Warn on incorrent keyword/named arguments with flycheck

[sarna]

What do you think about warning the user about calls like these?

(defn named [&named arg] # I used &named here but same goes for &keys
  (print arg))

(named :arg "hi") # correct
(named :arrgh "this will not print") # wrong

I can't think of any case when the user would want this, and it should be detectable before running the code.

Splicing would be out of scope of this issue (e.g. (named ;(kvs options))).

For more context - Zulip thread. I originally opened this issue in the janet-lsp project, but seems like this would be a better place for it.

[bakpakin]

This would be nice to have, but it's not clear if moving this check to the compiler or flychecker would be better. Putting it in the compiler would catch more cases, since not everyone uses the flychecker, but it would invalidate some currently correct programs.

I can't think of any case when the user would want this, and it should be detectable before running the code.

Here is a contrived situation:

(defn func-1 [&named a b] (print a ", " b))
(defn func-2 [&named a c] (print a ", " c))

(def func (if (> 0.5 (math/random)) func-1 func-2))
(func :a 1 :b 2 :c 3)

Of course, most programs like this could be trivially rewritten, but duck typing function signatures allows for flexibility in design without need lots of redundant parameters.

[sarna]

Interesting, I didn't think of that. The example looks a bit funny, but I can imagine someone using that in the real world to handle cases with different OSs or similar.

This would be nice to have, but it's not clear if moving this check to the compiler or flychecker would be better. Putting it in the compiler would catch more cases, since not everyone uses the flychecker, but it would invalidate some currently correct programs.

I think it would be better in the flychecker, preferably with an easy way of marking it as intentional if it's so. Compiler warnings tend to get really cumbersome for the user. But it's not a strong opinion, you have more experience & better understanding here :)