foo.ts

// == one.ts ==

export interface SomethingPublic {
  foo(a: number): number;
}

// == two.ts ==

// error: SomethingPublic is not visible here
// this doesn't help:
/// <reference path="one.ts" />

class Foo implements SomethingPublic {
  foo(a: number): number {
    return a + 1;
  }
}

export createFoo(): Foo {
  return new Foo();
}

// == mything.ts ==

export * from './one';

// == example.ts ==

import * as MyThing from './mything';

let foo = MyThing.createFoo();
// MyThing.Foo -> not defined/exported here
foo.foo(5);