How do you create scala anonymous function with multiple implicit parameters

Question

I have scala functions called "run1" and "run2" which accept 3 parameters. When I apply them I want to provide an anonymous function with implicit parameters. It doesn't work in both cases in example codes below. I want to know if

Is that even possible?
If it is possible, what's the syntax?




       object Main extends App {
          type fType = (Object, String, Long) => Object

          def run1( f: fType ) {
            f( new Object, "Second Param", 3)
          }

          run1 { implicit (p1, p2, p3) => // fails
            println(p1)
            println(p2)
            println(p3)
            new Object()
          }

          def run2( f: fType ) {
            val fC = f.curried
            fC(new Object)("Second Param")(3)
          }

          run2 { implicit p1 => implicit p2 => implicit p3 => // fails
            println(p1)
            println(p2)
            println(p3)
            new Object()
          }
        }

possible duplicate of Function literal with multiple implicit arguments — Noah
– Noah, Commented Jul 18, 2013 at 2:46
It doesn't work in my case at "run2", I'm using scala 2.10.0. — Michael
– Michael, Commented Jul 18, 2013 at 2:57
Your type isn't curried, you're currying it in the run2 function itself. fType = Object => String => Long => Object would work. — Noah
– Noah, Commented Jul 18, 2013 at 2:58
But run2 doesn't take a curried function, which you're trying to give it. — Noah
– Noah, Commented Jul 18, 2013 at 3:01

Noah · Accepted Answer · 2013-07-18 03:00:21Z

17

You're currying the function inside run2 so run2 still needs a non-curried function. See the code below for a version that works:

object Main extends App {
  type fType = (Object, String, Long) => Object
  type fType2 = Object => String => Long => Object //curried

  def run1( f: fType ) {
    f( new Object, "Second Param", 3)
  }

  // Won't work, language spec doesn't allow it
  run1 { implicit (p1, p2, p3) => 
    println(p1)
    println(p2)
    println(p3)
    new Object()
  }

  def run2( f: fType2 ) {
    f(new Object)("Second Param")(3)
  }

  run2 { implicit p1 => implicit p2 => implicit p3 =>
    println(p1)
    println(p2)
    println(p3)
    new Object()
  }
}

edited Jul 18, 2013 at 3:00

answered Jul 18, 2013 at 2:36

Noah

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