Future work
Just some ideas... things to implement or to think about...
printer for EXTEND_PRINTER
There is a syntax "EXTEND_PRINTER" but the corresponding printer is missing.
extensible lexers
Extensible lexers would be an interesting extension. And possibly lexers using regular expressions (extensible if possible, otherwise as a different module).
utf-8
The Camlp5 lexer for OCaml programs (module Plexer) allows utf-8 characters. Since utf-8 seems to have some success among unicode formats, perhaps a reflection to add greek characters and/or real utf-8 arrows in the syntax (in particular in types) would be interesting.
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