Can we make a TypeScript parser with this?

[trusktr]

Looking to make a language that is a superset/subset of TypeScript syntax, but with a different type checking implementation, and not JS output. Would langium be suitable for making a TS parser?

[msujew]

We've build some TypeScript like languages in the past (closed-source) with Langium. While some language/parser features are not completely trivial to implement (such as template strings), Langium should be capable of dealing with that fairly well.

There will be a lot of work on the scoping/type system level you'll need to do, but I imagine that Langium will serve fairly well for this task. Someone created an EBNF grammar of TypeScript a while back. It's not up to spec (since it's from 2014) but it should well as a starting point. I would also recommend to take a look at the langium-lox repo, which shows how to implement scoping and type system support for a Langium based language.

[trusktr]

I'm reading the article, and it is interesting. Thanks for writing that!

Indeed I saw Langium's overview, very enticing.

If we roll with Langium, would it be possible to write our grammar using Chevrotain syntax (with the plugins and things Langium adds I imagine) instead of generating from a grammar language?

[msujew]

Unfortunately not. The information that Langium is using to provide all of the advanced features (AST generation, cross reference resolution, LSP services, etc.) comes straight from the annotated grammar. There's no pure programmatic way of using Langium.

[luan-xiaokun]

We've build some TypeScript like languages in the past (closed-source) with Langium. While some language/parser features are not completely trivial to implement (such as template strings), Langium should be capable of dealing with that fairly well.

I'm interested in how to resolve template-related ambiguities, since the language I'm working with also has this template ambiguity. For example, A<B>(C) can be parsed as a template function call, and can also be parsed as a nested comparison. Could you hint at how to achieve this (if possible)?

[msujew]

@luan-xiaokun I think this warrants it's own discussion in this forum, since it's a bit more complicated. Do you mind creating one? By the way with "template strings" I mean stuff like `label: ${value}`, which require some changes in the tokenizer.

[luan-xiaokun]

Sure, I just started a new discussion in #921