[R6RS] Enumerations proposal pre-draft
William D Clinger
will at ccs.neu.edu
Thu May 18 15:05:55 EDT 2006
> > For <type-name>, how about we make it into a procedure of zero
> > arguments that returns the universe as a set?
> No. I meant "giving in" in the sense of "accept your proposal, with
> overloading", not doing something else.
Ouch. May I suggest a different compromise?
How about we flush the <index-of> procedure altogether?
Nothing in the proposal uses it, and it's hard to imagine
any good use for it. If there were a good use for it, it
could be defined in terms of any subset of the associated
(define (make-indexer set) ; untested
(let* ((symbols (enum-set->list (enum-set-universe set)))
(cardinality (length symbols)))
(let ((probe (memq x symbols)))
(- cardinality (length probe))
If we can agree to flush the <index-of> procedure, this
simplification would make it easier for us to agree on
changing the short form to require, or at least to allow,
either the <constructor-syntax> or <constructor>, which
would offer a way to construct a set from the short form
without the overloading of <type-name> that both of us
In summary, I am suggesting we:
1. flush <index-of> altogether
2. revert <type-name> to your original macro (although
your draft also referred to it as a procedure and
used it as such; my repair of that bug was what
led me to overload <type-name>).
3. either require or allow the short form to specify
either <constructor-syntax> or <constructor>.
Another issue that needs to be resolved is whether the
<constructor> takes a bunch of symbols as its arguments,
or a list of symbols as its single argument.
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