Spiel

Spiel has helper methods and classes to make your code clean. The main concepts come from Scala and Haskell and other languages which has embraced the functional paradigm in different degrees

It contains very lightweight solutions with no extra dependencies on other gems.

Supports Ruby 1.9.2 and up

Installation

Add this line to your application's Gemfile:

gem 'spiel'

And then execute:

$ bundle

Or install it yourself as:

$ gem install spiel

Usage

Maybe

Ruby's maybe inspired by Haskell's Maybe.

Imagine you want to do know who of your friends boss is richer:

User.find_by_name(name).boss.credit_card(:main).balance(:credit)

But find_by_name, parent, credit_card or balance can be nil, you will get a NoMethodError and your program will die.

You can check for nil on each step:

 user = User.find_by_name(name)
 parent &&= user.parent
 card &&= parent.credit_card(:main)
 balance &&= card.balance(:credit)

But your buggy first version read almost like English and now this looks so much .... like C.

You can also use ActiveSupport and its try method:

 User.find_by_name(name).try(:parent).try(:credit_card, :main).try(:balance, :credit)

That was long! And it kind of repetitive and, what is going on with those double symbols on these methods. Ugly, ugly.

So you try this gem and you get this awesome line:

Maybe(User.find_by_name(name)).parent.credit_card(:main).balance(:credit)

And that's it, this will get you an object that works as balance and the chain will never explote because of some nil on the line.

You can even do

substracted = Maybe(User.find_by_name(name)).parent.credit_card(:main).balance(:credit).get_or_else(0)

Maybe objects has one method only 'get_or_else' it will return the object at that point of your chain or some default you pass as param if the chain got broken

Contributing

Fork it
Do your changes, the specs pass
Send a pull request