Pureconfig errors are misleading in the face of ConfigConverts missing.

Today if you have nested configs like the following

case class Foo(bar: Bar)
case class Bar(nel: NonEmptyList[String])

When you try and load a config for Foo you get an error like this: could not find implicit value for parameter conv: pureconfig.ConfigConvert[Foo] when in reality, it’s Bar that’s the problem.

Do you have any ideas about how we could improve the error? One thought I had was to add a “semi automatic” derivation mode where we could create a ConfigConvert on the companion object of each of the nested objects.

Like this:

case class Bar(nel: NonEmptyList[String])

object Bar {
  implicit val configConvert = pureconfig.derive[Bar]
}

case class Foo(bar:Bar)

object Foo{
  implicit val configConvert = pureconfig.derive[Foo]
}

Obviously this changes the way that pureconfig works and we’d have to have 2 different imports, one for “full auto” and one for “semi auto” derivation.

@melrief, Would you be interested in a change like this? Do you see another way around the terrible error messages?

Thanks!

[ruippeixotog]

Closed by #279.

[melrief]

@francisdb thanks for the links, I’ll have a look at the code. I think we could change the codec generator from the one that we have shapeless based to a custom macro based one. I’m not happy to have my own macro but if it makes much cleaner the error messages then I’m for trying it. I’ll talk with the other two authors and see how we want to proceed.