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questions about `condition-property-accessor'

This page is part of the web mail archives of SRFI 12 from before July 7th, 2015. The new archives for SRFI 12 contain all messages, not just those from before July 7th, 2015.

A great SRFI.  My thanks to the authors.

I do have some questions about the functions returned by

Question 1: What predicate is used to compare prop-keys?

The implementation uses `eq?' (via `assq' and `memq') for both
kind-keys and prop-keys.  The specification says that kind-keys
are compared using `eqv?' and says nothing about how prop-keys
are compared.

The rest of the questions relate to the following condition:

  (define condition
    (make-composite-condition (make-property-condition #f 0 'a 1 'b)
                              (make-property-condition #f 0 'c 1 'd 2 'e)))

Question 2: What happens if I ask for a property that the condition
doesn't have?

  ((condition-property-accessor #f 3) condition)  -->  ???

Question 3: What if I ask for a property that only one of the two
subconditions has?

  ((condition-property-accessor #f 2) condition)  -->  ???

Question 4: Will the accessor always use the same subcondition?
Can the following return (a d) or (c b), or must it return (a b)
or (c d)?

  (list ((condition-property-accessor #f 0) condition)
        ((condition-property-accessor #f 1) condition))
    --> ???