4 ms·

The Clojure Error Message Catalog: common error messages and their meanings

90 points by kimi 10y ago

defenestration 10y ago
When I was learning Clojure a year ago, I spent quite some time Googling the cryptic error messages. An overview like this would have been useful. But I never really understood why Clojure couldn't give better error-messages by itself.
- StreamBright 10y ago
  Yes, I think error messages are the weakest point of Clojure. The rest is pretty good though. :)
  - defenestration 10y ago
    I don't use Clojure regularly now, but learning functional programming with it was great. Tip for starting clojurians: try solving the interactive problems at 4clojure.com.
- kimi 10y ago
  Agreed. But having one place to check before reaching for StackOverflow is nice. The other thing that I find interesting is that when I'm hitting into an error I want it to go away ASAP. But if I read a collected list, an error I don't understand immediately gets my attention. So I think it's an nice way to learn something.
- JamesLeonis 10y ago
  They are working on this right now. There's tons of work done to integrate core.spec into the core functions so they spit out legible error messages instead of raw stack traces and exceptions.
throwaway7645 10y ago
Any chance this or something else could make it into core so that the user doesn't have to go through hoops? Having to add a library to get that is just very...perl lol.
- nickik 10y ago
  With clojure 1.9 clojure.spec will be available and core libraries should be updated. This should make error messages much better. This library however could be a useful edition when you encounter the lower level errors.
  - jgalt212 10y ago
    right b/c you can't clojure.spec everything.
    - preek 10y ago
      Because some of Clojure Core is written in Java or is there another reason that I'm missing?
      - didibus 10y ago
        Some things in Clojure are so dynamic, that it's still an open research problem as to how you can properly assign types to them.
      - jgalt212 10y ago
        because clojure.spec, in practice, only governs interaces. It's not going to help you with bugs that are as a result of data structures generated and manipulated inside of a function.
  - harperlee 10y ago
    Is there any date on when 1.9 will be released? I searched a little bit for the date but couldn't find anything concrete (I know I can access lambdas and that there is a spec "antishim"[1] for 1.8 - I'm just curious). [1] https://github.com/tonsky/clojure-future-spec https://github.com/tonsky/clojure-future-spec
    - JamesLeonis 10y ago
      There is no release date as of yet [1]. But in that thread Sean Cornfield: > Obligatory: “we’ve been running the 1.9 Alphas in production for months so that we can leverage clojure.spec” – no problems so far. [1]: https://groups.google.com/forum/#!topic/clojure/i7ipoze2jos https://groups.google.com/forum/#!topic/clojure/i7ipoze2jos
jgalt212 10y ago
I have not use this package, but looks to be pretty helpful with figuring out stack traces. https://github.com/mmcgrana/clj-stacktrace https://github.com/mmcgrana/clj-stacktrace

90 points by kimi 10y ago

When I was learning Clojure a year ago, I spent quite some time Googling the cryptic error messages. An overview like this would have been useful. But I never really understood why Clojure couldn't give better error-messages by itself.

StreamBright 10y ago
Yes, I think error messages are the weakest point of Clojure. The rest is pretty good though. :)
- defenestration 10y ago
  I don't use Clojure regularly now, but learning functional programming with it was great. Tip for starting clojurians: try solving the interactive problems at 4clojure.com.
kimi 10y ago
Agreed. But having one place to check before reaching for StackOverflow is nice. The other thing that I find interesting is that when I'm hitting into an error I want it to go away ASAP. But if I read a collected list, an error I don't understand immediately gets my attention. So I think it's an nice way to learn something.
JamesLeonis 10y ago
They are working on this right now. There's tons of work done to integrate core.spec into the core functions so they spit out legible error messages instead of raw stack traces and exceptions.

throwaway7645 10y ago

Any chance this or something else could make it into core so that the user doesn't have to go through hoops? Having to add a library to get that is just very...perl lol.

nickik 10y ago
With clojure 1.9 clojure.spec will be available and core libraries should be updated. This should make error messages much better. This library however could be a useful edition when you encounter the lower level errors.
- jgalt212 10y ago
  right b/c you can't clojure.spec everything.
  - preek 10y ago
    Because some of Clojure Core is written in Java or is there another reason that I'm missing?
    - didibus 10y ago
      Some things in Clojure are so dynamic, that it's still an open research problem as to how you can properly assign types to them.
    - jgalt212 10y ago
      because clojure.spec, in practice, only governs interaces. It's not going to help you with bugs that are as a result of data structures generated and manipulated inside of a function.
- harperlee 10y ago
  Is there any date on when 1.9 will be released? I searched a little bit for the date but couldn't find anything concrete (I know I can access lambdas and that there is a spec "antishim"[1] for 1.8 - I'm just curious). [1] https://github.com/tonsky/clojure-future-spec https://github.com/tonsky/clojure-future-spec
  - JamesLeonis 10y ago
    There is no release date as of yet [1]. But in that thread Sean Cornfield: > Obligatory: “we’ve been running the 1.9 Alphas in production for months so that we can leverage clojure.spec” – no problems so far. [1]: https://groups.google.com/forum/#!topic/clojure/i7ipoze2jos https://groups.google.com/forum/#!topic/clojure/i7ipoze2jos

jgalt212 10y ago

I have not use this package, but looks to be pretty helpful with figuring out stack traces. https://github.com/mmcgrana/clj-stacktrace https://github.com/mmcgrana/clj-stacktrace