Helix editor for Elixir Development

xiaoqiang

These past few days, I’ve tried switching from Neovim to Helix, and so far the experience has been great. Compared to neovim, which requires multiple plugins and configurations, Helix requires very little configuration to start using it for Elixir. Plus, it has a great shortcut key prompts, so if you’ve used vim before, you can quickly get used to it.

In addition to its out-of-the-box features, one of my favorite features of Helix is its multi-selection editing!

Prerequisites:

Ensure that elixir-ls is installed and in your path. On macOS, you can use brew install elixir-ls.

Put the following configuration in .config/helix/languages.toml, and happy coding!

[[language]]
name = "elixir"
scope = "source.elixir"
injection-regex = "elixir"
file-types = ["ex", "exs"]
roots = ["mix.exs"]
auto-format = true
diagnostic-severity = "Hint"
comment-token = "#"
indent = {tab-width = 2, unit = " "}
language-server = {command = "elixir-ls"}

66 comments

#deployment #code-editors #learning-elixir

18 15938 66

2025-08-02 18:36:34 UTC

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dimitarvp

Can it do the template coloring in the same files i.e. two different syntaxes in one file? The HEEX stuff?

Post #1

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xiaoqiang

It is possible because their syntax highlighting uses tree-sitter.

Furthermore, I suggest updating the Elixir configuration to support specific features of the language server in heex. Additionally, I discovered that my understanding of the “injection-regex” configuration item was incorrect, and we may not require it.

[[language]]
name = "elixir"
scope = "source.elixir"
file-types = ["ex", "exs", "heex"]
roots = ["mix.exs"]
auto-format = true
diagnostic-severity = "Hint"
comment-token = "#"
indent = {tab-width = 2, unit = " "}
language-server = {command = "elixir-ls"}

Post #4

tcoopman

I’ve figured out a great trick, to be able to run mix test with filename and line numbers as longs a https://github.com/helix-editor/helix/pull/6979 is not merged yet.

I’m using zellij, wezterm and helix of course.

I use this script to parse the file and line number from the terminal:

        set -x

        status_line=$(wezterm cli get-text | rg -e "(?:NOR\s+|NORMAL|INS\s+|INSERT|SEL\s+|SELECT)\s+[\x{2800}-\x{28FF}]*\s+(\S*)\s[^│]* (\d+):*.*" -o --replace '$1 $2')
        filename=$(echo $status_line | awk '{ print $1}')
        line_number=$(echo $status_line | awk '{ print $2}')

        case "$1" in
          "file")
            mix test $filename
            ;;
          "line")
            mix test $filename:$line_number
            ;;
          "all")
            mix test
            ;;
        esac

Source: nix-hour/code/29/home.nix at dfe7bfde9dc117b3f2d583eb418f2376f141757a · tweag/nix-hour · GitHub

save it somewhere as executable.

I add these key-bindings in helix:

[keys.normal."t"]
a = ":run-shell-command zellij run -d right -- helix-wezterm-script.sh all"
f = ":run-shell-command zellij run -d right -- helix-wezterm-script.sh file"
l = ":run-shell-command zellij run -d right -- helix-wezterm-script.sh line"

And now you can run tl in a test file and it will run the test on that line in split.

Hopefully this is useful to someone.

Post #51

joges

I noticed that the syntax highlighting for HEEX files was not correct with just adding “heex” to the file types but adding “html.heex” did the trick for me:

[[language]]
name = “elixir”
scope = “source.elixir”
injection-regex = “elixir”
file-types = [“ex”, “exs”, “html.heex”]
roots = [“mix.exs”]
auto-format = true
diagnostic-severity = “Hint”
comment-token = “#”
indent = {tab-width = 2, unit = " "}
language-server = {command = “elixir-ls”}

Post #35

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nulltree

Depends on what plugins you’d miss, I guess. For me the biggest current paper cut t is it not automatically recognizing external file changes.

As to the plugin system’s release - it appears to be somewhat close, the creator recently remarked he primarily wants some more code reorganization to be willing to release it under a feature flag.

Post #66