I'm pretty new to Scala and I want to add a function to a list. I have the following:
var l2: List[() => Unit] = List() def foo() { println("In foo") } And now I want to add a method to the list.
() => println("x") :: l2 It compiles but it doesn't work at runtime.
Next question: Why doesn't the following compile?
l2 = foo :: l2 Thanks.
this is not a correct syntax
() => println("x") :: l2 the correct one is
(() => println("x")) :: l2 and why l2 = foo :: l2 does not compile is because the type of foo does not compliant with l2 to understand it deeply try following
foo.toString however followings will be compiled
var fn = {() => println("y")} l2 = fn :: l2 or
foo _ :: l2 
() => println("x") :: l2 is correct syntax, but interpreted as () => (println("x") :: l2)
foo.toString does not return the type of (or information about) foo, but calls foo and returns the result (The unit-value () in this case).First of all, () => println("x") :: l2 is interpreted as () => (println("x") :: l2). That is a function that takes no arguments and returns a List[Any] (after type inference).
As @dursun states, you want to write:
(() => println("x")) :: l2 Further, l2 = foo :: l2 does not compile because Scala wants you to state explicitly, if you use a function value rather than apply it (basically to protect the programmer from misuse). Use:
foo _ :: l2
l2 = (foo) :: l2compile?