Need a simple explanation of the inject method

Question

[1, 2, 3, 4].inject(0) { |result, element| result + element } # => 10

I\'m looking at this code but my brain is not registering how the number 1

Answer 1

[1, 2, 3, 4].inject(0) { |result, element| result + element } # => 10

is equivalent to the following:

def my_function(r, e)
  r+e
end

a = [1, 2, 3, 4]
result = 0

a.each do |value|
  result = my_function(result, value)
end