Local modules

Local modules are lexically scoped. They can be defined at the top level of a stream. They can be referenced immediately following the directive in which they are defined, up until the end of the stream.

Local modules always have a symbolic name given at the point of definition, also known as a binding.

Stream-level bindings are mutable.

(:$ion module foo // <-- Top-level module `foo`
  (macros
    (quux Quux)))

(:$ion module foo // <-- Redefines the top-level binding `foo`
  (macros
    (quuz Quuz)))

Local modules inherit their spec version from the enclosing scope. Local modules automatically have access to modules previously declared in their enclosing scope using module or import.

The default module is a local module that is implicitly defined at the beginning of every stream.