undefined | Better HN

0 pointsdan-robertson5y ago0 comments

Well there is a language that lets you decide how to handle errors separately from the code that actually handles them (eg separating the code that says “please retry” from the code that retries). That language is Common Lisp. But error handling in it is still a pain.

The one advantage it has over most exception systems in my opinion is that the equivalent of try-finally is much more common than try-catch. With exceptions, code often does weird things because it isn’t expecting to lose control flow when an exception is raised, but most languages don’t make it easy to catch stack unwinding a and clean up. In Common Lisp unwind-protect plus the style of with-foo macros tends to make it more common for functions to work when control transfers out of them in abnormal ways.

0 comments

marcus_holmes5y ago

Please stop typing. I don't need another reason to learn LISP! I've been successfully stopping myself from entering that rabbit hole for years in order to prevent yet another "hey I should rewrite all my projects in LISP!". Also looking at you, Rust.

dan-robertsonOP5y ago

Well I was suggesting that the feature doesn’t really turn out that well in CL, so it’s not a great reason. That said, I’ll happily argue that your language should have something like unwind-protect as an easy to use concept before getting something like exceptions.

A big issue with exceptions lately is that they integrate terribly with async style code because they can’t simply unwind past where a promise was created and a promise can be raised to multiple times. The other issue is that they are so pervasively nonlocal that typical code can’t know what might be raised (or what restarts might be available)

marcus_holmes5y ago

I agree. I've been implementing the Event Stream architecture recently in Go and dealing within unwinding errors is a pain in the arse. Do I just repeat the event and hope it works next time? Is there something wrong with the event that means it'll never work? Do I restart the database server because that's what's wrong?

There's this saying that the AA has: "wherever you go, there you are". It's about "doing a geographic" - thinking that moving city/country/continent will change your circumstances and therefore change you. It's false, because no matter where we move we're still the same person so we'll still face the same problems. Wherever we go, there we are.

I think programmers have the same dynamic - if I change my language, I won't make the same errors as I'm making here. Somehow this new language will make me a better programmer because x or y.

I find this difficult to resist. But I also realise its falsehood - I will not be a better programmer in Rust or Lisp than I am in Go. In fact, I have a much better chance of being a better programmer if I drill down in Go and unlearn some problems and relearn some patterns and generally stop learning syntax and start learning deep shit.

Go has a convention on error handling. It may not be ideal. But it's there for a reason, and while we can argue with the reason, it's a valid reason. As a Go programmer, I can fight it and basically reject the language, or I can adopt it and get deeper. I choose that.

But that doesn't mean I don't dream of how much better my life would be if I chose Rust or LISP instead. And yes, I know that all languages have their problems, and a year after learning LISP I wouldn't be writing some infuriated blog post on how EMACS does this weird shit that takes 30s to resolve on a remote server. But don't we all dream of that promised land?

j / k navigate · click thread line to collapse

0 pointsdan-robertson5y ago0 comments

0 comments

marcus_holmes5y ago

dan-robertsonOP5y ago

marcus_holmes5y ago

I think programmers have the same dynamic - if I change my language, I won't make the same errors as I'm making here. Somehow this new language will make me a better programmer because x or y.

j / k navigate · click thread line to collapse