menhir binary package in Ubuntu Focal arm64

 Menhir is a LR(1) parser generator for the OCaml programming language.
 It is mostly compatible with the ocamlyacc parser generator provided with
 the OCaml system, and has the following enhancements over ocamlyacc:
  * it accepts LR(1) grammars,
  * it offers parameterized nonterminal symbols as well as a library of
    standard definitions,
  * it explains conflicts in terms of the grammar,
  * it allows grammar specifications to be split over multiple files and
    parametrized by OCaml modules,
  * it produces reentrant parsers.

Source package