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microsoft / TypeScript

TypeScript is a superset of JavaScript that compiles to clean JavaScript output.
https://www.typescriptlang.org
Apache License 2.0
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Language service: open Type.id #5687

Open fsoikin opened 8 years ago

fsoikin commented 8 years ago

I am using language service to "traverse" the program, and I would like very much to "remember" which types and symbols I already saw, and to cache my computation results for them. Performance boost and avoiding infinite loops.

The compiler very helpfully supplies id for Type, Symbol and Node, and it seems to be "really, really" unique for symbols and nodes, and "relatively unique" (i.e. within a given typechecker) for types.

The problem is, however, that, unlike nodes and symbols, types hide their ids behind the "internal" qualifier and the lack of accessor function, making them not legally visible to me as a consumer of the language service. Of course, this being JavaScript, nothing prevents me from accessing them anyway, and that is what I currently do, but this is not ideal, because I am not protected from the code evolution in the future.

So it seems to me that nothing stands in the way of adding a getTypeId method to the typechecker, unless I'm missing something very important.

ahejlsberg commented 8 years ago

Correct, symbol/node ids are globally unique whereas type ids are unique only to a particular type checker instance. I would be fine with a PR to add a getTypeId method with the caveat that you can only ever compare type ids from the same type checker instance.