[o11c]

Not sure, but I at least am certainly aware of possibilities that such writeups exclude.

In particular, you can do (a subset of) the following in sequence:

* write your own grammar in whatever bespoke language you want

* compose those grammars into a single grammar

* generate a Bison grammar from that grammar

* run `bison --xml` instead of actually generating code

* read the XML file and implement your own (trivial) runtime so you can easily handle ownership issues

In particular, I am vehemently opposed to the idea of implementing parsers separately using some non-proven tool/theory, since that way leads to subtle grammar incompatibilities later.