Joel de Guzman wrote:

It should work, but the savings in compile time will be minimal. If you want to reduce compile and build time, follow the example in the compiler tutorial from calc7 up. The trick is to modularize your grammars and put the definitions in separate cpp files (TUs).

I think I start getting how it works. However, the dependency between statement and expression is not circular in calc7: expression seems to have no knowledge about statement. So if my dependency is circular (like e.g. expression and factor in calc2_ast), is it possible to separate them, as you suggest? Also, is there any documentation for calc7 or about TUs (what does TU mean?)? Again, many thanks for your kind answers.