I&#39;m trying to call a `Shapeless` macro from inside a `quasiquote` with `Scala` and I&#39;m not getting what I would like to get. 

My macro doesn&#39;t return any errors but it doesn&#39;t expand `Witness(fieldName)` into `Witness.Lt[String]`

    val implicits = schema.fields.map { field =&gt;
      val fieldName:String = field.name
      val fieldType = TypeName(field.valueType.fullName)
      val in = TermName(&quot;implicitField&quot;+fieldName)
      val tn = TermName(fieldName)
      val cc = TermName(&quot;cc&quot;)
      q&quot;&quot;&quot;implicit val $in = Field.apply[$className,$fieldType](Witness($fieldName), ($cc:   $className) =&gt; $cc.$tn)&quot;&quot;&quot;
    }

Here is my `Field` definition: 

    sealed abstract class Field[CC, FieldName] {
      val  fieldName: String
      type fieldType
    
      // How to extract this field
      def  get(cc : CC) : fieldType
    }
    
    object Field {
      // fieldType is existencial in Field but parametric in Fied.Aux
      // used to explict constraints on fieldType
      type Aux[CC, FieldName, fieldType_] = Field[CC, FieldName] {
        type fieldType = fieldType_
      }
    
      def apply[CC, fieldType_](fieldWitness : Witness.Lt[String], ext : CC =&gt; fieldType_) : Field.Aux[CC, fieldWitness.T, fieldType_] =
        new Field[CC, fieldWitness.T] {
          val fieldName  : String = fieldWitness.value
          type fieldType = fieldType_
          def get(cc : CC) : fieldType = ext(cc)
        }
    }

In this case the implicit I generate looks like:

    implicit val implicitFieldname : Field[MyCaseClass, fieldWitness.`type`#T]{
      override type fieldType = java.lang.String
    }

If it had been defined outside a `quasiquote` it would generate something like: 

    implicit val implicitFieldname : Field.Aux[MyCaseClass, Witness.Lt[String]#T, String] = ...

Is there something that can be done?

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How to use Shapeless in a Quasiquote?