OptionEx

OptionEx is a module for handling functions returning a t:OptionEx.t/0. This module is inspired by the f# Option module, and Railway Oriented Programming as explained by Scott Wlaschin. This module is intended to make working with nil values more safe and convenient. For splitting tracks based on ok or error return values see ResultEx.

The Option type consists of either a {:some, term} where the term represents a value, or the :none atom representing the lack of a value.

By replacing optional nil values with an t:OptionEx.t/0, it is no longer needed to match nil value cases. By using OptionEx.map/2 or OptionEx.bind/2 the function passed as second argument will only be executed when a value is present. By using OptionEx.or_else/2 or OptionEx.or_else_with/2 it is possible to add a default value, or behaviour to be executed only in case there is no value.

Examples

    iex> find_by_id = fn
    ...>   1 -> nil
    ...>   x -> %{id: x}
    ...> end
    ...>
    ...> find_by_id.(2)
    ...> |> OptionEx.return()
    {:some, %{id: 2}}

    ...>
    ...> find_by_id.(1)
    ...> |> OptionEx.return()
    :none

    ...>
    ...> find_by_id.(2)
    ...> |> OptionEx.return()
    ...> |> OptionEx.map(fn record -> record.id end)
    ...> |> OptionEx.map(&(&1 + 1))
    ...> |> OptionEx.bind(find_by_id)
    {:some, %{id: 3}}

    ...>
    ...> find_by_id.(1)
    ...> |> OptionEx.return()
    ...> |> OptionEx.map(fn record -> record.id end)
    ...> |> OptionEx.map(&(&1 + 1))
    ...> |> OptionEx.bind(find_by_id)
    :none

    ...>
    ...> find_by_id.(2)
    ...> |> OptionEx.return()
    ...> |> OptionEx.or_else_with(fn -> find_by_id.(0) end)
    %{id: 2}

    ...>
    ...> find_by_id.(1)
    ...> |> OptionEx.return()
    ...> |> OptionEx.or_else_with(fn -> find_by_id.(0) end)
    %{id: 0}

Installation

The package can be installed by adding option_ex to your list of dependencies in mix.exs:

def deps do
  [
    {:option_ex, "~> 0.1.0"}
  ]
end

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• Documentation can be found at https://hexdocs.pm/option_ex.