Xah Talk Show 2019-09-08 functional programing explained with JavaScript. composition, closure, currying, etc

topics covered:

• explain functional programing in JavaScript
• JavaScript is based on scheme lisp and a language called Self.
• Douglas Crockford, who invented JSON and wrote JavaScript the Good Parts. He popularized functional programing in JavaScript in 2008
• JS: Functional Programing
• JS: Arrow Function
• if you like functional programing, then, in JavaScript, ALWAYS use arrow function. Never with keyword “function” or “class”. Never OOP.
• function taking function as argument
• function return a function
• example of function composition
• Currying is decomposing function that has multiple parameter, into a sequence of functions each with only 1 parameter.
• example of currying. What is Currying in Computer Science?
• example of closure. What is Closure in Programing Language
• closure and clojure.
• real world most common example of function taking a function, is in map and forEach.

// currying in JavaScript

// this is a function that takes 2 args
const ff = ((x,y) => x+y);

console.log ( ff(3,4) === 7 );

const f1 = ((f) => ((y) => f(y)));
const f2 = ((x) => ((y) => y+x) );

let x = 3;
let y = 9917;

console.log ( f1(f2(x))(y) === ff(x,y) );

• xah_talk_show_2019-09-08.txt