Basic F# forward / backward operators in JS

forward_backward.js

/* jshint esnext: true */

const FORWARD = '|>';
const BACKWARD = '<|';

function _(...args) {  
  return function(value) {
    return args.reduce((val, curr, index) => {      
      switch(curr) {
        case FORWARD: 
           return args[index + 1](val);          

        case BACKWARD: 
          return val(args[index + 1]);

        default: 
          return val;
      }

    }, value);
  };
}

const pipeline = _(
  '|>', map(_(
    '|>', add, '<|', 1
  )),
  '|>', concat, '<|', ['a', 'b', 'c'],
  '|>', join,
  '|>', remove, '<|', (/,/g)
);

const otherPipeline = _(
  '|>', split, '<|', ''
);


const result = pipeline([1, 2, 3]);
const otherResult = otherPipeline(result);

console.log(result);
console.log(otherResult);

function add(num) {
  return function(val) {
    return val + num;
  };
}

function map(fn) {
  return function(arr) {
    return arr.map(fn);
  };
}

function join(arr) {
  return arr.join();
}

function split(str) {
  return function(val) {
    return str.split(val);
  };
}

function concat(one) {
  return function(two) {
    return one.concat(two);
  };
}

function remove(str) {
  return function(reg) {
    return str.replace(reg, '');
  };
}