[r6rs-discuss] library versions (was: Rationale issues)

[Mikael Tillenius]

William D Clinger escribió:
> I don't think it is useless to note that it is impossible
> for a programmer to write a library reference that cannot
> identify more than one library.  From that it follows that
> a programmer cannot avoid reliance on some implementation-
> dependent mechanism for mapping library names/versions to
> concrete libraries.  From that it follows that there is no
> such thing as a truly portable R6RS program that uses any
> libraries beyond those described in the two potentially
> normative reports.

Isn't this a bit to theoretical? As I see it a portable program can 
consist of a top level program and zero or more libraries. The source 
code for both the top level program and any libraries must be presented 
to the implementation _in some implementation dependent way_.

(Of course one could argue that there are no portable Scheme programs at 
all but I'm not going down that way now...)

> Spanky will require all non-standard libraries to be part
> of the same file that includes the top-level program.
> Other R6RS-conforming systems may not allow this.  Hence
> programs that rely on non-standard libraries are not
> portable.

Why wouldn't other implementation support this? Is it forbidden/not 
recomended in the draft?

Btw who/what is Spanky? For some reason I feel reluctant to google for 
that word.

> This isn't fatal, because the proof above establishes the
> non-portability of program representations.  There remains
> the possibility of a conceptual level on which programs
> might be portable in concept.

Are you saying the same thing as I am? I fail to understand the meaning 
of the word "concept" in your last sentence. English is not my native 
language.

/Mikael