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Nice article. I must say though, I hate dialyzer. Did I get it wired up at my company? Oh yeah. I made it part of our CI pipeline in my first few weeks. My te

Nice article. I must say though, I hate dialyzer. Did I get it wired up at my company? Oh yeah. I made it part of our CI pipeline in my first few weeks. My team and I have liked the help it has given us. But where it falls down is when it’s errors are stupidly obtuse or when it doesn’t catch errors. By construction it is an unsound check: some errant programs will not be caught because Elixir (and Erlang) make it really hard to infer types. The creators wanted something that could check existing Erlang code, [1] so they had to sacrifice soundness for completeness. [2] So often I really want soundness checks, and I have spent many an hour chasing down stupid little type errors that dialyzer doesn’t tell me how to find. So that’s the hate. Overall, though, it does catch a lot of stupid mistakes, so I still appreciate its efforts. :) [1]: Lindahl and Sagonas, “Practical Type Inference Based on Success Typings.” [2]: I have a write up on the difference between some of these terms here: https://lambdaland.org/posts/2022-03-02_sound_complete_and_duals/ https://lambdaland.org/posts/2022-03-02_sound_complete_and_d...

bmitc 4y ago
I was recently having trouble with it on a project I'm working on along with a book. I am still a bit stumped because I couldn't make it fail. I started to get suspicious when I knew a spec was incorrect (I just hadn't updated a type yet), but yet Dialyzer was happy. I even started to worry it wasn't configured properly or there was a state problem, but deleting the `_build` directory didn't help. Still not sure. I've used it successfully in another personal project. Do you know of a good reference that discusses what types of problems Dialyzer is good for and what problems it isn't good for?
- ashton314 4y ago
  Woof. I feel your pain. That paper by Lindahl and Sagonas is pretty decent at exploring some of the theoretical limitations of the system. (DM me on Matrix if you can’t find it: I’m @ashton314:lambdaland.org Email is also in my resume which is on my blog; see bio) Beyond that… er no, unfortunately. I’ve done many a web search trying to figure out some funky behaviour. :-P

bmitc 4y ago

I was recently having trouble with it on a project I'm working on along with a book. I am still a bit stumped because I couldn't make it fail. I started to get suspicious when I knew a spec was incorrect (I just hadn't updated a type yet), but yet Dialyzer was happy. I even started to worry it wasn't configured properly or there was a state problem, but deleting the `_build` directory didn't help. Still not sure. I've used it successfully in another personal project. Do you know of a good reference that discusses what types of problems Dialyzer is good for and what problems it isn't good for?

ashton314 4y ago
Woof. I feel your pain. That paper by Lindahl and Sagonas is pretty decent at exploring some of the theoretical limitations of the system. (DM me on Matrix if you can’t find it: I’m @ashton314:lambdaland.org Email is also in my resume which is on my blog; see bio) Beyond that… er no, unfortunately. I’ve done many a web search trying to figure out some funky behaviour. :-P