Handling AssemblyScript input files

(Continuing from https://github.com/Microsoft/TypeScript/issues/10939)

I'd like to add another use case:

AssemblyScript. :)

It could be handy to have both .ts and .as files, to disambiguate the two.

For example, at the moment I have both src/ts/ and src/as/ folders to disambiguate the two.

It would also then be possible to have both some-project/index.ts and some-project/index.as, and which one is being imported in import foo from 'some-project' would depend on the file type.

The AssemblyScript guys are currently discussing how to make Node-style module resolution work, with the idea of an asmain field in package.json similar to main but for AS code, or defaulting to assembly/index.ts when there's no asmain field, because of ambiguity between AS and TS files.

Having an assembly/ folder at the root of a project (IMO) doesn't follow the convention in the web/JS community of having a src folder for sources.

If not allowing custom extensions for this, would the TypeScript team rather add another official extension? Perhaps even official AS types into the mix for such files (i32, i64, f32, etc, instead of just number)?

Start with the linked TypeScript issue #10939 and AssemblyScript issue #448, then review the proposed .as extension, src/ts and src/as layout, and the package.json asmain idea. Done would require a decided approach for distinguishing TypeScript and AssemblyScript inputs and resolving imports between them.