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Comment by rbanffy | Hacker News Reader

Worth noting even its creators say JCL is the worst language ever invented.

> Worth noting even its creators say JCL is the worst language ever invented.

I don't dispute that, but I'd kinda like to hear the specifics of their reasoning.

I've never actually used JCL, but I'm willing to cut it a little slack because, IIRC, it literally started in the 60s as a way to specify job-execution information on a punched cards for batch processing systems that had as little as 8K of memory. What I've read about very early personal computers with similar amounts of memory makes me think it requires serious compromises to implement anything that actually works on such a system.

Like everything on mainframe, JCL is old and has lots of warts. But it is, essentially, what is known today as "infrastructure as code".

As someone who doesn't know what JCL is, this is an enlightening statement. Anyone that's used IaC oriented languages know they suck too.

> old and has lots of warts

It was still the worst programming language ever created even when it was new and wart free.

Some programs have warts before the first line of code is written.

JCL was not exactly fun to write, but M4 gives it a run for its money.

dnl And the comment syntax is nuts!

I think anything that becomes a right of passage (editing the m4 file for sendmail) has to have a mention when discussing bad implementations.

I had to learn some JCL to do the mastering the mainframe challenge, other than the syntax being really odd, its not awful.

Yeah. JCLs been that way for long time. That's why it's recommended not to keep JCLs very creative. It should be easy for the operator to understand what to do if job fails. Re-run from top or restart from particular step.

If you don't make thing complicated, it's easy.

> That's why it's recommended not to keep JCLs very creative.

That's solid advice for any language. Clever code actually isn't.

I worked with mainframes long ago, for about a year.

When it came to JCL, the advice I got and what everyone I worked with did, was to copy working JCL and modify it. I never wrote it from scratch, nor did I know anyone who did.

Do you have a source for that? I'd like to show it to some mainframe fanboys at work that praise that abomination

Fred Brooks led IBM 360 software development. From his oral history at the Computer History Museum [1] (on p.33 of 49):

That’s the worst mistake we made was JCL.

Yeah. Well the existence of JCL was a mistake. Building it on a card format was a mistake. Building it on assembly language was a mistake. Thinking of it as only six little control cards instead of a language was a mistake so it had no proper sub-routine facilities, no proper branching facilities.

It kind of grew. It kind of grew but when you end up with your data definitions doing all the verbiage things because you’ve limited yourself to six verbs that’s a language mistake.

We didn’t see it as a language was the fundamental problem. We saw it as a set of control cards.

And lo and behold they’re still around, the dusty decks that nobody dare touch because they run and nobody knows what’s inside

Incredibly complicated, the keyword parameters and the set goes on and on and on and on ...

[1] https://archive.computerhistory.org/resources/access/text/20...

This does not sound like they are saying the language itself is bad for the users.

It sounds more like they are saying it’s a nightmare for the creators of the language to maintain.

It sounds to me like they think it's a terrible language for the users because they never put the normal engineering rigor that they would normally for a full new language. It grew 'organically' to it's own (and it's users') detriment.

> And lo and behold they’re still around, the dusty decks that nobody dare touch because they run and nobody knows what’s inside

Any language that allows its users to do that to themselves is a very bad language. Good languages encourage good practices.

I have to say it's the kind of impression I get from Terraform. I get the feeling it evolved from a JSON-like syntax to something that has conditionals, then variables, then some form of iteration, then some form of functions, but they are more like macros because the language is declarative... At every stage it seems it was impossible to step back and think it through.

I challenge them to try out DOORS DXl

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