scala> val x: boolean = true
x: boolean = true

scala> x.asInstanceOf[java.lang.Object]
unnamed5: java.lang.Object = true

scala> val y: double = 1.0
y: double = 1.0

scala> y.asInstanceOf[java.lang.Object]
unnamed6: java.lang.Object = 1.0

scala>> val x: boolean = true
A>x: boolean = true

scala>> x.asInstanceOf[java.lang.Object]
A>unnamed5: java.lang.Object = true

scala>> val y: double = 1.0
A>y: double = 1.0

scala>> y.asInstanceOf[java.lang.Object]
A>unnamed6: java.lang.Object = 1.0
A>

import java.sql._;
class DataBase
 {
   ....
   def executeFor[A](_sql: String): A =
    {
     ......
     A macth
      {
       case ..... => r.getString(1).asInstanceOf[A];
       case ..... => r.getInt(1).asInstanceOf[A];
      };
     ......
    }
   ....
 };

object pm4 extends Application {
  
  class ResultSet {
     def getInt(col: int): int = 1
     def getDouble(col: int): double = 1.0
     def getString(col: int): String = "Hello"
     def value[A](col: int)(implicit f: (ResultSet, int) => A): A = f(this, col)  
  }
  
  implicit def viewRsToInt(rs: ResultSet, col: int): int = rs.getInt(col)
  implicit def viewRsToDouble(rs: ResultSet, col: int): double = rs.getDouble(col)
  implicit def viewRsToString(rs: ResultSet, col: int): String = rs.getString(col)
  
  val rs = new ResultSet
  
  // Указываем чего точно хочем
  val i =  rs.value[int](1)
  println(i);
  val s = rs.value[String](2)
  println(s);

  // через абстрактный тип T  
  type T = double
  val t = rs.value[T](3)
  println(t)

}

$ scalac -d target pm4.scala
$ scala -cp target pm4                    
1
Hello
1.0

select (
  "age" is smallint,
  "name" is clob,
  "salary" is int )
from ("persons" naturalJoin "employees")
where (
  "gender" == "M" and
  ("city" == "lausanne" or "city" == "geneva"))
orderBy "age"

scala> class U(val v: int) {}
scala> val m=new U(1)
m: U = U@5a936b
scala> m match { case l: U => println("" + l + " " + m) }
line6$object$$iw$$iw$U@5a936b line6$object$$iw$$iw$U@5a936b

object test {
  class A {
    def myMethod() = println("hello")
    def myAnotherMethod() = println("hello")
  }
  
  class B(a: A) {
    def myTest() = (1 :: 2 :: Nil) map (_ + 1)
    def mySuper() = a.myAnotherMethod _
  }
}

target
|-- test$.class
|-- test$A.class
|-- test$B$$anonfun$0.class
|-- test$B$$anonfun$1.class
|-- test$B.class
`-- test.class

$ javap test\$A
Compiled from "methods.scala"
public class test$A extends java.lang.Object implements scala.ScalaObject{
    public test$A();
    public void myAnotherMethod();
    public void myMethod();
    public int $tag();
}

$ javap test\$B
Compiled from "methods.scala"
public class test$B extends java.lang.Object implements scala.ScalaObject{
    public final test$A test$B$$a;
    public test$B(test$A);
    public scala.Function0 mySuper();
    public scala.List myTest();
    public int $tag();
}

$ javap test\$B\$\$anonfun\$0
Compiled from "methods.scala"
public final class test$B$$anonfun$0 extends java.lang.Object implements scala.Function1,scala.ScalaObject,java.io.Serializable{
    public test$B $outer;
    public test$B$$anonfun$0(test$B);
    public final java.lang.Object apply(java.lang.Object);
    public test$B test$B$$anonfun$$$outer();
    public final int apply(int);
    public int $tag();
    public scala.Function1 andThen(scala.Function1);
    public scala.Function1 compose(scala.Function1);
    public java.lang.String toString();
}