gistfile1.txt

#!/usr/bin/env ruby -wKU

module Kernel
  
  alias λ proc
  
  def ∑ *terms
    terms.inject { |sum, term| sum + term }
  end
  
  def √ term
    Math.sqrt term
  end
  
end

def say_formula text, a, b, formula
  puts "#{text}#{formula.call(a, b)}"
end

a, b = 2, 3
say_formula "Pythagoras says if a is #{a} and b is #{b} then c is ", a, b, λ {|a,b| √ a*a + b*b }
say_formula "I say if a is #{a} and b is #{b} then a + b = ", a, b, λ {|a,b| ∑ a, b }