Lavash.Rx.Functions (Lavash v0.4.0-rc.1)

Module for defining reusable reactive functions that can be imported into LiveViews.

Usage

Create a module with defrx functions:

defmodule MyApp.Validators do
  use Lavash.Rx.Functions

  defrx valid_email?(email) do
    String.length(email) > 0 && String.contains?(email, "@")
  end

  defrx valid_phone?(phone) do
    String.match?(phone, ~r/^\d{10}$/)
  end
end

Then import them in your LiveView:

defmodule MyAppWeb.UserLive do
  use Lavash.LiveView
  import Lavash.Rx
  import_rx MyApp.Validators

  calculate :email_valid, rx(valid_email?(@email))
  calculate :phone_valid, rx(valid_phone?(@phone))
end

How it works

When you use Lavash.Rx.Functions:

1. The defrx macro becomes available for defining functions
2. At compile time, all defrx definitions are collected
3. A __defrx_definitions__/0 function is generated that returns all definitions
4. Other modules can import these definitions using import_rx

Important constraints

• defrx function bodies must be single expressions
• No intermediate variable assignments (e.g., x = 1 is not allowed)
• All code must be transpilable to JavaScript (see Lavash.Rx.Transpiler)

Example with nested functions

You can call other defrx functions from within a defrx body:

defmodule MyApp.CardValidators do
  use Lavash.Rx.Functions

  defrx expected_length(is_amex) do
    if(is_amex, do: 15, else: 16)
  end

  defrx valid_card_number?(digits, is_amex) do
    String.match?(digits, ~r/^\d+$/) &&
      String.length(digits) == expected_length(is_amex)
  end
end