lemon binary package in Ubuntu Focal riscv64

 Lemon is an LALR(1) parser generator for C or C++. It does the same
 job as bison and yacc. But lemon is not another bison or yacc
 clone. It uses a different grammar syntax which is designed to reduce
 the number of coding errors. Lemon also uses a more sophisticated
 parsing engine that is faster than yacc and bison and which is both
 reentrant and thread-safe. Furthermore, Lemon implements features
 that can be used to eliminate resource leaks, making is suitable for
 use in long-running programs such as graphical user interfaces or
 embedded controllers.

Source package