Once you add IDE and REPL support (Which Scala does) you need a storage layer as an optimization. Odersky spends most of the lecture time detailing resulting pe

Once you add IDE and REPL support (Which Scala does) you need a storage layer as an optimization. Odersky spends most of the lecture time detailing resulting performance goals and effects on internals to support these features. This leads him towards a normal-form topology to minimize data duplication, of course, which is why he gave it the title "Compilers are Databases".