Operations functions have to return a functions

that recieves a number, provides math operation and returns math result

let plus      = (r) => (l) => l + r
let minus     = (r) => (l) => l - r
let times     = (r) => (l) => l * r
let dividedBy = (r) => (l) => l / r

So our num function should recive the operation func or none (undefined)
if f is undefined we have to return a number, or pass the number into function f and get result

//simple realization
(f) => { 
  if(f) {
    return f(num)
  } 
  return num
}
//now we can hide f check in args definition
(f = function(val){ return val }) => f(num)
//and simplify it with arrow function
(f = val => val) => f(num)

ANd we automaticaly declare all nums functions by using this[math] = *function*

'zero one two three four five six seven eight nine'.split(' ').forEach(...)

mth - it's element of array and the name of function ('one', 'two', 'three' etc.)

num - it's a index of array and the numeric value (0, 1, 2, 3 etc.)

(mth, num) => this[mth] = (f = val => val) => f(num) 

Operations functions have to return a functions

that recieves a number, provides math operation and returns math result

let plus      = (r) => (l) => l + r
let minus     = (r) => (l) => l - r
let times     = (r) => (l) => l * r
let dividedBy = (r) => (l) => l / r

So our num function should recive the operation func or none (undefined)
if f is undefined we have to return a number, or pass the number into function f and get result

//simple realization
(f) => { 
  if(f) {
    return f(num)
  } 
  return num
}
//now we can hide f check in args definition
(f = function(val){ return val }) => f(num)
//and simplify it with arrow function
(f = val => val) => f(num)

ANd we automaticaly declare all nums functions by using this[math] = *function*

'zero one two three four five six seven eight nine'.split(' ').forEach(...)

mth - it's element of array and the name of function ('one', 'two', 'three' etc.)

num - it's a index of array and the numeric value (0, 1, 2, 3 etc.)

(mth, num) => this[mth] = (f = val => val) => f(num)