OrElse

A simple implementation of the Maybe (Option) monad.

Installation

Add this line to your application's Gemfile:

gem 'or_else'

And then execute:

$ bundle

Or install it yourself as:

$ gem install or_else

Usage

value = Maybe(nil)        # => Nothing
value.empty?              # => true
value.nil?                # => true
value.exists?             # => false
value.map { |v| v }       # => Nothing (Block is ignored)
value.flat_map { |v| Maybe(v) }  # => Nothing (Block is ignored)
value.or_else { 'foo' }   # => 'foo'

value = Maybe('value')    # => <OrElse::Just>
value.empty?              # => false
value.nil?                # => false
value.exists?             # => true
value.map { |v| v }       # => <OrElse::Just> (Block is yielded the bare value and the block is wrapped in a Maybe)
value.flat_map { |v| Maybe(v) }  # => <OrElse::Just> (Block is yielded the bare value)
value.or_else { 'foo' }   # => 'value' (Block is ignored)

Real life example:

comment = Maybe(post.comments.first).or_else { post.comments.build }

Contributing

1. Fork it ( http://github.com/Originate/or_else/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request