A way to modify an internal function checking.

callable_function_es5.js

//
// ES5 IMPLEMENTATION
// 
function applyFilter(binary){
  return function(a,b){
    return binary(a,b);
  }
}
function add(a,b){ return a + b; }
function mult(a,b){ return a * b }

// Examples:
applyFilter(add)(5,1) // -> 6
applyFilter(mult)(5,1) // -> 5

callable_function_es6.js

//
// ES6 IMPLEMENTATION
// 
const applyFilter = (binary) => {
  return (a,b) => {
    return binary(a,b);
  }
}
const add = (a,b) => { return a + b; }
const mult = (a,b) => { return a * b; }

// Examples:
applyFilter(add)(5,1) // -> 6
applyFilter(mult)(5,1) // -> 5