Re: [Scheme-reports] 6.4 control features: -map and -for-each procedures
John Cowan 21 May 2011 21:09 UTC
Andy Wingo scripsit:
> Right, control features. I already mentioned the
> multiple-return-from-mapping proc issue before. There are three
> options that I am aware of:
>
> 1) Ignore the issue.
>
> 2) Specify that a second return from a mapped procedure cannot
> affect the data structure returned by the first return. Effectively
> prohibits the build-it-backwards-and-reverse-in-place idiom, though
> you may reverse and form a new list.
>
> 3) Specify that it is an error to return multiple times.
I have filed a ticke for choice 3. I don't see that anyone will want 2,
especially for string-map and vector-map.
> Suggestion: that it be an error for a mapped procedure to mutate the
> list being mapped.
Ticket filed.
> Also, what is the motivation for having multi-arg `map' terminate at
> the first empty list?
Compatibility with the widely accepted SRFI 1.
> 5) You'd need blob-map to be complete, for this report...
Ticket filed to complete blob.
> Suggestion: remove vector-map, string-map, and their for-each
> procedures from the WG1 report.
The WG1 charter says: "Self consistency is an important objective,
which may require adding new features."
--
John Cowan <cowan@ccil.org> http://www.ccil.org/~cowan
Raffiniert ist der Herrgott, aber boshaft ist er nicht.
--Albert Einstein
_______________________________________________
Scheme-reports mailing list
Scheme-reports@scheme-reports.org
http://lists.scheme-reports.org/cgi-bin/mailman/listinfo/scheme-reports