>> In Racket, in the initial configuration of the reader when reading a file, "`#!` is an alias for `#lang` followed by a space when `#!` is followed by alphanumeric ASCII, `+`, `-`, or `_`." (See <https://docs.racket-lang.org/reference/reader.html#%28part._parse-reader%29>.) [...] > (Guile does not handle `#!r6rs` properly, presumably because of the legacy `#!`/`!#` block comments. I think this should be a surmountable obstacle, though, especially since Guile does support standard `#|`/`|#` block comments.)
> 
> ‘#! ... !#’ comments aren't legacy; they exist to allow putting the shebang in the first line of a script, and to pass additional arguments to the Guile interpreter (see: (guile)The Top of a Script File) (*).  As such, you can't just replace them with #| ... |# (unless you patch the kernel to recognise "#| ..." as a shebang line). [...]
> 
> Furthermore, according to the kernel, #!r6rs would mean that the script needs to be interpreted by a program named 'r6rs', but 'guile' is named 'guile', not 'r6rs'.  (I assume this is in POSIX somewhere, though I couldn't find it.)
> 
> (This is an incompatibility between R6RS and any system that has shebangs.)

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.)

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.)

Greetings,
Maxime.