The large monoliths with huge ecosystems almost never get rewritten in anything. They stick around as legacy systems where the programming language & much of it

The large monoliths with huge ecosystems almost never get rewritten in anything. They stick around as legacy systems where the programming language & much of its code are preserved over time. Any discussion about rewriting such a thing entirely in a different, safer language would be foolish based on empirical evidence that it won't happen. I know this. It's why you see me on INFOSEC end suggesting to (a) gradually rewrite it in a safer version of C, (b) use compiler tech that automatically ads safety, (c) use monitoring tech or CPU's that spot severe problems, and/or (d) virtualize it as a deprivileged VM on top of something better. You won't see me tell them to rewrite it in Ada, D, or Rust because they'll never do it no matter what I say. Whereas, suggesting a rewrite can lead to results when the tool is new, small with significant use + bugs, or small to medium with safety- or security-critical usage. Examples of last ones include DNS, web, key, file, and other servers that are mission critical and widely deployed. Example rewrites that actually happened... we'll go with DNS... are IRONSIDES DNS in SPARK Ada and bluejekyll's TrustDNS in Rust. Maybe add Lobo web browser since it ambitiously wrote a browser in pure Java. Dead now but impressive how far project got. So, yeah, there's certainly pointless discussion that waste space on HN. Arguing for a Linux rewrite is always one of them unless someone with a pile of money dedicated to rewrites is asking which mainstream OS to rewrite in safer language. I'd prefer FreeBSD but probably recommend Linux for higher impact.