Class: TAlgebra::Monad::Either

Inherits:
Object
  • Object
show all
Includes:
SingleValued
Defined in:
lib/t_algebra/monad/either.rb

Direct Known Subclasses

Parser

Constant Summary collapse

LEFT = 
:left
RIGHT = 
:right

Class Method Summary collapse

Instance Method Summary collapse

Methods included from SingleValued

included

Class Method Details

.left(err) ⇒ Object 



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# File 'lib/t_algebra/monad/either.rb', line 15

def left(err)
  new(is: LEFT, value: err)
end

.pure(value) ⇒ Object Also known as: right 



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# File 'lib/t_algebra/monad/either.rb', line 10

def pure(value)
  new(is: RIGHT, value: value)
end

Instance Method Details

#==(other) ⇒ Object 



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# File 'lib/t_algebra/monad/either.rb', line 52

def ==(other)
  to_obj == other.to_obj
end

#bind {|value| ... } ⇒ Object

Yields:

  • (value)

Raises:



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# File 'lib/t_algebra/monad/either.rb', line 27

def bind
  raise UseError.new("#bind requires a block") unless block_given?
  return dup if left?

  yield value
end

#fmap ⇒ Object

Raises:



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# File 'lib/t_algebra/monad/either.rb', line 20

def fmap
  raise UseError.new("#fmap requires a block") unless block_given?
  return dup if left?

  self.class.pure(yield(value))
end

#from_either ⇒ Object

Raises:



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# File 'lib/t_algebra/monad/either.rb', line 46

def from_either
  raise UseError.new("#from_either called without block") unless block_given?
  return yield(value) if left?
  value
end

#from_either! ⇒ Object 



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# File 'lib/t_algebra/monad/either.rb', line 42

def from_either!
  from_either { |e| raise UnsafeError.new("#from_either! exception. #{e}") }
end

#left? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/t_algebra/monad/either.rb', line 34

def left?
  is == LEFT
end

#right? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/t_algebra/monad/either.rb', line 38

def right?
  is == RIGHT
end

#to_obj ⇒ Object 



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# File 'lib/t_algebra/monad/either.rb', line 56

def to_obj
  {is.to_s => value, :class => self.class.name}
end