Numa

Lightweight compile-time symbolic constants for Elixir using macros.

Numa lets you define enum-like constants at compile-time using Elixir macros.

Inspired by traditional enums in languages like Java, Rust, or C#, Numa brings that concept to Elixir in a lightweight, idiomatic way. These are not related to Elixir’s Enum module — Numa is designed for defining named constants that expand at compile time, offering both performance and clarity.

Features

• Define enums using plain values or key-value pairs — supports strings, atoms, and integers.
• Macro names are automatically prefixed with _ to ensure valid names, even if keys start with digits.
• Provides helper functions to retrieve all enum keys, values, or key-value pairs.
• Validates input and raises clear errors for invalid enum entries.

Installation

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

def deps do
  [
    {:numa, "~> 0.1.1"}
  ]
end

Then fetch dependencies:

mix deps.get

Usage

Defining simple enums

When names and values are the same:

defmodule Enums do
  use Numa, ["FULL", "1M"]
end

Enums._FULL()  # => "FULL"
Enums._1M()    # => "1M"

Defining enums with explicit names and values

defmodule Enums do
  use Numa, [M3: "3m", MINI: "MINI"]
end

Enums._M3()    # => "3m"
Enums._MINI()  # => "MINI"

Mixed enums and helper functions

defmodule Enums do
  use Numa, ["FULL", "1M", M3: "3m", mini: "MINI"]
end

Enums._FULL()    # => "FULL"
Enums._1M()      # => "1M"
Enums._M3()      # => "3m"
Enums._mini()    # => "MINI"

Enums.values()   # => ["FULL", "1M", "3m", "MINI"]
Enums.keys()     # => [:_FULL, :_1M, :_M3, :_mini]
Enums.all()      # => [{:_FULL, "FULL"}, {:_1M, "1M"}, {:_M3, "3m"}, {:_mini, "MINI"}]

Dynamic enum list

You can also pass a function returning a list:

defmodule Enums do
  use Numa, fn -> ["A", "B", "C"] end
end

Enums._A()   # => "A"

Error handling

Invalid input raises clear errors:

defmodule InvalidEnums do
  use Numa, [%{}]  # Raises ArgumentError: Invalid Numa list value: %{}, expected type: atom, binary or integer
end

Documentation

Full API docs available on HexDocs.

Contributing

Contributions are welcome via issues or pull requests. Created and maintained by Centib.

License

Released under the MIT License.