How to forEach in Elixir

Question

How do you forEach in Elixir? In JavaScript (and most languages have an equivalent), I can iterate through the various items in a list and do something with side effects like outputting to the console.

[1,2,3].forEach(function(num) {
    console.log(num);
});

//=> 1
//=> 2
//=> 3

Is there an equivalent in elixir?

Answer 1

Iterating through a collection is most often handled with the Enum module. Enum.each/2 is what you're looking for if you want to generate side effects.

Enum.each/2 function takes two arguments: your collection and a function to run on every member of the collection.

Like so:

iex(3)> Enum.each([1, 2, 3], fn x -> IO.puts x end)
1
2
3
:ok

I wrote a blog post about this recently which goes into more details. The post is a comparison between Elixir and Ruby, but the same exact logic applies to JavaScript.

Answer 2

One option would be to use comprehensions:

for item <- items do
  IO.inspect(item)
end

Another option is to enumerate:

Enum.each items, fn(item) ->
  IO.inspect(item)
end

Answer 3

Another option would be to useEnum.map/2 . Enum.each/2 always returns :ok , while map/2 iterates over the list and returns new values (equivalent to Javascript's Array.map )

iex(3)> Enum.map([1, 2, 3], fn x -> x * x end)
[1, 4, 9]

Answer 4

If you want to use foreach specifically, you could use Erlang's foreach/2 :

 :lists.foreach(fn a -> IO.puts a + a end, [1,2,3])
 # 2
 # 4
 # 6