Well, let's look at the case of Facebook Messenger's webapp, which is written in BuckleScript (now ReScript), a language based on OCaml. That's about as solid a

Well, let's look at the case of Facebook Messenger's webapp, which is written in BuckleScript (now ReScript), a language based on OCaml. That's about as solid as you can get academically. Here's what they said:[1] > Full rebuild of the Reason part of the codebase is ~2s (a few hundreds of files), incremental build (the norm) is <100ms on average. The BuckleScript author estimates that the build system should scale to a few hundred thousands files in the current condition. > Messenger used to receive bugs reports on a daily basis; since the introduction of Reason, there have been a total of 10 bugs (that's during the whole year, not per week)! * > Most of the messenger core team's new features are now developed in Reason. Dozens of massive refactors while iterating on ReasonReact. Refactoring speed went from days to hours to dozens of minutes. I don't think we've caused more than a few bugs during the process (counted toward the total number of bugs). In a high-velocity codebase, modularity is the name of the game. And you will be hard-pressed to find languages outside the ML family which are that good at modularity. OCaml is just about the only industrial-ready language in this space. [1] https://reasonml.github.io/blog/2017/09/08/messenger-50-reason https://reasonml.github.io/blog/2017/09/08/messenger-50-reas...