Class: Deterministic::Option

Inherits:
Object
  • Object
show all
Includes:
Monad, PatternMatching
Defined in:
lib/deterministic/option.rb

Overview

Abstract parent of Some and None

Direct Known Subclasses

None, Some

Defined Under Namespace

Modules: PatternMatching Classes: None, Some

Class Method Summary collapse

Instance Method Summary collapse

Methods included from PatternMatching

#match

Methods included from Monad

#==, #bind, #fmap, #initialize, #inspect, #join, #to_s, #value

Class Method Details

.any?(expr) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/deterministic/option.rb', line 30

def any?(expr)
  to_option(expr) { expr.nil? || not(expr.respond_to?(:empty?)) || expr.empty? }
end

.some?(expr) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/deterministic/option.rb', line 26

def some?(expr)
  to_option(expr) { expr.nil? }
end

.to_option(expr, &predicate) ⇒ Object 



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# File 'lib/deterministic/option.rb', line 34

def to_option(expr, &predicate)
  predicate.call(expr) ? None.new : Some.new(expr)
end

.try! ⇒ Object 



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# File 'lib/deterministic/option.rb', line 38

def try!
  yield rescue None.new
end

Instance Method Details

#+(other) ⇒ Object

Add the inner values of two Some



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# File 'lib/deterministic/option.rb', line 54

def +(other)
  return other if none?
  fmap { |v| 
    other.match {
      some { v + other.value }
      none { self }
    }
  }
end

#map(proc = nil, &block) ⇒ Object 



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# File 'lib/deterministic/option.rb', line 43

def map(proc=nil, &block)
  return self if none?
  bind(proc || block)
end

#none? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/deterministic/option.rb', line 68

def none?
  is_a? None
end

#some? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/deterministic/option.rb', line 64

def some?
  is_a? Some
end

#value_or(default) ⇒ Object 



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# File 'lib/deterministic/option.rb', line 72

def value_or(default)
  return default if none?
  return value
end

#value_to_a ⇒ Object

Convert the inner value to an Array



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# File 'lib/deterministic/option.rb', line 49

def value_to_a
  map { self.class.new(Array(value)) }
end