Doulingo is a language learning platform with over 200 million users. On a daily basis millions of users receive customized language lessons targeted specifically to them. These lessons are generated by a system called the session generator.
Andre Kenji Horie is senior engineer at Doulingo. He wrote about the process of rewriting the session generator, as well as moving from python to scala. and changing architecture all at the same time.
In this episode Andre talks about the reasons for the rewrite, what drove them to move to scala and the experience of moving from one technology stack to another.