File type aliases

[aral]

Hi folks,

Is there a way to configure Helix with file type aliases so that, say, files with .my-custom-extension are interpreted as, say, JavaScript?

(I’ve been looking through the docs but haven’t been able to see anything but wondering if there’s some undocumented way at the moment – I might also have missed it in the docs.)

Use case

I want files with the .page extension to be seen as JavaScript files. I want to do this without adding a separate language and grammar definition and tree-sitter queries (and thereby basically adding a redundant copy of the information that’s already in the JavaScript definitions).

Suggested implementation

If there isn‘t a way to do this, here’s my initial (naive) suggested implementation:

In languages.toml (e.g., for NodeKit aliases):

[[alias]]
name = "nodekit"
file-types = ["page"]
language = "javascript"

The result of this would be to effectively extend (concatenate) the file-types array of the JavaScript language definition with the entries in the aliases file-types array.

Thoughts? :)

[eulerdisk]

You can do this already by putting these lines in your ~/.config/helix/languages.toml:

[[language]]
name = "javascript"
file-types = ["js", "jsx", "mjs", "cjs", "page"]

(Take a look at the languages.toml in Helix repo.)

More info here.

[aral]

@eulerdisk Thanks, that’s a good short-term workaround but it’s an override not an extension. So you have to make sure you keep it updated, say, if the original language itself adds some file types in the future. Also it’s not very maintainable and prone to errors. Aliases would add to the file type mappings instead of replacing them.

In VSCode, for example, you would use a file association mapping: https://code.visualstudio.com/docs/languages/overview#_adding-a-file-extension-to-a-language

I also should have made it clearer that my use case here is to eventually submit those aliases for inclusion in Helix to support a framework I’m working on. And this would create a maintainability issue for Helix for the reasons I mention above.

[kirawi]

You can do:

[[language]]
name = "mylang"
grammar = "javascript"

[aral]

Ah, I’m going to try that out when I’m at my computer @kirawi, thank you :)

I hadn’t realised you can explicitly specify a grammar property when defining a language (I assumed it was based on a naming convention). If that works, it should be all I need. Thanks again :)

[aral]

Were you able to get that to work?

The minimum Helix accepts for a language definition includes scope and root for me. When I tried the following:

[[language]]
name = "nodekit"
scope = "source.nodekit"
roots = []
file-types = ["page", "get", "post", "delete", "patch"]
language-server = { command = "typescript-language-server", args = ["--stdio"], language-id = "javascript" }
grammar = "javascript"

I got:

thread 'main' panicked at 'Could not parse queries for language "nodekit". Are your grammars out of sync? Try running 'hx --grammar fetch' and 'hx --grammar build'. This query could not be parsed: QueryError { row: 0, column: 1, offset: 1, message: "required_parameter", kind: NodeType }', helix-core/src/syntax.rs:379:43
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

(Which leads me to believe that its doesn’t automatically use the tree-sitter queries for JavaScript.

[aral]

Mind you, having just written that, I see that the language definition for jsx, for example, is written exactly as you suggest and doesn’t have its own grammar so but it does have its own tree-sitter queries in runtime/queries/jsx 🤔

[aral]

Aha, and all the query files just have:

; inherits: javascript

in them. So I’m going to try doing the same :)

[aral]

Eureka! That works. Thanks for your help @kirawi, appreciate it :)

For anyone else reading this, here’s the language definition I ended up with:

[[language]]
name = "nodekit"
scope = "source.nodekit"
injection-regex = "nodekit"
file-types = ["page"]
roots = []
comment-token = "//"
language-server = { command = "typescript-language-server", args = ["--stdio"], language-id = "javascript" }
indent = { tab-width = 2, unit = "  " }
grammar = "javascript"

And I simply copied runtime/queries/jsx to runtime/queries/nodekit. All the tree-sitter queries files there simply have the following content:

; inherits: javascript