CODEWITHSUNDEEP
elixirpointfree
Prashanth Chandra
Prashanth Chandra

Reputation: 2692

Is there a prefix/Polish notation for the equality operator in Elixir?

I'm learning Elixir, and one of the exercises I've decided to give myself is to try and write the Luhn algorithm for credit card validation in idiomatic Elixir.

I realize that == in Elixir is a Kernel function, which are apparently inlined by the compiler. Is there some kind of utility function that will let me do something like this? 

...
|> == 0

instead of having to define a function to pipe into, as I've done here.

Elixir

defmodule Luhn do
  def equalzero?(x) x == 0 end
  def validate(num) do
    digits = Integer.digits(num)
    len = length digits

    digits
    |> Stream.with_index
    |> Enum.reverse
    |> Enum.reduce(0, fn {digit, index}, acc ->
      if rem(len - index, 2) == 0 do
        acc + digit * 2 |> Integer.digits |> Enum.sum
      else
        acc + digit
      end
    end)
    |> rem(10)
    |> Luhn.equalzero?
  end
end

Upvotes: 1

Views: 226

Answers (1)

Dogbert
Dogbert

Reputation: 222128

You can pipe into such operators (which are defined in Kernel) by referring to their full path, Kernel.==:

iex(1)> 0 |> Kernel.==(0)
true
iex(2)> 1 |> Kernel.==(0)
false

Upvotes: 4

Related Questions