Razzeee/tree-sitter-elm

Tree sitter implementation for elm

88

stars

484

commits

JavaScript

primary language

Sep 3, 2026

updated

elm-tooling.github.io/tree-sitter-elm/
elm
hacktoberfest
highlighting
parsing
tree-sitter

README

Build Status

Elm tree sitter

Why am I doing this?

I believe that Elm would greatly benefit from better tooling, the ultimate goal is to write a language server integration. This is a possible building block for that.

What it brings to the table:

  • Very fast parsing, should enable parsing on each keystroke.
  • Resilient, even if you use wrong syntax, most of the file should still be recognized alright.
  • Should also be useful to the elm atom maintainers, as atom is using tree sitter as the new default for code highlighting (our ast might be too expressive). Highlight implementation still needs to be done if wanted.

What is this tested with?

This is tested against the tests included in the repo and:

So it should work fine for a fair amount of code. What's not tested right now is behavior in error cases.

Thanks

Very very big thanks goes out to @klazuka and the people of intellij-elm as I basically stole how they're creating their parser minus the GLSL implementation.

Want to help?

Help writing some tests or simply find valid elm files, that fail parsing. Test are located in the test folder and separated in parser tests and highlighting tests.

Contributors

razzeee

403 commits

dsimunic

16 commits

dependabot[bot]

14 commits

harrysarson

14 commits

Razzeee/tree-sitter-elm

Tree sitter implementation for elm

88

stars

484

commits

JavaScript

primary language

Sep 3, 2026

updated

elm-tooling.github.io/tree-sitter-elm/
elm
hacktoberfest
highlighting
parsing
tree-sitter

README

Build Status

Elm tree sitter

Why am I doing this?

I believe that Elm would greatly benefit from better tooling, the ultimate goal is to write a language server integration. This is a possible building block for that.

What it brings to the table:

  • Very fast parsing, should enable parsing on each keystroke.
  • Resilient, even if you use wrong syntax, most of the file should still be recognized alright.
  • Should also be useful to the elm atom maintainers, as atom is using tree sitter as the new default for code highlighting (our ast might be too expressive). Highlight implementation still needs to be done if wanted.

What is this tested with?

This is tested against the tests included in the repo and:

So it should work fine for a fair amount of code. What's not tested right now is behavior in error cases.

Thanks

Very very big thanks goes out to @klazuka and the people of intellij-elm as I basically stole how they're creating their parser minus the GLSL implementation.

Want to help?

Help writing some tests or simply find valid elm files, that fail parsing. Test are located in the test folder and separated in parser tests and highlighting tests.

Contributors

razzeee

403 commits

dsimunic

16 commits

dependabot[bot]

14 commits

harrysarson

14 commits

Languages

JavaScript

57.2%

C

31.1%

Shell

6.1%

Tree-sitter Query

4.0%

Elm

1.6%