Question

Consider the following Scala code:

    object MainObject {

    def main(args: Array[String]) {

      import Integer.{
        parseInt => atoi
      }

      println(atoi("5")+2);

      println((args map atoi).foldLeft(0)(_ + _));

  }

First println works fine and outputs 7, but the second one, attempting to map array of strings against a function atoi doesn’t work,with error “value atoi is not a member of object java.lang.Integer”

What’s the difference?

Answer 1

This is because it can’t tell which atoi to use. There are two possibilities parseInt(String) and parseInt(String, int). From the REPL:

scala> atoi <console>:7: error: ambiguous reference to overloaded definition, both method parseInt in object Integer of type (x$1: java.lang.String)Int and  method parseInt in object Integer of type (x$1: java.lang.String,x$2: Int)Int match expected type ?
       atoi

You need to say specifically which one to use, this will work:

println((args map ( atoi(_))).foldLeft(0)(_ + _));