On 23-02-2023 09:51, Dr. Arne Babenhauserheide wrote:
>> Thinking a bit more about it, it should be possible to special-case
>> Guile's interpretation of "#!" such that "#!r6rs" doesn't require a
>> closing "!#".  (Technically backwards-incompatible, but I don't think
>> people are writing #!r6rs ...!# in the wild.)
> Do you need the closing !# if you restrict yourself to the first line?

I thought so at first, but doing a little experiment, it appears you 
don't need to:

$ guile
scheme@(guile-user)> #!r6rs
(display "hi") (newline)

(output: hi)

Apparently Guile already has required behaviour.

>>> Still doesn't really address the problem though, as Scheme scripts (or
>>> scripts in another language) may need to start with a shebang and
>>> "#!lang" or "#lang" is not a valid comment in all languages.  (E.g., I
>>> don't think it's valid Pascal, though I only have read some Pascal
>>> code, I haven't looked at the specification.)
>> I think itmust be ignored in all languages that work as scripts in
>> POSIX. So I would expect that support for ignoring #!... in the first
>> line is very widespread.

The problem is that not all languages were made with POSIX-style scripts 
in mind, e.g. Pascal, BASIC and Java (*).

Greetings,
Maxime.

(*) Java actually allows "#!", but only in 'Shebang' files (see: 
https://openjdk.org/jeps/330#Shebang_files).  It remains invalid to put 
a '#!java' line in files with a class definition that is supposed to be 
found by Java's class loaders and compiler (in Guile terms, the source 
code of a module).