Mostly adequate guide experiments

io.js

var R = require('ramda');
var log = console.log;

var Maybe = function(val) {
  this.__val = val;
}

Maybe.of = (val) => new Maybe(val);

Maybe.prototype.map = function(fn) {
  if (this.__val === undefined) {
    return this;
  } else {
    return Maybe.of(fn(this.__val));
  }
}

var IO = function(fn) {
  this.__val = fn;
};

IO.of = (val) => new IO(val);

IO.prototype.map = function (fn) {
  return IO.of(R.compose(fn, this.__val));
};

var map = R.curry((fn, functor) => functor.map(fn))

var dateIO = IO.of(() => Date.now());
var date = dateIO.map((d) => new Date(d)).map((d) => d.toString()).map(R.take(3))
log(date.__val());

var url = IO.of(() => "http://foo.com?bar=123&baz=999");

// toPairs :: String -> [[String]]
var toPairs = R.compose(R.map(R.split('=')), R.split('&'));

// params :: String -> [[String]]
var params = R.compose(toPairs, R.last, R.split('?'));

// getQueryVal :: Maybe [[String]] -> Maybe String
var getQueryVal = map(R.compose(R.last, R.head));

// findParam :: String -> IO Maybe [String]
var findParam = function(key) {
  return map(R.compose(getQueryVal, Maybe.of, R.filter(R.compose(R.equals(key), R.head)), params), url);
}

log(findParam('baz').__val());  // 999