scala-expressions-2-type-conversion.scala

scala> "foo" + 4
res0: String = foo4

scala> 4 + "foo"
res1: String = 4foo

scala> 4 + "2.0"
res2: String = 42.0

scala> 2 * "21"
<console>:8: error: overloaded method value * with alternatives:
  (x: Double)Double <and>
  (x: Float)Float <and>
  (x: Long)Long <and>
  (x: Int)Int <and>
  (x: Char)Int <and>
  (x: Short)Int <and>
  (x: Byte)Int
 cannot be applied to (String)
              2 * "21"
                ^
                
scala> // Stuff to come

scala> implicit def string2int(s: String) = s.toInt
string2int: (s: String)Int

scala> 2 * "21"
res3: Int = 42