>>> However, generating the most optimal code may prove to be complicated.
>>> For instance, you’d want:
>>> (set-fields p (person-address address-city) "Düsseldorf"
>>> (person-address address-street) "Bar")
>>> to expand to:
>>> (set-person-address p
>>> (let ((a (person-address p)))
>>> (set-fields a (address-city) "Düsseldorf"
>>> (address-street) "Bar")))
>>> But that would require knowledge of the relationship between
>>> ‘address-city’, ‘address-street’, and the underlying record type, etc.
>> I don't understand why such knowledge is needed, or why this is
>> difficult. We have procedural macros. Simply sort the field-name-paths
>> lexicographically, split the sorted paths into groups with the same car,
>> and recurse. Am I missing something?
> Yes: nothing forces you to prefix names with ‘address-’ here.
I might be wrong, but I don't think you need any knowledge of the
names to make this work. In your example, the two field-name-paths are
(person-address address-city) and (person-address address-street).
They both have the car 'person-address, so you can pull that out to
generate your expansion:
(let ((a (person-address p)))
(set-fields a (address-city) "Düsseldorf"
I think it could be implemented without any knowledge of the names at
all. The lexicographical ordering is just a way to improve the
performance of finding common prefixes. A hash table would also work.