Thinking loops in Elixir

[utterances-bot]

Thinking loops in Elixir

Approaches for converting imperative loops into functional Elixir.

https://alexpearce.me/2023/06/elixir-loops/

[bossek]

Hi, you can still use for approach:

require Integer
all_numbers = [4, 2, 5, 9, 6, 1, 0]
even_numbers = for num <- all_numbers, Integer.is_even(num), do: num
IO.inspect(even_numbers)

[alexpearce]

Heh, quite right @bossek! for is pretty flexible and I struggled to come up with a short example that for couldn't manage.

[RuthraiahThulasi]

there is a reduce option in for loop , which can be treated as 3rd option

acc = []
for x <- 1..40, reduce: acc do
acc -> [ x | acc ]
end

[RuthraiahThulasi]

Updating the above example using 3 approach using loop reduce

all_numbers = [4, 2, 5, 9, 6, 1, 0]
even_numbers = []

for num <- all_numbers, reduce: even_numbers do
even_numbers ->
if Integer.mod(num, 2) == 0 do
even_numbers = [num | even_numbers]
else
even_numbers
end
end

[mxgrn]

Enum.flat_map/2: maps a function and flattens the final list. Useful if an invocation of the mapping function returns multiple elements.

I would add: multiple or zero elements.

[alimnastaev]

You also can loop using Enum.filter/2 (or Enum.reject/2 with reversed logic)

Enum.filter(all_numbers, &rem(&1, 2) == 0)

But underneath, it's all reduce or tail call recursion.