Re: [Scheme-reports] Formal Comment: clarify library loading rules
Richard Kelsey 02 Jul 2012 15:31 UTC
Date: Sun, 01 Jul 2012 19:04:37 -0400
From: Aaron W. Hsu <arcfide@sacrideo.us>
John Cowan <cowan@mercury.ccil.org> wrote:
> Richard Kelsey scripsit:
>> Regardless of the number of times that a library is loaded,
>> each program or library that imports bindings from a library
>> will receive bindings from a single loading of that library,
>> of the number of the number of import or cond-expand forms
>> in which it appears.
>
> This is a substantive change, so ballot ticket #441 filed.
I would like to point out that this is incompatible with existing
practice on Scheme implementations which instantiate a unique
library instance for every phase of expansion. Putting this
requirement into WG1 would preclude WG2 from considering or
allowing library systems which use multiple instantiation semantics
for libraries.
Right. I withdraw my suggestion of the above text.
What I was trying to do was to make it possible to import the same
binding, from the same instantiation, under multiple names. A more
direct way to do this would be to add
(alias <import set> (<identifier1> <identifier2>) ...)
which makes the binding of <identifier1> available as both <identifier1>
and <identifier2>.
As a side note this would make
(rename <import set> (<identifier1> <identifier2>) ...)
equivalent to
(drop (alias <import set> (<identifier1> <identifier2>) ...)
<identifier1> ...)
-Richard Kelsey
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