Macro expansion error with generic Inference #454
Comments
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That's interesting! I've never worked with an explicit Unfortunately the instance scala> implicitly[Greater[_5] ==> Greater[_10]]
res1: Greater[_5] ==> Greater[_10] = Inference(false,greaterInferenceNat(5, 10))Which shows that we can find an I think what is missing to define your def infer(tp: F[T, B])(implicit rt: RefType[F], I: B ==> A): Option[F[T, A]] =
if (I.isValid) Some(rt.unsafeRewrap[T, B, A](tp)) else NoneWith def convert[B, A](value: String)(implicit I: B ==> A,
V: Validate[String,B]): Either[String, String Refined A] = {
val res = applyRef[String Refined B](value)
res.flatMap(v => infer(v).fold(Left("B does not implies A"))(Right.apply) )
} |
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Thanks. That is useful. You are right, an It would be cool to have a subtype of Inference which is always valid ( Something like that: sealed trait Inference {
def isValid: Boolean
def show: String
}
object Inference {
object ValidAlways extends Inference {
def isValid: Boolean = true
}
object ValidNever extends Inference {
def isValid: Boolean = false
}
final case class ValidWhen(isValid: Boolean) extends Inference
}
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Fixes fthomas#454 Here I've tried to have Inference as a trait and added 2 subtypes - InferAlways - InferWhen With that we can directly have a safe conversion whenever an InferAlways is presen
I have the following generic method to convert from
StringtoString Refined A.However, this is somewhat different because I'm going to try to convert String to
String Refined Band then infer A from B, as follows:I need a
Validate[String,B]to convert from String toString Refined Band I need aInference[B,A]to convert fromString Refined BtoString Refined A. So far so good.But this code does not compile. This is the stacktrace:
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