Solved autoformatting for Justfiles

[ficd0]

TL;DR: Use a script to write Helix buffer to a temp file, use just to format that, then print it to stdout so Helix accepts it.

As seen in issue #9703 , there's an issue with formatting the justfile. In Helix, the formatter command must take the document as input on stdin and print the formatted document to stdout. just --dump doesn't work like this; it reads from the justfile that's on the disk, and outputs the formatted version to stdout. Therefore, it can only effectively format the version of the file that's saved. If you have auto-format=true, then you won't actually ever be able to write your changes, since the "formatting" always reverts it to the state that's written to disk!

I wrote a Fish script to work around this. Basic idea is to write stdin to a temporary file first. just has a --justfile option to specify the justfile path; so we give the temp path instead, so --dump formats the actual contents of our Helix buffer, not the saved justfile. Here it is:

function justfmt --description "STDIO Justfile formatter"
    set -l temp (mktemp)
    cat >$temp
    just --justfile $temp --dump
    rm $temp
end

Then in languages.toml I have the following:

[[language]]
name = "just"
auto-format = true
formatter = { command = "fish", args=["-c", "justfmt"] }

Here's an example of a Bash script that does the same:

#!/bin/sh
TEMP="$(mktemp)"
cat > "$TEMP"
just --justfile "$TEMP" --dump
rm "$TEMP"

[rhogenson]

Does just --justfile /dev/stdin --dump work?

[ficd0]

Yes it does, thanks! Sadly this solution isn't cross-platform either so we can't contribute it to the default config

[eli-yip]

I also write a rust wrapper to do this: https://github.com/eli-yip/just-formatter

[ficd0]

that looks great! I'll give it a shot

[ficd0]

Works like a charm. I just opened a PR #13323 to add this as the default to Helix. Great work!