Compute-intensive cross-platform library, which language?

[kenarsa]

Suppose you were going to create a compute-intensive cross-platform library in 2024. What would you use? C, C++, Rust, or something else?

[Bostonian]

If the domain is scientific computing, consider Fortran, for which compilers are available on most platforms.

[pklausler]

It depends how portable they want their code to be across implementations and over time. Fortran compilers vary widely in their interpretations of the language, more so than mainstream C/C++ compilers do.