imperial-functional-javascript-talk.js

// @fmsf303 <-- will send the gist later
// Cool stuff:
// Youtube: -> The Role of a Forward Deployed Software Engineer

// function sum(a, b) {
//   return a + b;
// }

const sum = (a, b) => a + b;
const not = (v) => !v;
const isEven = (num) => num % 2 == 0;

// console.log(sum(2,3));
// const double = (num) => num * 2;
// const double = (num) => sum(num, num);

const twice = (fn) => (num) => fn(num, num);
const double = twice(sum);
console.log(twice(sum)(3));
console.log(double(7));

// const isOdd = (num) =>  num % 2 != 0;
// const isOdd = (num) => !isEven(num);
// const isOdd = (num) => not(isEven(num));

const chain = (fn1) => (fn2) => (value) => fn1(fn2(value));

const isOdd = chain(not)(isEven);
console.log(" --> " + isOdd(7));
// chain(not)(isEven)(8);

// data --> {
//   firstName: "maria",
//   lastName: "silva"
// }
//$.get("/getUser/" + username, 
//      (data) => setPageTitle(data.firstName + " " + lastName));

// userOperations.js
const getFullName = (user) => user.firstName + " " + user.lastName;

// $.get("/getUser/" + username, (data) => setPageTitle(getFullName(data)));

// $.get("/getUser/" + username, chain(setPageTitle)(getFullName));

// currying
const sum2 = (a) => (b) => a + b;
console.log(sum2(7)(5));


let indexes = [1,2,3]; // [1001, 1002, 1003]
// 1000
const add1000 = sum2(1000);

console.log(indexes.map(sum2(1000)));

// if( user.name!=null && user.name.length!=0 && (user.address == null && ( is... );

boolean isUserValid(user) => name!=null && name.length!=0 && (user.address == null && ( is... );

...
  if(userIsValid(user))                                                         
...

const userArray = [allusers...];
userArray.filter(userIsValid)

usually twice is to apply the function twice

const twice = (fn) => (num) => fn(num, num);

classically it should be:

const twice = fn => num => fn(fn(num));

then use partial application to get the sum2(3) -> add3 and then twice that... probably.