Sum Types

example.rb

require 'rdl'
extend RDL::Annotate

x = [1,2,3,6]

class Maybe
  attr_accessor :data
end

class Just < Maybe
  def initialize(data)
    @data = data
  end
end

class Empty < Maybe

end

type '(Array) -> Maybe'
def numeros_pares(data)
   x = []
    data.each do |a|
      x.push(a) if a%2 == 0 
    end
    
    if x.count == 0
      return Empty.new
    end
     
    return Just.new(x)
end

puts '==============='
puts 'Returns Just'
result = numeros_pares(x)
puts result.class
puts result.data

puts '==============='
puts 'Returns Empty'
x = [1,3,7]

result2 = numeros_pares(x)
puts result2.class
puts result2.data