I have a Plug with many functions that return a parameterized anonymous function, for example:

def scaling(vmin,vmax) do
  fn value ->
    cond do
      not is_number(value)   -> 0
      value <= vmin ->  vmin
      value > vmax ->  vmax
      true -> value
    end
  end
end

The code of the Plug

defmodule Plug.RouterDataProcessor do

  def init(opts), do: opts  
    def call(conn, opts) do
    case conn.private[:process] do
      nil -> conn
      tasks -> process(conn,tasks, opts[:on_error])
    end
  end

  def process(conn,tasks,on_error) do
    Enum.map(tasks,do_task(Map.get(conn.body_params,"items")  ))    
  end

  def do_task(data) do
    fn task ->
      Enum.map(data,fn value ->fd.(value) end)
    end
  end


def scaling(vmin,vmax) do
  fn value ->
    cond do
      not is_number(value)   -> 0
      value <= vmin ->  vmin
      value > vmax ->  vmax
      true -> value
    end
  end
end
end

end

The function is already declared inside the plug.

The function will be passed from the route to the plug,

So in the Route:

defmodule UsersRouter do
  use RouterHelpers
  use Plug.ErrorHandler

import Plug.RouterDataProcessor

plug :match
plug Plug.RouterDataProcessor, on_error: &UsersRouter.on_error_fn/2
plug :dispatch
import Plug.RouterDataProcessor


tasks=[scaling(0,100),group(1),sum(1),sort(2)] # Many function can be grouped in a list

post "/receive/", private: %{process: tasks} do
        # do something with data
	# then send response
	send_json(conn,  %{status: "success"})
end

end

But when compile get the error:
== Compilation error in file lib/routes/data_router.ex ==
** (ArgumentError) cannot escape #Function<1.72916727/1 in DataProcessor.scaling/2>. The supported values are: lists, tuples, maps, atoms, numbers, bitstrings

Then try to capture, but is a incorrect point because I need to capture the returned anonymous function.

My second attemp is use quote/unquote

def scaling(vmin,vmax) do
  quote do
     fn value ->
    cond do
      not is_number(value)   -> 0
      value <= unquote(vmin) -> unquote(vmin)
      value >  unquote(vmax) ->  unquote(vmax)
      true -> value
    end
  end
  end
end

But I can’t find how to execute the quoted expression

 def do_task(data) do
    fn task ->
      IO.inspect task # print the representation {:fn, [], ....
      # try to execute
      Enum.map(data,fn value ->task.(value) end)       
    end
  end

Give me:

** (Plug.Conn.WrapperError) ** (BadFunctionError) expected a function, got:{:fn, [], …

I does not know why have this problem because if I run all inside the “post”,
the code run ok.

post "/datapro/" do 
    send_json(conn,  %{ t:  process(conn,[scaling(5,25)],&UsersRouter.on_error_fn/2)})
end

I am newbie, so is good to resolve with the quoted aproach, or there is any better way ?
Is there any performance drawback when use AST representation ?

How can resolve it ?