plsql - How to customize return statement in PL/SQL block -

i'm writing stored function called make_email accept input arguments first name , lastname , return varchar2 value containing email address in form of first initial of firstname followed full last name followed @hpu.edu.

ex: calling select make_email('edward','souza') dual return single value: esouza@hpu.edu

here code:

create or replace function make_email(lastname varchar2(10),firstname varchar(10)) return varchar  f_name varchar; l_name varchar;  begin  return  end make_email; / 

could please me how achieve goal? i'm new in pl/sql.

try this

create or replace function make_email(lastname varchar2(10),firstname varchar2(10))  return varchar         email varchar2;   begin   email := substr(lastname ,1,1)|| firstname || '@hpu.edu'; return email;  end;