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Comment by akdor1154 | Hacker News Reader

I really want to see a cross-shell, declarative language for autocomplete definitions. Does such a thing exist?

On my Christmas holidays I built a little tool that does similar things.

Features I wanted to include originally were

   1 shell completion autogeneration from `--help` texts;
   2 support bash/zsh/fish;
   3 support toml-like description of command arguments.

At the moment I have a tool that generates completions from `--help` messages and supports bash/zsh. I use it daily and it makes me little bit happier.

[1] https://github.com/dim-an/cod

It's called "cod" and doesn't support fish? :(

Why would I need a fish if I already have cod? ;)

Actually when I started this project I used fish as my main shell on laptop and first versions of cod did support fish, but then I decided to focus bash/zsh as they look more popular.

I still want to add fish support when I have some time though. It doesn't look complicated.

The "declarative" part doesn't really make sense IMO, but there are a bunch of links here about having a shell-agnostic system:

https://github.com/oilshell/oil/wiki/Shell-Autocompletion

https://github.com/oilshell/oil/wiki/Projects-Already-Doing-...

https://github.com/mbrubeck/compleat (one of the only grammar-based ones, looks nice but doesn't appear to have been used very much)

There are some discussions about cross-shell autocompletion on the #shell-autocompletion channel of https://oilshell.zulipchat.com/, but it didn't go that far.

The Ion work described in the sibling blog post went the furthest in terms of implementation I think, but I haven't heard anything about it in awhile.

These are awesome, thanks.

By 'declarative' I mean some way of telling the shell how my bin can provide completions itself.

E.g. for the AWS util, I am envisioning something like

    aws ec2 describe-instances --instance-id __INSTANCEID__
    __INSTANCEID__: $(aws ec2 list-instances --query Instance.ID)

Syntax here is not anything like a well thought out proposal, just a demonstration of what I believe to be a shell agnostic method of describing both 'where can I complete?' and 'how can I compete it?'

I wouldn't want to limit myself like that. The best home spun completions I've written will do things like look up values in a database, differ depending on previous arguments, parse some file, etc. These will never fit into a declarative language.

Yes it can. https://news.ycombinator.com/item?id=22500928

https://www.redox-os.org/news/rsoc-ion-ux-2/

https://docs.rs/crate/shellac-server/0.3.1

Shameless plug: https://shellcomp.github.io/

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