Languages evolve too! Changing the software time scale

Humans will have to live with software for a long time. As demonstrated by the Y2K problem, computer professionals used a wrong time scale when thinking about software. Large software products live much longer than expected. It took a few decades to the research community to admit that software engineering was not only about software development, but above all, about software evolution. However, most academics still consider languages as immutable artefacts. Language/software co-evolution issues are still neglected. Migration issues are however commonplace in software industry. It is therefore time to recognize that languages evolve too. Languages are integral parts of software products. Languages are software too. This paper surveys a few models of evolution taking decades and centuries as time-scales. Then programming languages evolution over the last half-century is sketched by means of a metamodel movie.