Motion shifted to C# around August of last year. Part of the reason, I suspect, is that the CTO (Hi Chander!) is an OCAML fanboy and F# was the most practical platform alternative.

We shifted all new product backend build to C# (because at this time last year, we were still "AI assisted" and deemed F# too foreign for most devs to read well), but all internal tooling was built on F#.

By maybe May of this year? We had multiple F# backend codebases, fully AI generated. Only one person on the entire team had worked with F# by hand. Several things work in F#'s favor even though it has a lot less representation in training: 1) the people that write F# really love F# so the code out in the wild is going to be better quality (hunch), 2) F# is a bit more terse/dense than C# and less noise in context, 3) F# benefits from the same tooling stack, 4) F# type system is still a bit more expressive than C#.

I know C# deeply so I know what good looks like and I know how to get agents to write good C#. F# I'm less familiar with, but we had great success with it.