simple dictionary without using arrays or hashes

dict.rb

def add(key, value, dictionary = Proc.new{})
  lambda do |x|
    key == x ? value : dictionary.call(x)
  end
end

d = add("a",5)
d = add("b",6, d)

p d.call("b")
p d.call("a")
p d.call("c")

Proc.new is less picky about arity than lambda