v1.6.0

Changed

• This version uses dry-core 1.0 (@flash-gordon)

Compare v1.5.0...v1.6.0

v1.5.0

Changed

• Use zeitwerk for auto-loading dry-monads classes (@flash-gordon)
• Task#then is deprecated in favor of Task#bind (@flash-gordon)
• Minimal Ruby version is now 2.7 (@flash-gordon)
• Either (old name of Result) was removed (@flash-gordon)

Compare v1.4.0...v1.5.0

v1.4.0

Added

• Unit destructures to an empty array (flash-gordon)
• When .value! called on a Failure value the error references to the value (rewritten + flash-gordon)

  begin
    Failure("oops").value!
  rescue => error
    error.receiver # => Failure("oops")
  end

• Result#alt_map for mapping failure values (flash-gordon)

  Failure("oops").alt_map(&:upcase) # => Failure("OOPS")

• Try#recover recovers from errors (flash-gordon)

  error = Try { Hash.new.fetch(:missing) }
  error.recover(KeyError) { 'default' } # => Try::Value("default")

• Maybe#filter runs a predicate against the wrapped value. Returns None if the result is false (flash-gordon)

  Some(3).filter(&:odd?)  # => Some(3)
  Some(3).filter(&:even?) # => None
  # no block given
  Some(3 == 5).filter     # => None

• RightBiased#| is an alias for #or (flash-gordon)

  None() | Some(6) | Some(7) # => Some(6)
  Failure() | Success("one") | Success("two") # => Success("one")

Fixed

• Do notation preserves method visibility (anicholson + flash-gordon)

Changed

• Coercing nil values to None with Some#fmap is officially deprecated. (flash-gordon)
  Switch to Some#maybe when you expect nil.
  This behavior will be dropped in 2.0 but you can opt-out of warnings for the time being

  Dry::Monads::Maybe.warn_on_implicit_nil_coercion false

• Minimal Ruby version is 2.6

Compare v1.3.5...v1.4.0

v1.3.5

Added

• Smarter keys deconstruction in pattern matching (flash-gordon)

Compare v1.3.4...v1.3.5

v1.3.4

v1.3.4 2019-12-28

Fixed

• One more delegation warning happenning in do notation (flash-gordon)

Compare v1.3.3...v1.3.4

v1.3.3

v1.3.3 2019-12-11

Fixed

• Incompatibility with Rails. Internal (!) halt exceptions now use mutable backtraces because spring mutates (!) them. For the record, this a bug in Rails (johnmaxwell)

Compare v1.3.2...v1.3.3

v1.3.2

v1.3.2 2019-11-30

Fixed

• Warnings about keywords from Ruby 2.7 (flash-gordon)

Added

• Pattern matching syntax was improved by implementing #deconstruct_keys. Now curly braces aren't necessary when the wrapped value is a Hash (flash-gordon)

  case result
  in Success(code: 200...300) then :ok
  end

Internal

• Performance of do notation was improved for failing cases (1.2x to 1.3x on synthetic benchmarks) (flash-gordon)

Compare v1.3.1...v1.3.2

v1.3.1

v1.3.1 2019-09-07

Fixed

• Added missing None#maybe 😅 (flash-gordon)

Compare v1.3.0...v1.3.1

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

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