Re: use-modules in gexps

[Ricardo Wurmus <rekado@elephly.net>]

Ludovic Courtès <ludo@gnu.org> writes:

>> I wondered if perhaps we could add a G-expression compiler for module
>> imports, so that instead of
>>
>> (with-imported-modules (source-module-closure '((my module)))
>>   #~(begin
>>      (use-modules (my module))
>>      …))
>>
>> we would do
>>
>>   #~(begin
>>      #$(use-modules (my module))
>>      …)
>>
>> which would have the effect of adding (my module) — or the module
>> closure – to the list of modules needed by the current G-expression.
>
> I think the syntax should be different because #$/ungexp has a different
> meaning.  However, that would leave open the question of how to select
> the subset of the module’s closure you want to import, etc.
>
>> Can a G-expression compiler help accumulate state (e.g. by making
>> G-expressions values in the state monad) or can it only be compiled down
>> to a value at the current location?
>
> The latter.  What state would you want to accumulate?

When I wrote “state” I had the list of modules encountered in mind, so
that it would be possible to collect all marked instances of
“use-module” and hoist them to the top, in effect doing automatically
what is achieved manually by using “with-imported-modules” with a list
of modules.

--
Ricardo