Pl/PgSql: Loop over Array

Ist it possible to loop over an array:

CREATE FUNCTION atest(INT[]) RETURNS TEXT AS '
DECLARE
myA ALIAS FOR $1;
myI INT;
myRet TEXT='''';
BEGIN
FOR myI IN myA LOOP
myRet=myRet||''x''||myI;
END LOOP;
RETURN myRet;
END;
' LANGUAGE 'plpgsql';

This Examle is not working ;-(

Thanks,
AXEL.