Is there an equivalent to Haskell's init function in elixir?

Question

In Haskell the init function returns all the elements in a list except the last element.
For example init [1, 2, 3] would return [1, 2] .

Is there a similar function in Elixir?

I can't find any similar function in the Enum or List module.

Answer 1

If you like you can also use Enum.drop/2 , which Drops the first count items from the collection. If a negative value count is given, the last count values will be dropped.

[1,2,3] |> Enum.drop(-1) # [1,2]

Answer 2

您可以使用Enum.slice / 2执行此操作，提供具有负端的递减范围 ：

[1, 2, 3] |> Enum.slice(0..-2) # [1, 2]

Answer 3

It's always nice to confirm suspicions in these situations, so here's a benchmark comparing the two:

Settings:
  duration:      1.0 s

## ListBench
[13:29:22] 1/2: Enum.drop(-1)
[13:29:26] 2/2: Enum.slice(0..-2)

Finished in 7.41 seconds

## ListBench
benchmark name     iterations   average time
Enum.drop(-1)           50000   72.32 µs/op
Enum.slice(0..-2)       10000   273.16 µs/op

So yes, Enum.drop is the preferred option.