Class: Lalka::Task

Inherits:
Object
  • Object
show all
Defined in:
lib/lalka.rb

Overview

TODO: Invalidate resolve and reject at the same time

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(&block) ⇒ Task

Returns a new instance of Task.



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# File 'lib/lalka.rb', line 38

def initialize(&block)
  @computation = block
end

Class Method Details

.id(internal) ⇒ Object 



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# File 'lib/lalka.rb', line 30

def id(internal)
  internal.on_success { |v| v }
  internal.on_error { |e| e }
end

.reject(error) ⇒ Object 



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# File 'lib/lalka.rb', line 18

def reject(error)
  new do |t|
    t.reject(error)
  end
end

.resolve(value) ⇒ Object Also known as: of 



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# File 'lib/lalka.rb', line 12

def resolve(value)
  new do |t|
    t.resolve(value)
  end
end

.try(&block) ⇒ Object 



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# File 'lib/lalka.rb', line 24

def try(&block)
  new do |t|
    t.try(&block)
  end
end

Instance Method Details

#ap(other_task) ⇒ Object 



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# File 'lib/lalka.rb', line 105

def ap(other_task)
  Task.new do |t|
    atom = Concurrent::Atom.new(M.Right(fn: M.None(), arg: M.None()))

    atom.add_observer do |_, _, either|
      if either.right?
        value = either.value

        value[:fn].bind { |fn| value[:arg].fmap(fn) }.fmap do |result|
          t.resolve(result)
          atom.delete_observers
        end
      else
        error = either.value

        t.reject(error)
        atom.delete_observers
      end
    end

    fork do |this|
      this.on_success do |fn|
        atom.swap(fn) { |either, fn| either.bind { |struct| M.Right(struct.merge(fn: M.Some(fn))) } }
      end

      this.on_error do |error|
        atom.swap(error) { |either, error| either.bind { M.Left(error) } }
      end
    end

    other_task.fork do |other|
      other.on_success do |arg|
        atom.swap(arg) { |either, arg| either.bind { |struct| M.Right(struct.merge(arg: M.Some(arg))) } }
      end

      other.on_error do |error|
        atom.swap(error) { |either, error| either.bind { M.Left(error) } }
      end
    end
  end
end

#bind(*args, &block) ⇒ Object Also known as: chain, flat_map 



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# File 'lib/lalka.rb', line 79

def bind(*args, &block)
  block = function_from_arguments(*args, &block)

  Task.new do |t|
    fork do |this|
      this.on_success do |first_value|
        other_task = block.call(first_value)

        other_task.fork do |other|
          other.on_success do |second_value|
            t.resolve(second_value)
          end

          other.on_error do |error|
            t.reject(error)
          end
        end
      end

      this.on_error do |error|
        t.reject(error)
      end
    end
  end
end

#fork {|internal| ... } ⇒ Object

Yields:

  • (internal) 


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# File 'lib/lalka.rb', line 56

def fork
  internal = InternalAsync.new
  yield internal
  internal.call(&@computation)
  nil
end

#fork_wait ⇒ Object 



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# File 'lib/lalka.rb', line 42

def fork_wait
  queue = Queue.new
  internal = Internal.new(queue)

  if block_given?
    yield internal
  else
    Task.id(internal)
  end

  internal.call(&@computation)
  queue.pop
end

#map(*args, &block) ⇒ Object Also known as: fmap 



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# File 'lib/lalka.rb', line 63

def map(*args, &block)
  block = function_from_arguments(*args, &block)

  Task.new do |t|
    fork do |this|
      this.on_success do |value|
        t.resolve(block.call(value))
      end

      this.on_error do |error|
        t.reject(error)
      end
    end
  end
end