Custom Parser with 3.2

[Emanuele Ianni <dierre@xxxxxxxxx>]

Hi, I need to debug my grammar and it would be really helpful to see,
in addition to the output provided by the Custom Lexer, the output
provided by the Parser while it's building the AST. Basically I want
to be able to see the reducing happening while scanning the tokens. Is
it possible? I tried to follow the appendix of the thesis to build the
custom parser but it's not working. Apparently I can't use token.apply
inside the filter method.
Thanks!