v1.3.0

v1.3.0 2019-08-03

BREAKING CHANGES

• Support for Ruby 2.3 was dropped.

Added

• Result#either (waiting-for-dev)

  Success(1).either(-> x { x + 1 }, -> x { x + 2 }) # => 2
  Failure(1).either(-> x { x + 1 }, -> x { x + 2 }) # => 3

• Maybe#to_result (SpyMachine + flash-gordon)

  Some(3).to_result(:no_value)   # => Success(3)
  None().to_result { :no_value } # => Failure(:no_value)
  None().to_result               # => Failure()

• Do notation can be used with extend. This simplifies usage in class methods and in other "complicated" cases (gogiel + flash-gordon)

  class CreateUser
    extend Dry::Monads::Do::Mixin
    extend Dry::Monads[:result]
  
    def self.run(params)
      self.call do
        values = bind Validator.validate(params)
        user = bind UserRepository.create(values)
  
        Success(user)
      end
    end
  end

  Or you can bind values directly:

  ma = Dry::Monads.Success(1)
  mb = Dry::Monads.Success(2)
  
  Dry::Monads::Do.() do
    a = Dry::Monads::Do.bind(ma)
    b = Dry::Monads::Do.bind(mb)
    
    Dry::Monads.Success(a + b)
  end

• {Some,Success,Failure}#[] shortcuts for building arrays wrapped within monadic value (flash-gordon)

  Success[1, 2] # => Success([1, 2]) 

• List.unfold yields a block returning Maybe<Any>. If the block returns Some(a) a is appended to the output list. Returning None halts the unfloding (flash-gordon)

  List.unfold(0) do |x|
    if x > 5
      None()
    else
      Some[x + 1, 2**x]
    end
  end # => List[1, 2, 3, 4, 5]

• Experimental support for pattern matching! 🎉 (flash-gordon)

  case value
  in Failure(_) then :failure
  in Success(10) then :ten
  in Success(100..500 => code) then code
  in Success() then :empty
  in Success(:code, x) then x
  in Success[:status, x] then x
  in Success({ status: x }) then x
  in Success({ code: 200..300 => x }) then x
  end

  Read more about pattern matching in Ruby:

  • https://medium.com/@baweaver/ruby-2-7-pattern-matching-destructuring-on-point-90f56aaf7b4e
  • https://bugs.ruby-lang.org/issues/14912

  Keep in mind this feature is experimental and can be changed by 2.7 release. But it rocks already!

Compare v1.2.0...v1.3.0