By definition a Functor is simply a first class method, but these are common in the form of Method and Proc. So for Ruby a Functor is a more specialized as a Higher-order function or Metafunction. Essentally, a Functor can vary its behavior accorrding to the operation applied to it.
f = Functor.new { |op, x| x.send(op, x) } (f + 1) #=> 2 (f + 2) #=> 4 (f + 3) #=> 6 (f * 1) #=> 1 (f * 2) #=> 4 (f * 3) #=> 9
Functors can be somewhat inefficient if a new Functor is frequently recreated for the same use. So this cache can be used to speed things up.
The key will always be an array, wich makes it easier to cache functor for multiple factors.
# File lib/core/facets/functor.rb, line 23 def self.cache(*key, &function) @cache ||= {} if function @cache[key] = new(&function) else @cache[key] end end
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