Rewrite parseIf

[lulucca12]

Used mfilter :: MonadPlus m => (a -> Bool) -> m a -> m a as Maybe has an automatic instance of MonadPlus derived from the instance of Alternative.

[rexim]

@lulucca12 hey! Thanks for the Pull Request, unfortunately it doesn't add any new functionality to the parser. Please check https://github.com/tsoding/haskell-json#contribution-notes for more information.

[lulucca12]

@rexim I don't see the meaning of this. Isn't what I did the exact same thing as #4 did? Rewrite the implemetation without adding fuctionality and it got merged?
Besides isn't that what managers are for? I remember one time when Linus Torvalds said about his bad actions at the Linux maling list as he invented git the way he did for being able to pass his work to others.
So why don't just elect a manager or be more liberal about it and enable merging without supervision, just reviewing?

[rexim]

@lulucca12 #4 was submitted before e886bfb

[lulucca12]

@rexim does that mean that you changed the rules in the middle of the game?
Fine, thats why it is open source ;)