Functional Thinking 2.1

sum_list = [5,'four','two',10,'one',28,6,'five']

defmodule SumModule do

@numDic %{ 1 => 'one', 2 => 'two', 3 => 'three', 4 => 'four', 5 => 'five' }

def sum_list([]), do: 0

def sum_list([head|tail]) when is_integer(head), do: sum_list(tail) + head

def sum_list([head|tail]), do: sum_list(tail) + sum_list(Enum.map(@numDic, fn {key, value} -> SumModule.convert_to_integer(head,{key,value}) end))

def convert_to_integer(head, {key, value}) when value === head, do: key

def convert_to_integer(head, {key, value}) when value !== head, do: 0

end

IO.puts SumModule.sum_list(sum_list)