Convert Oracle function to PostgreSQL

Hi,
I use this Oracle function(from  AskTom  -
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:210612357425) 



SQL> create or replace type myTableType as table
     of varchar2 (255);
  2  /

Type created.

ops$tkyte@dev8i> create or replace
     function in_list( p_string in varchar2 ) return myTableType
  2  as
  3      l_string        long default p_string || ',';
  4      l_data          myTableType := myTableType();
  5      n               number;
  6  begin
  7    loop
  8        exit when l_string is null;
  9        n := instr( l_string, ',' );
10         l_data.extend;
11         l_data(l_data.count) :=
                 ltrim( rtrim( substr( l_string, 1, n-1 ) ) );
12         l_string := substr( l_string, n+1 );
13    end loop;
14
15    return l_data;
16  end;
17  /

Function created.

ops$tkyte@dev8i> select *
  2    from THE
        ( select cast( in_list('abc, xyz, 012') as
                              mytableType ) from dual ) a
  3  /

COLUMN_VALUE
------------------------
abc
xyz
012

How can I convert this function into PostgreSQL ? Any thoughts?
Thanks