help -- cursor inside a function

hello ,
i have a procedure as below.

-------------------------------------------------------------------------------------------------------------

create function retrec(integer) returns integer
as
 'declare
        uid alias for $1;
  begin
        declare retrec_cur cursor for select * from jd_user_master where

um_user_id>uid;
        if found then
                fetch 1 from retrec_cur;
                move next from retrec_cur;
                return 1;
        end if;
  end;'
language 'plpgsql';

-------------------------------------------------------------------------------------------------------------------------

this gets created , but while running it i get the error below,
-------------------------------------------------------------------------------------------------------------------

NOTICE:  plpgsql: ERROR during compile of retrec near line 5
ERROR:  parse error at or near "cursor"

--------------------------------------------------------------------------------------------------------------------------

why this is so ? can anyone help me out ? thanx in advance.