Re: [xacml] straw poll on "<type>-map" or "map"

[Polar Humenn <polar@syr.edu>]

My vote is for "map".

Rationale:

The primitive functions, i.e. integer-equal, are named with their
arguments' particular type, not their resultant type. If you named
functions for their resultant type, as is suggested with "integer-map"
returning a bag of integers regardless of what its argument type is, then
to be consistent with that naming convention would mean the "equals"
function between integers would be called really be called "boolean-equal"
because equal returns a boolean. And that would lead to inconsistent, not
to mention, nonsensical naming.

The functionality of "map" is independent of the primitive type of the its
arguments, where as "integer-equal"  is not, "integer-equals" requires two
integers as arguments. The function "map" only requires the supplied
function and the supplied bag to agree on types, no matter what the type
happens to be. It is truly polymorphic.

I think naming "integer-map" is really confusing as it only states half
the type story, the rest is left in the air. If you were to fully specify
the type in the name, you'd have to say something like "integer-float-map"
for functions that map bags of integers to floats (or visa versa depending
on how you want it". That would cause an explosion of type names, which is
unnecessary, because the <Function> argument really specifies the type.

Also, for extension types, the function "map" can easily and with formal
integrity, be used for any extension type and any other extension
functions that do conversions or selections of that type.

Furthermore, this "map" function didn't come out of nowhere, it is the
most popular polymorphic function on the planet. :)

Cheers,
-Polar

On Mon, 25 Nov 2002, Anne Anderson wrote:

> The list discussion is not coming to any resolution on Comment#
> 0033. http://lists.oasis-open.org/archives/xacml-comment/200211/msg00061.html
> Subject: map function
> From: Seth Proctor <seth.proctor@sun.com>
> Date: Wed, 20 Nov 2002 16:22:32 -0500
>
> Since it looks like a vote may be required, but a vote will not
> be possible until December 5, I would like to take a straw poll
> to see how the vote is likely to go.  This will allow intrepid
> implementors to implement "the most likely" outcome now (at some
> risk of having to change after Dec. 5).
>
> This is not an official e-mail vote, and is non-binding: on
> December 5, we can vote "officially" and your vote can differ
> from the one you submit to this straw poll.  But if you think you
> know how you would vote and are willing to post that now, please
> do.
>
> My straw poll vote is: <type>-map
>
> Rationale:
> 1) Consistent with type system implied by every other XACML
>    function.
> 2) If we polymorphic output "map", then we should use polymorphic
>    functions everywhere (i.e. "equal", not "string-equal"
>    "integer-equal" "boolean-equal", etc.)
> 3) Makes type checking easier for the user and for the
>    implementation.
>
> Anne Anderson
> --
> Anne H. Anderson             Email: Anne.Anderson@Sun.COM
> Sun Microsystems Laboratories
> 1 Network Drive,UBUR02-311     Tel: 781/442-0928
> Burlington, MA 01803-0902 USA  Fax: 781/442-1692
>
>
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