Unequivocally, C. Futhark is clearly meant for reasonably high performance computing and I don't know of a single person in that domain that isn't a competent C

Unequivocally, C. Futhark is clearly meant for reasonably high performance computing and I don't know of a single person in that domain that isn't a competent C programmer even if they spend a lot of time writing code in other languages (C++ mostly, also Fortran, Julia, Python with Cython/Numba, etc.). Functional programming, on the other hand, is something many (most, I'd contend) people in this domain consciously stay away from, myself included.