Piping Up With Elixir

One neat feature of Elixir is the pipe operator (|>). The pipe operator lets you avoid awkward code like this:


Or this:

const firstResult = firstFunction(x);
const secondResult = secondFunction(firstResult);

Instead of having to read in reverse or litter your code with single-use variables, Elixir lets you pipe your function calls together.

|> second_function()
|> third_function()

The pipe operator takes the result of the expression to the left and makes it the first argument to the following function call. Functions from the standard library generally have a consistent argument order, which makes them very easy to compose using the pipe operator.

"Here are some words"
|> String.upcase()   # => "HERE ARE SOME WORDS"
|> String.split(" ") # => ["HERE", "ARE", "SOME", "WORDS"]
|> Enum.reverse()    # => ["WORDS", "SOME", "ARE", "HERE"]
|> Enum.filter(&(String.length(&1) == 4)) # => ["SOME", "HERE"]
|> List.first()      #=> "SOME"

The pipe operator is just one of many things I enjoy about Elixir. It feels very similar to using a fluent interface, but without objects or methods.