Question

I have the following map extension

object ImplicitMap {
  implicit def extendMap(m : Map[String,Any]) = new MapExtension(m)
}
class MapExtension(m : Map[String,Any]) {
  def +?(conditional:Boolean)(pair:(String,Any)):Map[String,Any] = 
    if (conditional) m + pair
    else m
}

this function, when used gives the compile time error of Boolean does not take parameters, however a written explicit test (as follows) works correctly

 test ("Map +?") {

    def +?(conditional:Boolean)(pair:(String,Any)):Map[String,Any] = if (conditional)   Map.empty + pair else Map.empty

    +?(true)("hi" -> 2) should equal (Map("hi" -> 2))
  }

Answer 1

I assume you are trying to write someMap +? (cond)(pair), but that will not work, as it will be evaluate to someMap.+?(cond(pair)), you have to use it as a normal method, not as an operator. someMap.+?(cond)(pair) works for me.

scala> Map("Foo" -> "bar")
res2: scala.collection.immutable.Map[java.lang.String,java.lang.String] = Map(Foo -> bar)

scala> res2.+?(true)(("foo", "bar"))
res3: Map[String,Any] = Map(Foo -> bar, foo -> bar)

scala> res2 +? (true)(("foo", "bar"))
<console>:13: error: Boolean(true) does not take parameters
              res2 +? (true)(("foo", "bar"))