v1.2.0

v1.2.0 2019-01-12

BREAKING CHANGES

• Support for Ruby 2.2 was dropped. Ruby 2.2 reached its EOL on March 31, 2018.

Added

• Most of the constructors now have call alias so you can compose them with Procs nicely if you've switched to Ruby 2.6 (flash-gordon)

  pipe = -> x { x.upcase } >> Success
  pipe.('foo') # => Success('FOO')

• List#collect gathers Some values from the list (flash-gordon)

  include Dry::Monads::List::Mixin
  include Dry::Monads::Maybe::Mixin
  # ...
  List[10, 5, 0].collect do |divisor|
    if divisor.zero?
      None()
    else
      Some(n / divisor)
    end
  end
  # => List[4, 2]

  Without block:

  List[Some(5), None(), Some(3)].collect.map { |x| x * 2 }
  # => [10, 6]

• Right-biased monads got #flatten and #and (falsh-gordon)

  #flatten removes one level of monadic structure, it's useful when you're dealing with things like Maybe of Maybe of something:

  include Dry::Monads::Maybe::Mixin
  
  Some(Some(1)).flatten # => Some(1)
  Some(None()).flatten # => None
  None().flatten # => None

  In contrast to Array#flatten, dry-monads' version removes only 1 level of nesting, that is always acts as Array#flatten(1):

  Some(Some(Some(1))).flatten # => Some(Some(1))

  #and is handy for combining two monadic values and working with them at once:

  include Dry::Monads::Maybe::Mixin
  
  # using block
  Some(5).and(Some(3)) { |x, y| x + y } # => Some(8)
  # without block
  Some(5).and(Some(3)) # => Some([5, 3])
  # other cases
  Some(5).and(None()) # => None()
  None().and(Some(5)) # => None()

• Concise imports with Dry::Monads.[]. You're no longer required to require all desired monads and include them one-by-one, the [] method handles it for you (flash-gordon)

  require 'dry/monads'
  
  class CreateUser
    include Dry::Monads[:result, :do]
  
    def initialize(repo, send_email)
      @repo = repo
      @send_email = send_email
    end
  
    def call(name)
      if @repo.user_exist?(name)
        Failure(:user_exists)
      else
        user = yield @repo.add_user(name)
        yield @send_email.(user)
        Success(user)
      end
    end
  end

• Task.failed is a counterpart of Task.pure, accepts an exception and returns a failed task immediately (flash-gordon)

Compare v1.1.0...v1.2.0