[Chicken-users] Fwd: Understanding modules?

[Norman Gray]

Greetings.

Oleg Kolosov also sent the reply below, but accidentally sent it only to 
me and not the list; he's asked me to forward it here.

Thank you Oleg and John, for these explanations.  I won't be back in 
Chicken-land for a couple of days, but as soon as I can I'll aim to 
understand this point well enough to offer a draft of additional text 
for the manual.

Best wishes,

Norman


Forwarded message:

> From: Oleg Kolosov <address@hidden>
> To: Norman Gray <address@hidden>
> Subject: Re: [Chicken-users] Understanding modules?
> Date: Tue, 15 Mar 2016 23:10:20 +0300
>
>
> > On 15 Mar 2016, at 21:28, Norman Gray <address@hidden> wrote:
> >
> >
> > Greetings.
> >
> > ...again, on my second day with Chicken.  I can't easily tell from 
> > the docs what is the idiomatic pattern for usage of Chicken modules.  
> > Can anyone point me to a reference?
> >
> > [ I hope it's useful to ask these somewhat beginner questions. ...
>
> Hello! You've got quite far on your second day. I'll try to clarify a 
> few points.
>
> You are right that unit files are, in fact, just C object files, this 
> feature is CHICKEN specific, not portable and its usage is generally 
> frowned upon. Everything is compiled into single output file with 
> unified global namespace, the standard library is automatically 
> available, you do not need to import anything but the downside is - 
> you will not get compilation warnings for undefined identifiers and 
> such. You can use it for special cases like separate compilation (like 
> in C) or when the sources are partially generated.
>
> The module support in Scheme was standardized some time ago but 
> CHICKEN implementation precedes the standard and have some quirks and 
> special features.
>
> AFAIR the 'import' statement tries to load *.import.scm or *.import.so 
> from <prefix>/lib/chicken/?/ which are generated by 
> 'emit-...-import-library' options. *.import.scm can also be loaded 
> from the current directory or include-paths passed in command line. 
> Having these separate 'import libraries' is very useful when 
> cross-compiling for different architecture because it is not possible 
> to load foreign modules during compilation to check exported names and 
> such.
>
> See the same lib path for <name>.so files. Those <name>.so which have 
> the corresponding <name>.import.so - are externally installed modules 
> which you need to 'use' or 'require-extension'. The rest *.import.so - 
> are modules provided by the CHICKEN itself, which are always loaded 
> with runtime and you need to just 'import' to make them visible in 
> your own modules. Some names are built-in and do not have the 
> corresponding file, these are also 'import only'.
>
> —
> Regards, Oleg
> Art-System

--
Norman Gray  :  https://nxg.me.uk
SUPA School of Physics and Astronomy, University of Glasgow, UK