[whoke]

I like the concept of "inevitable grittiness"! I think languages like Lean actually do a very nice job of pushing the grittiness out to the boundaries of your program. Everything else can stay pure, and in domains that are amenable to mathematical reasoning (compilers, DSP, etc) it feels like a natural fit. I don't think you have to go all in, either. I ported the compiler project I'm working on from TypeScript to Lean and recently spent a weekend making all the functions total and implementing a few basic theorems. On a basic level it feels like writing Haskell, but there's a lot more room to grow with it.