steady_vector

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Hex version CI status Supported Erlang/OTP versions API reference

steady_vector is a persistent vector for Erlang and Elixir: an array-like collection of values optimized for tail growth and shrinkage. It's heavily based on Dmitry Kakurin's PersistentVector implementation for Elixir and, other than some idiomatic changes and a few new functions, its interface is conceptually very similar.

steady_vector optimizes the following operations:

  • getting the element count
  • looking up an element by its 0-based index
  • updating an element by its 0-based index
  • appending a new element to the end
  • removing the last element
  • enumeration
  • mapping
  • folding (left and right)

Getting the element count is O(1); most other operations are O(log32(N)).

It is implemented as a tree with 32-way branching at each level and uses structural sharing for updates. All ideas are borrowed directly from PersistentVector, which in turn borrowed them from Clojure.

Installation

Erlang

Add steady_vector to your list of dependencies in rebar.config:

{deps, [
    {steady_vector, "~> 1.1"}
]}.

And then run rebar3 compile.

Elixir

Add steady_vector to your list of dependencies in mix.exs:

def deps do
    [
        {:steady_vector, "~> 1.1"}
    ]
end

And then run mix deps.get.

Documentation

The API reference is available on HexDocs.

Requirements

steady_vector is tested against Erlang/OTP 24 to 29. The supported build tool is rebar3.

License

steady_vector is licensed under the MIT license. See the LICENSE file for details.