Module: Decider

Defined in:
lib/decider.rb,
lib/decider/state.rb,
lib/decider/reactor.rb,
lib/decider/version.rb,
lib/decider/in_memory.rb,
lib/decider/event_sourcing.rb

Defined Under Namespace

Modules: Reactor, View Classes: EventSourcing, InMemory, Left, Module, Pair, Right, State

Constant Summary collapse

StateAlreadyDefined = 
Class.new(StandardError)
StateNotDefined = 
Class.new(StandardError)
VERSION = 
"0.10.0"

Class Method Summary collapse

Class Method Details

.apply(f, x) ⇒ Object 



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# File 'lib/decider.rb', line 367

def self.apply(f, x)
  map2(->(f, x) { f.call(x) }, f, x)
end

.compose(left, right) ⇒ Object 



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# File 'lib/decider.rb', line 229

def self.compose(left, right)
  define do
    initial_state Pair.new(
      left: left.initial_state,
      right: right.initial_state
    )

    decide proc { command in [:left, _] } do
      left.decide(command.value, state.left).each { emit Left.new(_1) }
    end

    decide proc { command in [:right, _] } do
      right.decide(command.value, state.right).each { emit Right.new(_1) }
    end

    evolve proc { event in [:left, _] } do
      state.with(
        left: left.evolve(state.left, event.value)
      )
    end

    evolve proc { event in [:right, _] } do
      state.with(
        right: right.evolve(state.right, event.value)
      )
    end

    terminal? do
      left.terminal?(state.left) && right.terminal?(state.right)
    end
  end
end

.define(&block) ⇒ Object 



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# File 'lib/decider.rb', line 224

def self.define(&block)
  builder = Builder.new
  builder.build(&block)
end

.dimap_on_event(fl, fr, decider) ⇒ Object 



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# File 'lib/decider.rb', line 318

def self.dimap_on_event(fl, fr, decider)
  define do
    initial_state decider.initial_state

    decide proc { true } do
      decider.decide(command, state).each do |event|
        emit fr.call(event)
      end
    end

    evolve proc { true } do
      decider.evolve(state, fl.call(event))
    end

    terminal? do
      decider.terminal?(state)
    end
  end
end

.dimap_on_state(fl, fr, decider) ⇒ Object 



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# File 'lib/decider.rb', line 292

def self.dimap_on_state(fl, fr, decider)
  define do
    initial_state fr.call(decider.initial_state)

    decide proc { true } do
      decider.decide(command, fl.call(state)).each(&method(:emit))
    end

    evolve proc { true } do
      fr.call(decider.evolve(fl.call(state), event))
    end

    terminal? do
      decider.terminal?(fl.call(state))
    end
  end
end

.lmap_on_command(fn, decider) ⇒ Object 



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# File 'lib/decider.rb', line 262

def self.lmap_on_command(fn, decider)
  define do
    initial_state decider.initial_state

    decide proc { true } do
      decider.decide(fn.call(command), state).each(&method(:emit))
    end

    evolve proc { true } do
      decider.evolve(state, event)
    end

    terminal? do
      decider.terminal?(state)
    end
  end
end

.lmap_on_event(fn, decider) ⇒ Object 



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# File 'lib/decider.rb', line 310

def self.lmap_on_event(fn, decider)
  dimap_on_event(fn, ->(event) { event }, decider)
end

.lmap_on_state(fn, decider) ⇒ Object 



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# File 'lib/decider.rb', line 280

def self.lmap_on_state(fn, decider)
  dimap_on_state(fn, ->(state) { state }, decider)
end

.many(decider) ⇒ Object 



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# File 'lib/decider.rb', line 338

def self.many(decider)
  define do
    initial_state({})

    decide proc { [command, state] in [[_id, _], Hash] } do
      command => [id, command]

      ds = state.fetch(id) { decider.initial_state }

      decider.decide(command, ds).each do |event|
        emit [id, event]
      end
    end

    evolve proc { [state, event] in [Hash, [_id, _]] } do
      event => [id, event]

      ds = state.fetch(id) { decider.initial_state }
      ds = decider.evolve(ds, event)

      state.merge(id => ds)
    end

    terminal? do
      state.any? && state.all? { |_, ds| decider.terminal?(ds) }
    end
  end
end

.map(fn, decider) ⇒ Object 



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# File 'lib/decider.rb', line 284

def self.map(fn, decider)
  dimap_on_state(->(state) { state }, fn, decider)
end

.map2(fn, dx, dy) ⇒ Object 



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# File 'lib/decider.rb', line 371

def self.map2(fn, dx, dy)
  define do
    initial_state fn.call(dx.initial_state, dy.initial_state)

    decide proc { true } do
      dx.decide(command, state).each(&method(:emit))
      dy.decide(command, state).each(&method(:emit))
    end

    evolve proc { true } do
      fn.call(
        dx.evolve(state, event),
        dy.evolve(state, event)
      )
    end

    terminal? do
      dx.terminal?(state) && dy.terminal?(state)
    end
  end
end

.rmap_on_event(fn, decider) ⇒ Object 



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# File 'lib/decider.rb', line 314

def self.rmap_on_event(fn, decider)
  dimap_on_event(->(event) { event }, fn, decider)
end

.rmap_on_state(fn, decider) ⇒ Object 



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# File 'lib/decider.rb', line 288

def self.rmap_on_state(fn, decider)
  dimap_on_state(->(state) { state }, fn, decider)
end