Trouble porting a Oracle PL/SQL procedure to PL/pgSQL

Hello.  I'm using PostgreSQL to learn SQL and SQL-based languages.  The
text I'm using (SAMS Teach Yourself SQL in 21 Days, 3rd.ed.) references
Oracle in its examples, though I can usually get PostgreSQL to work
almost as well.

Well, I'm almost to the end of the book and I'm trying to port some of
the book's PL/SQL examples to PL/pgSQL, with mixed success.  In this
case, I translated

BEGIN       DECLARE                 UnknownPayType EXCEPTION;                 CURSOR pay_cursor IS
SELECTname, pay_type, pay_rate, eff_date, sysdate,
 
rowid                  FROM pay_table;                 IndRec pay_cursor%ROWTYPE;         . . . 
END;
/

to this:

CREATE OR REPLACE FUNCTION update_pay() RETURNS VOID AS '        DECLARE         pay_cursor CURSOR IS          SELECT
name,pay_type, pay_rate, eff_date, current_date, oid          FROM pay_table;         IndRec pay_cursor%ROWTYPE;
cOldDate DATE;       . . .        END;
 
'
LANGUAGE 'plpgsql';

The problem is, when I call the function, I get:

sql-practice=# select update_pay();
ERROR:  pay_cursor: no such class
WARNING:  plpgsql: ERROR during compile of update_pay near line 2
WARNING:  plpgsql: ERROR during compile of update_pay near line 2
ERROR:  pay_cursor: no such class

I tried several ways of defining pay_cursor, with the same result.
What am I to do?