Higher Order Functions in Ruby

higher_order_functions.rb

# takes one or more functions as arguments

sum_of_powers = ->(a, b, power_function){
  power_function.(a) + power_function.(b)
}
 
power_of_2 = ->(x){ x * x }
 
puts sum_of_powers.(3 , 2, power_of_2)
 
power_of_3 = ->(x){ x * x * x}
 
puts sum_of_powers.(3 , 2, power_of_3)


# returns function as its results:

generate_sum_of_powers_of_n = ->(exponent){
  ->(a,b){a ** exponent + b ** exponent}
}
 
sum_of_powers_of_2 = generate_sum_of_powers_of_n.(2)
 
sum_of_powers_of_3 = generate_sum_of_powers_of_n.(3)
 
puts sum_of_powers_of_2.(3, 2)  #=> 14
 
puts sum_of_powers_of_3.(3, 2)  #=> 35

# Examples were extracted from: http://leikind.org/lazy/#6