如何在Erlang中匹配多個原子？

Question

我怎麼以下，例如

A = atom_a, 
case A of 
atom_b or atom_c -> 
     %do something here; 
atom a -> 
     %do something else! 
end. 

Answer 1

嘗試以下操作：

case is_special_atom(A) of 
    true -> 
     %do something here; 
    false -> 
     %do something else! 
end. 

is_special_atom(atom_b) -> true; 
is_special_atom(atom_c) -> true; 
is_special_atom(_) -> false. 

Answer 2

您可以使用衛士：

A = 'atom_a', 
case A of 
    B when B =:= 'atom_b'; B =:= 'atom_c' -> 
    %do something here; 
    'atom_a' -> 
    %do something else! 
end.