Mark Chavez

Mark Chavez

Learning how to learn.

Avoid Conditionals in Elixir

August 04, 2017

I used to love conditionals. I think everybody did. It gave us the ability to decide what the system should do depending on many factors. It was a silver bullet.

Not until I was forced to write a collection of complex conditional logics and I didn’t have my refactoring bag with me. It was hell and took me a lot of time to understand and test the code.

Elixir has introduced a fairly new concept to my head called Pattern Matching. It is somewhat similar to regular expressions but is different in many ways. We can use the power of pattern matching to avoid conditionals and thus write a clear and understandable code without the if and else statements.

Consider this example.

defmodule HelloCountry do
  def for(country) do
    if country == "america" do
    else if country  == "japan" do
    else if country == "china" do
      "Nǐ hǎo"

The above example looks typical. Coming from the ruby language, I can safely say that this is a usual solution but not a good one though. Personally, having a conditional logic in a function brings a bunch of complexities.


Because it makes me think. I don’t want to waste my precious time thinking (I’m sure you do too) whether the expression returns true or false.

The Elixir way of doing things

With Elixir, we can use pattern matching directly on functions to make sure that we only call this function if the pattern matched. It basically looks like a group of overloaded methods (if you came from a Java background) but their patterns are different respectively.

You should be alarmed when you see a conditional logic in your Elixir code.

defmodule HelloCountry do
  def for(_country = "america"), do: "Hello"
  def for(_country = "japan"), do: "Kon'nichiwa"
  def for(_country = "china"), do: "Nǐ hǎo"

HelloCountry.for("america") # Hello
HelloCountry.for("japan")   # Kon'nichiwa
HelloCountry.for("china")   # Nǐ hǎo

Pattern matching is one of the core features that made me love this language and it only goes better from here.

Happy reading!

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