Why should file names intended for executables be valid identifiers?

[Alex Parrill via Digitalmars-d-learn]

On Tuesday, 15 December 2015 at 03:31:18 UTC, Shriramana Sharma 
wrote:
> I expect it should not be difficult for the compiler to see 
> that this D file is not a module being imported by anything 
> else or even being compiled to a library which would need to be 
> later imported. In which case, why does it insist that the file 
> should be given a valid module name?

All files in D are modules. The only thing special about the 
"main" module is that it exports a function called `main`, which 
druntime calls at startup.

It's like asking why you need to have a class in Java that only 
contains `public static void main(...)`, instead of just having 
the main function itself; it's simply how D is designed, and it 
reduces the number of special cases.

Though after compiling, module names are irrelevant; you can name 
the binary whatever you want: `dmd -o whatever-filename.exe 
my_module.d`

Name mangling is irrelevant; you can't have a dash in the module 
name because it would make certain code ambiguous (ex. 
`foo.my-module.bar`: is one module field reference or a 
subtraction between two field references?)