Poison

Poison is a new JSON library for Elixir focusing on wicked-fast speed without sacrificing simplicity, completeness, or correctness.

Poison takes several approaches to be the fastest JSON library for Elixir.

Poison uses extensive sub binary matching, a hand-rolled parser using several techniques that are known to benefit HiPE for native compilation, IO list encoding and single-pass decoding.

Preliminary benchmarking has sometimes put Poison’s performance closer to jiffy, and almost always faster than existing Elixir libraries.

defmodule Person do
  defstruct [:name, :age]
end

Poison.decode!(~s({"name": "Devin Torres", "age": 27}), as: Person)
#=> %Person{name: "Devin Torres", age: 27}

Poison.decode!(~s({"people": [{"name": "Devin Torres", "age": 27}]}),
  as: %{"people" => [Person]})
#=> %{"people" => [%Person{age: 27, name: "Devin Torres"}]}

Every component of Poison – the encoder, decoder, and parser – are all usable on their own without buying into other functionality. For example, if you were interested purely in the speed of parsing JSON without a decoding step, you could simply call Poison.Parser.parse.

Parser

iex> Poison.Parser.parse!(~s({"name": "Devin Torres", "age": 27}))
%{"name" => "Devin Torres", "age" => 27}
iex> Poison.Parser.parse!(~s({"name": "Devin Torres", "age": 27}), keys: :atoms!)
%{name: "Devin Torres", age: 27}

Encoder

iex> IO.puts Poison.Encoder.encode([1, 2, 3], [])
"[1,2,3]"

Anything implementing the Encoder protocol is expected to return an IO list to be embedded within any other Encoder’s implementation and passable to any IO subsystem without conversion.

defimpl Poison.Encoder, for: Person do
  def encode(%{name: name, age: age}, _options) do
    Poison.Encoder.BitString.encode("#{name} (#{age})")
  end
end

Benchmarking

$ mix archive.install https://github.com/alco/benchfella/releases/download/v0.1.0/benchfella-0.1.0.ez
$ mix deps.get
$ MIX_ENV=bench mix compile
$ MIX_ENV=bench mix compile.protocols
$ elixir -pa _build/bench/consolidated -pa _build/bench/lib/\*/ebin -S mix bench

License

Poison is released into the public domain (see UNLICENSE). Poison is also optionally available under the ISC License (see LICENSE), meant especially for jurisdictions that do not recognize public domain works.