- every non-trivial software is a compiler
- every non-trivial software is a database
Every non trivial software have to read/parse/manipulate/store a lot of data. I think it ultimately permit to simplify thinks to just admit that we are doing a specialized database/compiler. The fact that input data are coming from file, database, network, command line or the code itself and are going to files, database or network is just an implementation detail.