What counts as a project in your case? Would you oppose the idea of modules within a project mixing languages? I believe curl is over 500,000 lines of code so in the case of forks a progressive rewrite, module by module seems a lot more achievable than porting everything all at once
I view even the Linux kernel as a project in this sense, as I equally don't like the idea of mixing in Rust modules into the Linux kernel which was so far (and in my opinion should still remain) a C-only codebase.
I'm ok with writing an OS in Rust, but make a separate new project based on Rust, don't mix Rust into an already established project like the Linux kernel.
