Kofi A. Asare
Sometimes, In a dynamic typed language(interactive), you quickly want to group instructions to acheive a behaviour and
repeated use i.e function.
E.g: A function to find the sum of a list of numbers can be implemented so.
Ruby
#irb
def sum(list_of_numbers)
list_of_numbers.reduce(:+)
end
sum [1,2,3,4,5] #=> 15Javascript
//node repl
function sum(listOfNumbers){
return listOfNumbers.reduce((acc = 0, n) => acc + n)
}
sum([1,2,3,4,5]) //=> 15
Elixir
Such flexibility isn’t quite the case in elixir. Demostrated above, elixir simply doesn’t allow defining and calling named
functions outside of a module.
#iex
def sum(list_of_numbers) do
Enum.reduce(list_of_numbers, fn(a, n) -> a + n end)
end
sum [1,2,3,4,5] #=>
** (ArgumentError) cannot invoke def/2 outside module
(elixir) lib/kernel.ex:5212: Kernel.assert_module_scope/3
(elixir) lib/kernel.ex:3972: Kernel.define/4
(elixir) expanding macro: Kernel.def/2
iex:1: (file)Aaah!
The simple answer is that You can't!.
Why ?
This is because, the hot code swapping feature in elixir relies on having a module as the code container.
Workaround 🙏
However, this can be made possible with an anonymous function
#iex
sum = fn(list) -> Enum.reduce(list, &(&1 + &2)) end
sum.([1,2,3,4,5]) |> IO.puts #=> 15 👍