Multiple modules per file

[Paul Backus]

On Monday, 20 June 2022 at 15:48:08 UTC, Dennis wrote:
> What if you could just concatenate .d files?
>
[...]
> Other files can only `import pkg`, since the compiler can't 
> find e.g. `pkg/sub.d`.

Well, presumably you could do it if you passed `pkg.d` explicitly 
on the command line. But it wouldn't work with `dmd -i` (and 
probably not with dub either).

This seems to me like a feature where the number of ways to use 
it right (e.g., for package-internal modules that aren't intended 
for outside use) is much smaller than the number of ways you 
could potentially shoot yourself in the foot with it. If we adopt 
this feature, I expect we'll end up getting a regular stream of 
questions in the Learn forum where someone asks "why doesn't my 
project build?", and the answer is "you need to put your modules 
in separate files."

You could mitigate the issue by requiring that all modules in a 
file belong to the same package, but then you lose out on some of 
the desirable godbolt/run.dlang.io use cases, so it's not a clear 
win.