Factor out Maybe.of

[christiantakle]

Would I be crazy if I update alle the guides examples to use => syntax? I feel it would make the examples more clear by removing noise.

If you wouldn't mind that change let me know if you prefer a particular style. I would properly make a PR for a chapter and then we could discuss it further.

//  withdraw :: Number -> Account -> Maybe(Account)
var withdraw = curry((amount, {balance}) =>
  Maybe.of(balance >= amount? {balance: balance - amount} : null);

// or
var withdraw = // :: Number -> Account -> Maybe(Account)
  curry((amount, {balance}) =>
    Maybe.of(balance >= amount? {balance: balance - amount} : null);

[KtorZ]

Hey !
Your PR seems to be related to the issue #83.
Nevertheless, we've no news about an existing fork with an ES6 version as discussed. If you want to start one, that would be great :)

[christiantakle]

@KtorZ Cool, I'm starting here #235. Just need guidance on style then I will finish it this weekend.