Writing a transpiler is easily the most boring and tedious job you can have, especially if the target or source language is useless (so you don't learn anything useful as a matter of course).

I think it's uniformity. You have 9(n) all over the place, and only pay attention to the number in parentheses. It's more error-prone to count repeating characters, and it's easier (to me) to notice a typo in the form 9(4) instead of 9(3) than 9999 instead of 999.

Just say you worked on an on-prem private cloud.

I’m mid 40s, had mainframe on my resume from probably 15 years in financial services (not the exciting, high paying kind either). I moved into tech in my mid 30s and am now in a fairly senior leadership role. But that person that gave me a shot in tech, at a YC company that pretty much everyone here has heard of, was in their 20s! I tell you this to encourage you to do interesting things, whatever you think those are. You wouldn’t want to work with a founder or manager who dismisses you because your keywords don’t overlap theirs. You want to work with the founder or manager who asks questions and wants to understand what you learned and how that experience helps you now.

Mainframes may not be what you’d work on at a startup today, but they’re complicated pieces of engineering, and writing software for them requires you to understand a lot about how they work. Updating or rewriting their software further requires you to understand how the people before you _thought_ they worked. That’s how I tell that story.

Python has decimals for example as do many other languages. C# decimal is used everywhere currency is used (I really hope). But apart from currency... why would you use base 10? We've got native bigints in lots of languages so you don't even have to care how they're represented internally.

The COBOL syntax for that looks like

    PICTURE IS $-999,999.99

which defines a signed money value represented in decimal. If you print that value, it will be formatted as requested.

There are a few other formatting characters. A "CR" at the end will cause negative numbers to be printed with "CR" (Credit) at the end. A "Z" causes lead zero suppression. "*" causes lead zeros to be replaced with asterisks, for check-writing. Numeric display formatting is an attribute of the data.

That concept, and built-in support of money-like values, has been lost in later languages. In Rust you can have implicit Display or Debug functions for types, although it's mostly used for debugging.

That exists. There are multiple vendors that have solutions to automatically transform COBOL code.

Deloitte, for example, has quite a big practice around Mainframe modernization with a toolsuite https://www2.deloitte.com/us/en/pages/consulting/topics/appl...

And AWS bought a company with such a toolsuite and offers it now as a service https://aws.amazon.com/de/mainframe-modernization/capabiliti...

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