How to import from the parent module?

[nicolo-ribaudo]

Module fragments can refer to each other, but it might also be useful to provide some syntax to allow importing the outer module. For example:

export function add(x, y) {
  return x + y;
}

export module test {
  import { add } from super; // 'super' to refer to the outer module
  
  assert(add(0, 2) === 2);
  assert(add(1, 2) === 3);
}

There is also the option of not reserving any specific syntax, and modules would have to write the explicit specifier of the outer module:

// ./math.js

export function add(x, y) {
  return x + y;
}

export module test {
  import { add } from "./math.js";
  
  assert(add(0, 2) === 2);
  assert(add(1, 2) === 3);
}

Note that if we provide some syntax to do it, it's more useful to refer to the top-most module rather than to its direct parent:

export const x = 1;

module M1 {
  export const y = 2;

  module M2 {
    import { y } from M1; // it's easy to import outer module declarations
    import { x } from ...; // how to import the top-level module?
  }
}

This use case was initially suggested at tc39/proposal-module-expressions#34.

[littledan]

I think this is worth keeping in mind, but as discussed in that thread, I'd be OK with the initial version of this proposal simply not having syntax for that case.