Confused about javascript function returning multiple functions with many fat arrow

问题

I have problem with my cs homework. I need to access the x value of the function, but my codes is returning me an empty function instead of with the values

I have googled all the currying and closures, but none of them are advanced enough to help me solve my problem

const pair = (x, y) => f => f(x, y);  // Do not edit this function
const head = p => //Answer here                

console.log(head(pair(1,2)))          // Do not edit this

my console keeps returning me functions instead when I try all the combinations

function(a,b){return a;}

回答1:

You could change head function like this:

const pair = (x, y) => f => f(x, y); 
const head = f => f(a => a)

console.log(head(pair(1,2)))

回答2:

my console keeps returning me this instead

function(a,b){return a;}

Let's make this easier to read. In ES5, your code looks like this:

var pair = function(x, y) {
  return function(f) {
    return f(x, y);
  }
};

var head = function(p) {
  return function(a, b) {
    return a;
  }
};

You need to pass the function returned from head to the function returned by pair(1, 2). So you need to swap which order you're calling the functions in:

console.log(pair(1, 2)(head()));

回答3:

Not sure if I understand your question correctly or not but I guess you are trying to do this

const pair = (x, y) => f => f(x, y); 
const head = (x, y) => x;

console.log((pair(1,2)(head)))

if not then this one from above is correct

const pair = (x, y) => f => f(x, y); 
const head = f => f(a => a);

console.log(head(pair(1,2)))

来源：https://stackoverflow.com/questions/57736496/confused-about-javascript-function-returning-multiple-functions-with-many-fat-ar

标签

javascript

function

ecmascript-6

closures

currying