Q:

scala, using class member function as first class functions

I want to assign a member function of a class instance as a first class function to a variable:
class A(val id:Int){ def f(u:Int)=id+u }
val a= new A(0)
val h=a.f         // fails: interpreted as a.f(with missing parameter u)
val h1 = (u:Int)=>a.f(u)    // OK and does what we want

We can get the desired effect by assigning an appropriate anonymous function.
Is this the only way?
I searched but could find no reference at all.

A:

Use a placeholder to indicate it is partially applied:
scala> class A(val id:Int){ def f(u:Int)=id+u }
defined class A

scala> val a = new A(0)
a: A = A@46a7a4cc

scala> val h = a.f _
h: Int => Int = <function1>

scala> h(2)
res0: Int = 2

EDIT
Trying the code out in the REPL prints 
scala> val h = a.f
<console>:9: error: missing arguments for method f in class A;
follow this method with `_' if you want to treat it as a partially applied function
       val h = a.f
                 ^

