Any way to declare a nest class structure in typescript?

This seems like it has been fixed in versions 0.9.1.1 and later. You just have to create a module with the same name as the class where you want to nest types, and put your nested types in it.

More concretely, this is how you do it:

declare module a
{
    class b
    {
    }

    module b
    {
        class c
        {
        }
    }
}

var myB = new a.b();
var myC = new a.b.c();

This works as well when nesting types in typescript code with the export keyword:

export module a
{
    export class b
    {
    }

    export module b
    {
        export enum c
        {
            C1 = 1,
            C2 = 2,
            C3 = 3,
        }
    }
}

As mentioned by the user @recursive in the comments below, the order of declaration is important. So the class definition must be located before the module with the nested types.