[bug#41253] [PATCH v3] guix repl: Add script execution.

[Ludovic Courtès]

Hello Konrad,

Konrad Hinsen <konrad.hinsen@fastmail.net> skribis:

>> It cannot be used as a shebang, can it?
>
> It can. And that might be worth documenting. Here's an example:
>
>   ===== File foo.scm =========================================
>   #!/usr/bin/env -S guix repl
>   !#
>   (use-modules (ice-9 format))
>
>   (format #t "foo called with arguments: ~s\n"(command-line))
>   ===== End of file foo.scm ==================================
>
>   hinsen@guix ~$ ~/foo.scm a b c
>   ;;; note: source file /home/hinsen/temp/foo.scm
>   ;;;       newer than compiled 
> /home/hinsen/.cache/guile/ccache/3.0-LE-8-4.2/home/hinsen/temp/foo.scm.go
>   foo called with arguments: ("/home/hinsen/temp/foo.scm" "a" "b" "c")

Nice!

> The ugly part is that the script needs to be called with '–' as its
> first argument if any of the following arguments start with dashes:
>
>   hinsen@guix ~$ ~/foo.scm -- --help
>   ;;; note: source file /home/hinsen/temp/foo.scm
>   ;;;       newer than compiled 
> /home/hinsen/.cache/guile/ccache/3.0-LE-8-4.2/home/hinsen/temp/foo.scm.go
>   foo called with arguments: ("/home/hinsen/temp/foo.scm" "--help")
>
> That could be fixed at the price of a command line interface for "guix
> repl" that deviates a bit from Guix conventions. For example,
> is there's a file name argument, pass all arguments following it to the
> script, eliminating the need for –.

Yes, that makes sense to me.

> I'll try that in a v4, and also take into account all your remaining
> remarks. Just one note on the examples:
>
>>> +@example
>>> +$ guix repl -- my-script.scm --input=foo.txt
>>> +@end example
>>
>> I’d remove “$” from the examples.
>
> There are many examples in guix.texi with $, and also many without. Plus
> some with # as the command line prompt.

Yeah, the manual is kinda inconsistent, and I’m self-inconsistent to
tell the truth.  :-)

I’ve come to the conclusion that snippets that contain only input should
be written without a prompt, for easier copy/pasting.

(I’ve seen Python documentation where JS magic allows people to toggle
prompt display, I find it nice.)

> A technical question: is there any way to suppress the error message
> about the source being newer than the cached version? This is really
> annoying when running scripts.
>
>>   hinsen@guix ~$ ~/foo.scm a b c
>>   ;;; note: source file /home/hinsen/temp/foo.scm
>>   ;;;       newer than compiled 
>> /home/hinsen/.cache/guile/ccache/3.0-LE-8-4.2/home/hinsen/temp/foo.scm.go
>>   foo called with arguments: ("/home/hinsen/temp/foo.scm" "a" "b" "c")

I guess ~/.cache/…/*.go exists because you first ran “guile foo.scm”,
no?  In that case, you can simply remove that .go file.

The ‘guix’ command turns off auto-compilation so ‘guix repl’ scripts
would always be interpreted, for better or worse.

Thanks,
Ludo’.