The Pipe operator¶

The pipe operator is used to setup a chain of method calls that pass results from one to other.

For example, we might have a function that uses 3 of the previously created methods:

def create_hand(hand_size) do
    deck = Cards.create_deck
    deck = Cards.shuffle(deck)
    hand = Cards.deal(deck, hand_size)
end

This code contains repetitive code and can be refactored by using the pipe operator:

def create_hand(hand_size) do
    Cards.create_deck
    |> Cards.shuffle
    |> Cards.deal(hand_size)
end

So the create_deck method is executed and fed into the shuffle method. The result of the shuffle method is fed into the deal method. Notice that the deal method accepts 2 arguments, only one is provided, it feeds the deck argument as well.

Provided this, it requires that you create methods with consistend arguments. If the method had different order of arguments like hand_size and then deal, it wouldn't know that.