satisfying hygiene.  I have to recheck, but I think these
ambiguities should be resolved by specifying the algorithm as is
done here (though perhaps a little more detail might be required).

I think the trick is to make an unambiguous declarative specification.

David