PostgreSQL - Substring campo TEXT[]

create or replace function subs()

RETURNS VOID AS $$

DECLARE

hs record;

resultado text[];

hs_2 text[];

BEGIN

	for hs in select product_hs from _2018_cabezal_exp limit 100

	loop

		hs_2 := hs.product_hs;

		raise notice '%', hs_2;

	end loop;

end;

$$ language plpgsql;

SELECT array( SELECT substring(unnest('{8414,8532,8533,8536}'::text[]),1,2) )