There are millions and millions of lines of old COBOL code. I’m surprised there isn’t a commercial “pluggable” transpiler product. Read in COBOL, output Java, Rust, Go… Many COBOL systems also have a lot of intelligence in the job stream order, and dependencies - so that needs to be converted too. This seems like a no-brainer to build a consulting practice and tools around. Oh, and the data has to be converted too.
gnu-cobol is likely what you're after (cloudflare even used it to demo their Worker platform) but my experience has been that the language isn't the nonsense it's the environmental that's horrific to port
Consider a hypothetical Python example:
import os
os.system("DIRECTORY ./SHELVED_STATE")
if you ported the python to C# it wouldn't suddenly work on Windows or Linux
Mainframe OSs are fun to learn precisely because they are profoundly alien to users of modern computers. You don’t even need to go the mainframe route - installing OpenVMS on an x86 machine already gives you an environment full of mysteries to be explored.
