Exercise 2

  // Exercise 2
// ==========
// Write a validation function that checks for a length > 3. It should return Right(x) if it is greater than 3 and Left("You need > 3") otherwise
console.log("--------Start exercise 2--------")

var ex2 = function(x) {
//   return "TODO: write me";

// **** 1. the solution:
  return (x.length > 3) ? Right(x) : Left("You need > 3")
}


assertDeepEqual(Right("fpguy99"), ex2("fpguy99"))
assertDeepEqual(Left("You need > 3"), ex2("..."))

Above: we just wrote a validation that returns a Right or a Left

  // Exercise 3
// ==========
// Use ex2 above and Either as a functor to save the user if they are valid

var save = function(x){ console.log("SAVED USER!"); return x; }

var ex3 = undefined
// solution
var ex3 = compose(map(save), ex2)

console.log("--------Start exercise 2--------")
assertDeepEqual(Right("fpguy99"), ex3("fpguy99"))
assertDeepEqual(Left("You need > 3"), ex3("duh"))

  // Exercise 4
// ==========
// Get the text from the input and strip the spaces
console.log("--------Start exercise 4--------")

var getValue = function(x){ return document.querySelector(x).value }.toIO()
var stripSpaces = function(s){ return s.replace(/\s+/g, ''); }

var ex4 = undefined
// solution
var ex4 = compose(map(stripSpaces), getValue)

assertEqual("honkeytonk", runIO(ex4('#text')))

What's great is that map is so generic that you can put in any type of container.

This exercise uses IO. Note the in assertEqual you have to run it with runIO(ex4('#text')) because it has an IO in it.