function
Get_SSN (E : Employee_Type) return SSN_Type is
begin
return E.SSN;
end;
function
"<" (SSN : SSN_Type;
E : Employee_Type) return Boolean is
begin
return SSN < E.SSN;
end;
function
">" (SSN : SSN_Type;
E : Employee_Type) return Boolean is
begin
return SSN > E.SSN;
end;
package
SSN_Keys is new Employee_Sets.Generic_Keys
(Key_Type => SSN_Type,
Key
=> Get_SSN,
"<" => "<",
">" => ">");