Programming Elixir 1.2

Streams—Lazy Enumerables

In Elixir, the Enum module is greedy. This means that when you pass it a collection, it potentially consumes all the contents of that collection. It also means the result will typically be another collection. Look at the following pipeline:

enum/pipeline.exs

[ 1, 2, 3, 4, 5 ]
|> Enum.map(&(&1*&1))
|> Enum.with_index
|> Enum.map(fn {value, index} -> value - index end)
|> IO.inspect   #=> [1,3,7,13,21]

The first map function takes the original list and creates a new list of its squares. with_index takes this list and returns a list of tuples. The next map then subtracts the index from the value, generating a list that gets passed to IO.inspect.

So, this pipeline generates four lists on its way to outputting the ...