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From: Bart <bc@freeuk.com>
Newsgroups: comp.lang.c
Subject: Re: question about linker
Date: Wed, 4 Dec 2024 15:46:55 +0000
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On 04/12/2024 12:29, Waldek Hebisch wrote:
> Bart <bc@freeuk.com> wrote:
>> You've never used my scheme.
> 
> Your scheme, not.  But you should understand that when speaking
> about module systems C is an outlier, having almost no support
> for modules.  Some languages, like C++ and Lisp go half way,
> providing namespaces but rest is up to programmer.  Other do
> more.  By now classis is _logical_ separation into interface
> and implementation, which seem to be absent from your system.

It is there, but at a different boundary.

My language is intended for whole program compilation. There are no 
interfaces between modules (that is, a file listing the exports of a 
module, separately from the implementation).

Because the compiler can see (and will compile) the actual implementation

Such interface files exist between programs, which usually means between 
a main program and the libraries it uses, which are generally 
dynamically loaded.

To that end, when compiling a set of modules into a library, the 
compiler can generate a suitable interface file (I used to call them 
exports files).

This part is poorly developed, as it is little used, but it can create 
such files for my two languages, and /could/ generate them for C. There, 
it would take the form of a header file.

Example library, called fred.m:

   export func add3(int a,b,c)int =
       a+b+c
   end

Create the DLL and interface:

   c:\mapps>mm -dll fred
   Compiling fred.m to fred.dll
   Writing exports file to fred_lib.m

The interface file produced (fred_lib.m):

   importdllfred =
     func add3(i64 a,b,c) => i64
   end

The C version would be:

   extern i64 add3(i64, i64, i64);

Back to my version, I can use that DLL like this:

   module fred_lib

   proc main =
       println add3(10,20,30)
   end

Compile and run that:

   c:\mapps>mm -r test
   Compiling test.m to test.(run)
   60

As a bonus, this simple example will also run unchanged in my dynamic 
scripting language; I just need to change the file extensions. So I can 
trivially create native-code functions to call from dynamic code.

But in practice, more work is needed.