Default implicit Success values can lead to unintentional retries

[ncreep]

Hi,
Currently the Success object provides default Success implicits for various standard types:

implicit def either[A,B]: Success[Either[A,B]] =
  Success(_.isRight)
implicit def option[A]: Success[Option[A]] =
  Success(!_.isEmpty)
implicit def tried[A]: Success[Try[A]] =
  Success(_.isSuccess)

These are available even without explicit import. I found that this can lead to unintentional retries when forgetting to add your own implicit Success value.

For example, when querying a database I have a result type of Future[Option[???]], where an empty Option stands for a missing value in the database. In some use cases, this is a legitimate return value, and retrying the query won't change anything.

The correct behavior here would be to explicitly have:

implicit val always = Success.always

in scope.

But if you forget to add this line, everything still compiles and the option implicit from the Success object is picked up, leading to unwanted retries.

I would suggest removing the implicit modifier from defs above to avoid the unintentional retries.

Thanks