A Ruby port of Scala's Option monad. Tries to be faithful but also pragmatic in RE: to duck typing.
Blog post: http://robares.com/2012/09/16/ruby-port-of-scala-option/
Add this line to your application's Gemfile:
gem 'option'
And then execute:
$ bundle
Or install it yourself as:
$ gem install option
Generally, you want to use the Option(A) wrapper method to box your value. This will make the right decision as to what your initial value should be:
foo = Option("bar")This will allow you to now manipulate the value in the box via various means:
# get the value
foo.get #=> "bar"
# return a default if the box is None
None.get_or_else { "default" } #=> "default"
# map the value to another option
foo.map { |v| v.upcase } #=> Some("BAR")
# does the value meet a requirement?
foo.exists? { |v| v == "bar" } #=> true
# return the value or nil depending on the state
foo.or_nil #=> "bar"
# chain values
foo.map { |v| v * 2 }.map { |v| v.upcase }.get_or_else { "missing" } #=> BARBAR
# attempt to extract a value but default if None
None.fold(-> { "missing" }) { |v| v.upcase } #=> missing
# filter values returning an option
foo.filter { |v| v == "baz" } #=> None
# Side-effects
foo.inside { |v| v.upcase! } #=> Some("BAR")
# use in a for loop
for value in foo
puts value #=> bar
end
- Fork it
- Create your feature branch (
git checkout -b my-new-feature) - Implement your feature. Patches not considered without accompanying tests.
- Commit your changes (
git commit -am 'Added some feature') - Push to the branch (
git push origin my-new-feature) - Create new Pull Request