Support Pluggable, 3rd-party Type Systems

[jednano]

There's a library written by @gcanti called tcomb-ats, which is a 3rd-party assertion library for AtScript. Now that AtScript has been replaced with TypeScript, does that change the TypeScript Design Non-Goals in any way? Would support for 3rd-party assertion libraries like tcomb-ats be possible?

If configured the same way, it would go in the tsconfig.json file as such:

{
  "typeAssertionModule": "path/to/tcomb-ts"
}

[danquirk]

As far as I can tell this is basically asking for a pluggable type system, which essentially no languages do (well). This doesn't look like an assertion library (in the sense of common uses of the term like chai, should, etc), it looks like an entirely new set of primitive types and assignability rules. This isn't something we'd support.