CODEWITHSUNDEEP
functional-programmingelixir
Chedy2149
Chedy2149

Reputation: 3051

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

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.

Upvotes: 3

Views: 289

Answers (3)

ktec
ktec

Reputation: 2473

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.

Upvotes: 1

coderVishal
coderVishal

Reputation: 9079

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]

Upvotes: 8

Gazler
Gazler

Reputation: 84140

You can do this with Enum.slice/2 providing a decreasing range with a negative end:

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

Upvotes: 4

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