Monthly Downloads: 125
Programming language: Elixir
License: BSD 2-clause "Simplified" License
Tags: Macros    
Latest version: v0.2.1

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Fast. Really fast.

What is Pathex?

Pathex is a library for performing fast actions with nested data structures in Elixir. With pathex you can trivially set, get and update values in structures. You can checkout benchmarks at https://github.com/hissssst/pathex_bench

Why another library?

Existing methods of accesssing data in nested structures are either slow or do not provide much functionality as put_in or get_in. For example setting the value in structure with Pathex is 5-10x faster than Focus or 2x faster than put_in


def deps do
    {:pathex, "~> 0.1.0"}


  1. You need to import and require Pathex since it's manly operates macros

    require Pathex
    import Pathex, only: [path: 1, "~>": 2]
  2. You need to create the path which defines the path to the item in elixir structure you want to get:

    path_to_strees = path :user / :private / :addresses / 0 / :street

    This creates closure with fn which can get, set and update values in this path

  3. Use the path!

    {:ok, "6th avenue"} = Pathex.view(path_to_streets, %{
    user: %{
    id: 1,
    name: "hissssst",
    private: %{
      phone: "123-456-789",
      adressess: [
         [city: "City", street: "6th avenue", mail_index: 123456]


  1. Paths are really a set of pattern-matching cases. This is done to extract maximum efficency from BEAM elixir # getter for path 1 / "y" # almost equals to case do %{1 => x} -> case x do %{"y" => res} -> {:ok, res} _ -> :error end [_, x | _] -> case x do %{"y" => res} -> {:ok, res} _ -> :error end t when is_tuple(t) and tuple_size(t) > 1 -> case x do %{"y" => res} -> {:ok, res} _ -> :error end end
  2. Paths for special specifications can be created with sigils elixir iex> mypath = ~P[user/name/firstname]json iex> Pathex.over(mypath, %{"user" => %{"name" => %{"firstname" => "hissssst"}}}, &String.capitalize/1) {:ok, %{"user" => %{"name" => %{"firstname" => "Hissssst"}}}} elixir iex> mypath = ~P[:hey/"hey"]naive iex> Pathex.set(mypath, [hey: %{"hey" => 1}], 2) {:ok, [hey: %{"hey" => 2}]}
  3. You can use variables inside paths elixir iex> index = 1 iex> mypath = path :name / index iex> Pathex.view path, %{name: %{0 => "Linus", 1 => "Torvalds"}} {:ok, "Torvalds"} iex> index = 0 iex> Pathex.view path, %{name: %{0 => "Linus", 1 => "Torvalds"}} {:ok, "Torvalds"}
  4. You can create composition of lenses elixir iex> path1 = path :user iex> path2 = path :phones / 1 iex> composed_path = path1 ~> path2 iex> Pathex.view composed_path, %{user: %{phones: ["123-456-789", "987-654-321", "000-111-222"]}} {:ok, "987-654-321"}
  5. Paths can be applied to different types of structures elixir iex> user_path = path :user iex> Pathex.view user_path, %{user: "hissssst"} {:ok, "hissssst"} iex> Pathex.view user_path, [user: "hissssst"] {:ok, "hissssst"}

No Magic

Pathex paths are just closures created with fn. Any path or ~P is a macro for creating a closure. Pathex.view/2 Pathex.set/3 and Pathex.over/3 are just macros for calling these closures. Pathex.~>/2 is a simple macro which creates composition of two closures