in_list function for PostgreSQL

CREATE_FUNCTION_IN_LIST.sql

CREATE OR REPLACE FUNCTION SF_IN_LIST(
    p_list1 text[],
    p_list2 text[]
) RETURNS BOOLEAN AS $$
DECLARE
    w_is_in_list BOOLEAN := true;
BEGIN
    IF p_list1 IS NULL OR p_list2 IS NULL THEN
        RETURN false;
    END IF; 

    IF array_length(p_list1, 1) = 0 OR array_length(p_list2, 1) = 0 THEN
        RETURN false;
    END IF; 

    FOR i IN 1..array_length(p_list1, 1) LOOP
        IF p_list1[i] = ANY(p_list2) THEN
        ELSE
            w_is_in_list := false;
            EXIT;
        END IF; 
    END LOOP;

    RETURN w_is_in_list;
END;
$$ LANGUAGE plpgsql;