View Source Aja.List (Aja v0.6.5)

Some extra helper functions for working with lists, that are not in the core List module.

Summary

Functions

Prepends an element to a list, equivalent of [elem | list] that can be used in a pipe.

Populates a list of size n by calling generator_fun repeatedly.

Functions

Prepends an element to a list, equivalent of [elem | list] that can be used in a pipe.

Examples

iex> [2, 3, 5, 8] |> Aja.List.prepend(1)
[1, 2, 3, 5, 8]
Link to this function

repeat(generator_fun, n)

View Source

Populates a list of size n by calling generator_fun repeatedly.

Examples

# Although not necessary, let's seed the random algorithm
iex> :rand.seed(:exrop, {1, 2, 3})
iex> Aja.List.repeat(&:rand.uniform/0, 3)
[0.7498295129076106, 0.06161655489244533, 0.7924073127680873]

# It is basically just syntactic sugar for the following:
iex> Stream.repeatedly(&:rand.uniform/0) |> Enum.take(3)

Rationale

  • It offers has a consistent API with Stream.repeatedly/1 and List.duplicate/2

  • It provides a less verbose way of writing one of the most common uses of Stream.repeatedly/1

  • (before Elixir 1.12) It removes the temptation to write the following, which is more concise but is technically incorrect:

    iex> incorrect = fn n -> for _i <- 1..n, do: :rand.uniform() end
    iex> incorrect.(0) |> length()
    2
    iex> Enum.to_list(1..0)  # <- because of this
    [1, 0]

    Elixir 1.12 solved this problem by introducing a step, 1..n//1.

  • It is more efficient