Deffunctor

Deffunctor provides a way to define module functors similar to functors in OCaml.

Usage

Suppose we have a module that computes something:

defmodule Doubler do
  def f(x), do: x * 2
end

And then we want to wrap this behaviour in some kind of logger. We define a functor that accomplishes just that:

import Deffunctor

deffunctor Logger.(module, printer) do
  def f(x) do
    result = module.f(x)
    printer.(result)
    result
  end
end

Now we can instantiate our Doubler that logs results:

logging_doubler = Logger.new(Doubler, &IO.inspect/1)
logging_doubler.f(2)

And we can see that it prints the value, that's the same as the one returned from the function.

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

def deps do
  [
    {:deffunctor, git: "https://github.com/yunmikun2/deffunctor"}
  ]
end