Comment by mattmein

Data structure + algorithm is a valid way of building large programs. That is basically how Clojure is designed, and it works pretty well for big applications.

Functional programming in aviation: https://m.youtube.com/watch?v=0x3EIqBrZxw

Functional programming in banking: https://www.finextra.com/newsarticle/36297/nubank-buys-firm-...