Ruby Hashes as functions of keys to values

functional_hash.rb

# In Clojure, hash-maps are truly functions of keys to values.
# So you can do `(:a {:a 1})` and get `1` as the result
# Why not put this in Ruby?

# access keys of a hash like a function

class Object
  def respond_to?(method)
    if (method.to_s =~ /^_.*/) == 0
      true
    else
      super
    end
  end
  def method_missing(name, *args, &b)
    if (args.count==1) && b.nil? && name[0]=="_" &&
       args[0].has_key?(name[1..-1].to_sym)
      args[0][name[1..-1].to_sym]
    else
      super
    end
  end
end


hash = {:a => 1}
(_a hash) == 1 #=> true
(_a hash) == (hash [:a]) #=> true

# the underscore serves to prevent naming conflicts to a degree