obsolete messages

[Wes James]

I have some code that I got from an example:

a2l(A) when atom(A) -> atom_to_list(A);
a2l(L) when list(L) -> L.

l2a(L) when list(L) -> list_to_atom(L);
l2a(A) when atom(A) -> A.

when compiled it says atom/1 and list/1 are obsolete. What are the
replacements for atom/1 and list/1 in the context above?

thx,

-wes