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.