Erlang — How to convert a fun() object to a String

Is there a straightforward way to convert an Erlang fun to a string? A call to io_lib:format only prints the function reference, e.g. something like "#Fun". For example, I'd like to be able to do this:

1> Fun = fun() -> atom_to_list('hello world') end.
2> FunStr = fun_to_str(Fun).
"fun() -> atom_to_list('hello world') end."

I'm looking for how to implement fun_to_str. In javascript, some interpreters have a .toSource() function that can be called on any object, including functions, that print their string representation. Any info is appreciated, thanks.