* macro/module system with phases ( https://www.cs.utah.edu/plt/publications/macromod.pdf )

* submodules ( http://www.cs.utah.edu/plt/publications/gpce13-f-color.pdf )

* Languages as modules (i.e. the #lang mechanism ) ( http://www.ccs.neu.edu/racket/pubs/pldi11-thacff.pdf )

* Documentation system that links identifiers to documentation (respecting the scope)

  ( http://docs.racket-lang.org/ )