[r6rs-discuss] Records simplification/question

From: AndrevanTonder <andre>
Date: Mon Nov 6 14:36:29 2006

A couple of questions on records:

- I was wondering why there seems to be more indirection than would appear
   necessary in the procedural interface. In particular, why are
   constructor-descriptors necessary. Couldn't one have had just directly

    (record-constructor rtd parent-protocol protocol)

   without the need for constructor-descriptors?

- On p.67, it is not quite explained what happens if
   "parent-constructor-descriptor" is #f. The document states:

   "If rtd is an extension of another record type
    parent-rtd, parent-constructor-descriptor must be
    a constructor descriptor of parent-rtd or #f. If
    parent-constructor-descriptor is #f, a default constructor
    descriptor is supplied. In this case, p is a procedure that
    accepts the same number of arguments as the constructor
    of parent-constructor-descriptor ....."

   but the last phrase "the constructor of parent-constructor-descriptor"
   has no meaning here, if "in this case" refers to the case where
   "parent-contructor-descriptor" is #f, which the sentence seems to imply.
   I don't think that this was the intent, but this is the way it reads.
   In any case, I can't quite figure out from the prose what the default
   parent constructor descriptor is supposed to be in the #f case.

Andre
Received on Mon Nov 06 2006 - 14:32:43 UTC