* Module scoping
  This document contains some notes on how the implementation of module scoping
  is supposed to work.

** Import statements
   What happens when we see:
   #+begin_example
   import Data.Nat
   #+end_example
   All symbols *defined* in =Data.Nat= become available in the current module
   through qualified names. I.e. =Data.Nat.zero=.

** Open statements
   What happens when we see:
   #+begin_example
   open Data.Nat
   #+end_example
   All symbols *defined* in =Data.Nat= become available in the current module
   through unqualified names. I.e. =zero=.

   =using= and =hiding= modifiers are handled in the expected way.

** Nested modules
   What happens when we see:
   #+begin_example
   module Local;
   ...
   end;
   #+end_example
   We need to answer two questions.
   1. What happens after =module Local;=. Inside =Local= *all* symbols that were
      in scope, continue to be in scope.
   2. What happens after =end;=. All symbols *defined in* =Local= are in scope
      through qualified names. One can think of this as the same as importing
      =Local= if it was a top module.