Question

In ERLANG: Assume we have a function f() that takes F1 as inputs where F1 is a function. Is there a way to know the number of input parameters of F1.

I feel somehow there IS a solution, but I am not sure. for instance:

 -module(high).
 -compile(export_all).

 f1() -> 1.
 f2(X) -> X. 
 f3(X, Y) -> {X,Y}. 

 run(F) -> io:format("F ~p ~n", [F]).

So, is there any way for function run/1 to know information about the passed function [mainly the number of input parameters of the passed function].

Note: Please be informed that this is a theoretical question.
Note: is the code of apply(fun,[arguments]) available in open-source .. this may hep me I guess.

Answer 1

erlang:fun_info(Fun,arity).

For example

F = fun(A,B) -> A+B end.
#Fun<erl_eval.12.111823515>
3> erlang:fun_info(F,arity).
{arity,2}