Module: RParsec::Monad

Included in:
Parser
Defined in:
lib/rparsec/monad.rb

Overview

module for Monad

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#this ⇒ Object (readonly)

Returns the value of attribute this.



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# File 'lib/rparsec/monad.rb', line 9

def this
  @this
end

Instance Method Details

#bind(&binder) ⇒ Object

Run the bind operation on the encapsulated object following the monad law.



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# File 'lib/rparsec/monad.rb', line 30

def bind(&binder)
  @monad.bind(@this, &binder)
end

#initMonad(m, v) ⇒ Object

To initialize with a monad implementation and an object that obeys the monad law.

Raises:

  • (ArgumentError) 


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# File 'lib/rparsec/monad.rb', line 14

def initMonad(m, v)
  raise ArgumentError, 'monad cannot be nil' if m.nil?
  @monad = m;
  @this = v;
end

#map(&mapper) ⇒ Object

Run the map operation on the encapsulated object following the monad law. #bind is used to implement.



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# File 'lib/rparsec/monad.rb', line 51

def map(&mapper)
  bind do |v|
    result = mapper.call v;
    value(result);
  end
end

#plus(other) ⇒ Object

Run the plus operation on the encapsulated object following the MonadPlus law.



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# File 'lib/rparsec/monad.rb', line 61

def plus other
  @monad.mplus(@this, other.this)
end

#seq(other) ⇒ Object

Run the seq operation on the encapsulated object following the monad law. If seq is not defined by the monad impl, use #bind to implement.



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# File 'lib/rparsec/monad.rb', line 39

def seq(other)
  if @monad.respond_to? :seq
    @monad.seq(other)
  else
    bind { |_x| other }
  end
end

#value(v) ⇒ Object

To create a value based on the monad impl.



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# File 'lib/rparsec/monad.rb', line 23

def value v
  @monad.value v
end