Pattern Matching With Functions

Hey, dev!

Imagine a scenario where you need to compare 2 numbers and return which one is the biggest.

In Elixir, we can do it by using an ternary if statement:

defmodule CompareNumbers do
  def the_bigger_number_is(number_01, number_02) do
    bigger_number = if number_01 > number_02, do: number_01, else: number_02

    "The number #{number_01} is greater than #{number_02}"
  end
end

number_01 = 10
number_02 = 5

IO.inspect(CompareNumbers.the_bigger_number_is(number_01, number_02))

=> "The number 10 is greater than 5"

...

We can also use Pattern Matching With Functions to control the flow:

defmodule CompareNumbers do
  def the_bigger_number_is(number_01, number_02) do
    compare(number_01 > number_02, number_01, number_02)
  end

  defp compare(true, number_01, number_02) do
    "The number #{number_01} is greater than #{number_02}"
  end

  defp compare(false, number_01, number_02) do
    "The number #{number_02} is greater than #{number_01}"
  end
end

number_01 = 10
number_02 = 5

IO.inspect(CompareNumbers.the_bigger_number_is(number_01, number_02))

=> "The number 10 is greater than 5"

Here, we create 2 private functions with the same name compare, and then, with pattern matching, we check if the first argument is true or false.

So, which of the 2 approaches above do you think is the best? Which makes the most sense?

Or, how could be better? Let me know in the comments below =D

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Comments

[Yasir Asarudheen]

Nice post, I would prefer guard condition

defmodule CompareNumbers do
  def the_bigger_number_is(number_01, number_02) when number_01 > number_02 do
    "The number #{number_01} is greater than #{number_02}"
  end

  defp compare(number_01, number_02) do
    "The number #{number_02} is greater than #{number_01}"
  end
end

number_01 = 10
number_02 = 5

IO.inspect(CompareNumbers.the_bigger_number_is(number_01, number_02))

=> "The number 10 is greater than 5"

[Diego Novais]

Great! And well remembered! The guard condition approach made the code cleaner. Thank you!