How can I create a function which accepts a function with specific parameters as an argument?

Question

I'd like to create a function which accepts a function that accepts specific types of parameters as an argument. For example:

myFn(Function paramFn) {
    paramFn([1, 2, 3]);
}

How can I ensure that paramFn accepts a List<int> as an only parameter?

Answer 1

You can use typedef to define the signature you want like described in Kul's answer or you can simply inline the function signature in the parameter:

myFn(void paramFn(List<int> l)) {
  paramFn([1, 2, 3]);
}

Answer 2

You can use typedef to associate a symbol with a function that satisfies the signature you want. Something like

typedef void ParamFn(List<int> l);

myFn(ParamFn f) {
  f('abc');   // compile time error
  f([1,2,3]); // works fine
}