Any kind of FP tweaks

composeOverPipe.js

const trace=label=>value=>{
  console.log(`${ label }: ${ value }`);
  return value;
};
const simpleTrace = value => console.log(value);

const pipe = (...fns) => (args) => fns.reduce((arg, fn) => fn(arg), args);
const compose = (...fns) => (args) => fns.reduce((arg, fn) => fn(arg), args);
const mult = a => b => a*b;
const add = (a) => (b) => a+b;
const double = a => a * 2;
const plusThree = a => a + 3;

compose (double, plusThree)(1); //8
compose(plusThree, double)(1)//5
compose (add(2), add(2))(1)//5
compose (plusThree, mult(3), add(1), double)(2)//18
pipe(double, add(1), mult(3), plusThree)(2)//18
pipe(double, trace('step2'), add(1), mult(3), simpleTrace, plusThree)(2)//18

flatArray.js

const notFlattenArray = [1, [2], [[3]], [[[[4]]]]];
const flatt = (a, b=[]) =>  a.reduce((acc,val) =>  Array.isArray(val) ? flatt(val,acc) : [...acc, val] , b);
flatt(notFlattenArray); //[1,2,3,4]

functer.js

//basic functer
class Container {
  constructor(x) {
    this.$value = x;
  }
  
  static of(x) {
    return new Container(x);
  }
}
Container.prototype.map = function (f) {
  return Container.of(f(this.$value));
};
Container.of('flamethrowers').map(s => s.toUpperCase());