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:

 [ 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 ...

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