TableQuery.scala

import scala.quoted._

class Tag

class TableQuery[E](f: Tag => E) {
  override def toString: String =
    s"TableQuery(${f(new Tag)})"
}

object TableQuery {
  def apply[E](f: Tag => E): TableQuery[E] = new TableQuery[E](f)
  
  inline def apply[E]: TableQuery[E] = ${ applyExpr[E] }
  
  def applyExpr[E](implicit qctx: QuoteContext, e: Type[E]): Expr[TableQuery[E]] = {
    import qctx.tasty._
    val eTpe = e.unseal.tpe
    val tagTpe = summon[scala.quoted.Type[Tag]].unseal.tpe
    val mt = MethodType(List("tag"))(_ => List(tagTpe), _ => eTpe)
    val cons = Lambda(mt, { tag =>
      Apply(
        Select.unique(New(TypeIdent(eTpe.typeSymbol)), "<init>"),
        List(tag.head.asInstanceOf[Term])
      )
    })

    '{ TableQuery.apply[E](${ cons.seal.cast[Tag => E] }) }
  }
}