There is one particular issue in scala which bites me every time. and each time it bites me ... it bites very hard...
why does this line compile
val x = "10" if (x != 10) { print("do something") } This line compiles and executes but for a "typesafe" language like scala ... this line should result in an compile error
Because the ancestor of all types is Any, and Any defines method !=. See http://www.scala-lang.org/api/current/index.html#scala.Any
So the compiler bends backwards to make your code compile, and goes up the type hierarchy of String("10") until it finds an implementation of != that takes an integer
Pattern matching gives you a bit more help.
scala> val i = 17 i: Int = 17 scala> "42" match { case `i` => } <console>:13: error: type mismatch; found : Int required: String "42" match { case `i` => } ^ scala> case class C(i: Int) defined class C scala> 42 match { case C(_) => } <console>:14: error: constructor cannot be instantiated to expected type; found : C required: Int 42 match { case C(_) => } ^ 
===operator to get what you want. stackoverflow.com/a/30243825/408047610does not equal to"10", so the result you are getting is correct. Why do you think it should be impossible to compare objects of different types?==is simply a method, not an operator, how would you do it differently?